NSX Timing Belt / Water Pump DIY - NSX Prime Timing Belt / Water Pump DIY By Gary ... crank bolt is fairly easy if you buy the Honda ... exposing two more bolts which hold the fuel

Copyright 2004, NSX Prime, All Rights Reserved

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NSX Timing Belt / Water Pump DIY By Gary Kentosh

Acknowledgements: I would like to thank Larry Bastanza for sending me his timing belt DIY write-up. The service manual is necessary but lacks detail, and being able to visualize this project through the experience of someone else is invaluable. I have made references to Larry's write up, indicated by [LB], and it is not my intention to take credit for insight and experience which is not mine. I strongly suggest getting a copy of Larry's write-up because there is much useful information in it which I have not included here. I would also like to thank NSXPrime for helping me to better understand my NSX during the past 4 years of ownership. Disclaimer: The author and those who distribute this information assume no responsibility for its use or accuracy. Anyone who uses this information for any purpose does so at their own risk. Regarding the pictures that are included, I sorted through hundreds of pictures and chose ones which I thought were unique and pertinent to this particular job. I had many pictures leading up to removal of the head covers, but these are all steps that would be done in a valve adjust DIY, which has been done before. Therefore I did not include any pictures of these steps. I also had to limit the quality and number of pictures included in order to keep the file size reasonable. I found that using a digital camera during the project was extremely useful, as it allowed me to go back and see how things were assembled before I took them apart. Regarding torque settings, I decided not to put torque values into this procedure. These should be taken from the service manual for your model year car. I used the 91 service manual, and I was unsure if any of the torque values had changed for later model cars.

Parts List

Essentials: 14400-PR7-A01 (1) Timing Belt 19200-PR7-A03 (1) Water Pump 31110-PR7-A01 (1) Alternator Belt 38920-PR7-A01 (1) A/C Belt 91318-PY3-000 (1) Oil pedestal gasket "8" 90401-634-000 (1) Timing belt adjuster bolt grommet If you are upgrading to the new style lower timing cover: 11810-PR7-A02 (1) Lower timing belt cover 11816-PR7-000 (1) Grommet for weep tube To renew your head cover gaskets: 12341-PR7-A01 (2) Head cover gasket 12343-PR7-A00 (6) Spark plug gasket 90442-PR7-A00 (12) Head cover washer

“ I L e a r n e d I t O n N S X P r i m e ! ”


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To renew the gaskets associated with the timing covers (optional), about $200 total: 12351-PR7-A00 (1) Front head cover gasket 12352-PR7-A00 (1) Rear head cover gasket 11841-PR7-A00 (1) Lower timing cover gasket ($100) 11842-PR7-A00 (1) Front timing cover gasket A 11843-PR7-A00 (1) Front timing cover gasket B 11844-PR7-A00 (1) Rear timing cover gasket A 11845-PR7-A00 (1) Rear timing cover gasket B If you decide to buy new water pump bolts: 90049-PH7-000 (2) Water pump bolt (12mm) 90052-PH7-000 (7) Water pump bolt (10mm) The Honda crank pulley tool: 07JAB-001020A Crank pulley universal handle 07NAB-001030A Crank pulley wrench tool Honda valve adjust tools: 07MAA-PR70110 Tappet adjuster 07MAA-PR70120 Tappet locknut wrench Honda service mat: 07MAZ-SL0000A Service mat Some other tools: (4) 5mm pin punches (use 3/16" if that's all you can find) Coolant system pressure tester (I got mine at www.eastwood.com) Large black plastic paper clip Permanent marker (dark and light) 17mm crowsfoot for torquing valve adjust nuts Torque wrenches (small, medium, and large) A good set of 6 point metric sockets in 1/4", 3/8", and 1/2" drive BIG drain pan for the coolant



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Here are the 5mm pin punches I used, which just happened to fit perfectly.

Here are the Honda tools, the crank pulley and valve adjust tools. Here are the sections in the 91 service manual which will be of interest: Timing belt: 6-21 to 6-26 Valve adjust: 6-54 to 6-56 Water pump: 10-10, 10-11 Coolant replace: 10-5 to 10-7 Various torque settings, belt adjustments: 5-21, 5-22, 5-29, 8-10, 9-2, 22-79, 23-110



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General comment: My car is a stock 91, with 27K miles, which had not had the timing belt replaced previously. The engine was very clean (except for one oil leak) and easy to work on. References to the service manual are for the 91 version. The following procedure is not the only way to approach the problem. The order of the steps in disassembly and then reassembly is not critical in many cases and can be altered depending on how you want to tackle the problem. My primary concerns with this project were 1) removing the crank bolt, 2) insuring that the camshafts never moved relative to the crankshaft, and 3) getting the timing belt on correctly. The crank bolt is fairly easy if you buy the Honda tool, which I did. The camshafts can be fixed using 5mm pin punches, as suggested in the service manual. To be 100% sure the timing belt went on correctly, I used a second set of marks instead of relying entirely on the factory marks. The factory camshaft marks are difficult to use because you are looking at them at an angle, and the crankshaft does not have the timing cover and pulley to align while you are putting on the belt. So let's get started. 1) If you are planning on pressure checking the cooling system right after the water pump is replaced, then the first step is to check your cooling system and tester before you start. This is described in the service manual. I applied 17PSI for about an hour and observed no pressure drop. 2) Decide on how the car will be positioned and jacked up for the duration of the project. I used a ramp under the left rear tire and a jack stand on the right rear with the right rear tire removed. This raises the back of the car about 7" which is comfortable for both working above and below. Having the rear raised also helps to drain the coolant. 3) If you are replacing the water pump, drain the coolant according to the service manual. This requires removal of the black plastic access cover under the car, which is held on by nine 10mm bolts. I have found if you drain the rear engine drain bolt, you get almost a gallon from the engine block. After that, the front engine drain bolt does not drain any coolant, so I skip that step. Tighten all drain bolts when finished. The manual says to replace the 2 aluminum washers (90471-580-000) on the center water pipe drain bolts. 4) It is not required that you change the oil on this job, but I did. At this point I drained the oil from the drain plug, removed the oil filter, drained the oil from the filter, then lightly reinstalled the filter back onto the oil pedestal. The oil filter will protect the oil pedestal during the project. Put a new crush washer on the drain plug and install. The new oil and filter will be added towards the end of the project. 5) On top of the engine, remove the strut bar which runs across the top of the engine. Although not required, I also removed the engine cover and the trim piece which runs the width of the car between the trunk and engine compartment. This opens up the engine compartment and provides better access. 6) Remove the air cleaner box completely. This is required to get to the transmission mounting bolt.



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7) Remove only the nut from the transmission mount bolt. The bolt stays in to continue to support the power train. To get better access to this nut, I also removed a bracket which supports the rear corner of the air box. 8) The service manual says to remove the coolant expansion tank, but leave the hoses attached. Three bolts will need to be removed. The tank just sits there with no coolant. I suspect this is necessary for tilting the engine. 9) Remove the oil filter pedestal, which is held on by three bolts. The upper two bolts are installed at the factory with sealant, so they are slow to come out, compared with the lower one. See the write-up by [LB] for a detailed explanation of removing these bolts. A small amount of oil will drain after removing the pedestal, so place an oil pan underneath. The coolant hoses will remain attached to the pedestal which will just hang there for the duration of the job. Moving the loose pedestal over slightly allows better access to the lower timing cover bolts, which is the purpose of having it loose. In hindsight, I think if I were to do the job over again I would detach the two hoses and the oil pressure wire and remove the pedestal entirely, although I do not know what other problems this might invite. It seems like the pedestal is still in the way a lot and you have to be careful that it does not get wedged while tilting and lowering the engine. If you do not buy two new upper bolts, for the oil pedestal, which come with sealant already on them, use HondaBond when putting these two back in during reassembly. Also, replace the figure "8" gasket between the pedestal and engine block. 10) Remove the "intake manifold plate" and then the "top cover" (Service manual pg 5-21). This is the plate and cover in the center top of the engine, between the head covers. The manual says to remove this, but I am not sure why. 11) Remove the two coil covers which are in the middle of each cylinder head cover. There are 4 bolts and 2 cap nuts for each cover. After the coil cover is removed, remove the brass colored cylinders on the middle stems that had the cap nuts on them. Note that the coil covers are marked FR (front) and RR (rear). They should be reinstalled the same way. 12) Remove some assorted items which are attached to the front head cover. These include the PCV valve, the shiny metal wire harness bracket on the drivers side, and the two plastic wire harness covers on the passengers side. One of the plastic wire harness covers is held on by the throttle cable bracket bolt. Once that is removed, both plastic harness covers can be removed, exposing two more bolts which hold the fuel line and another wire harness bracket. Remove these two bolts also. The 4 bolts removed in this step are all the same size. 13) On the rear cover, detach the air hose on the driver's end. 14) Remove body wiring harness mounting bolts. This step is only in the write-up by [LB]: "There are a pair of 10mm bolts that hold the engine wiring harnesses to the body of the car, one is on the angle bracket in front of the cooling fan, and the other is located directly next to the right side engine mount." This step is not in the service manual, but is necessary to tilt the engine.



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15) Remove the coils. There are 2 bolts for each coil. There is a connector on each coil which must be disconnected. These are easier to disconnect if you lift the coil up first, rather than trying to do it with the coil fully seated. The coil wire harnesses have a plastic frame which slides down over one of the middle stems (step 11). The brass cylinders that were removed earlier hold down the coil wire harness. After the coils are removed, the wire coil wire harnesses can be tucked away into the drivers side of the engine compartment. The coils are already marked RR and FR, but I also marked them by cylinder number to put them back the same way they came out. 16) Remove the head covers. In this write-up, "head covers" are the same as "valve covers", which is more common. I will stay with Honda terminology and refer to them as head covers. There are 4 cap nuts, one on each corner, and two nuts on the middle stems for each head cover which must be removed. The nuts on the middle stems require a deep socket. The O2 sensor connectors are attached to brackets held on by the cap nuts on the extreme front and rear passenger side. The O2 sensor connectors could have been detached in an earlier step, but I found it easier to remove the cap nut which frees up the bracket and then disconnect the two connector halves. The plastic tab to separate the O2 connectors is towards the lower rear and can be difficult to figure out. It may be easier to remove the metal bracket from the connector pair first. Each of the O2 sensor wiring harnesses has a wire which continues on around the backside of the head. On the front head, this wire goes to the A/C connector, mounted on the dipstick bracket. The A/C connector should be disconnected so that this wiring harness can be moved completely out of the way. On the rear head, there is a wire which goes to the oil pressure sensor on the oil pedestal. This one will not be disconnected, so this harness will tend to get in the way on occasion. After the 6 nuts on each head cover are removed, the covers can be gently nudged to break them free. Mine were stuck pretty tight from the dealer using a lot of HondaBond on a prior 15K service. Below each cap nut that was removed there is a rubber grommet. All 12 of these should be removed. These are not pressed into the head covers so if you lift off the head covers without removing the grommets first, one may fall into the engine and could be difficult to retrieve. The front head cover lifts out easily. The rear cover comes out by rotating the passenger side to the rear by 90 degrees first. 17) At this point, I did the step recommended in the [LB] write-up, which is to adjust the valves all the way out. This is just an extra precaution, in case one of the camshafts gets out of alignment with the crankshaft during the timing belt install. It will provide a little extra margin in preventing the valves and pistons from hitting. In hindsight, since I pinned all 4 cams, this was probably not necessary. If you are planning on adjusting the valves after the timing belt install anyway, this step is not very time consuming and it may give some peace of mind in knowing that you did everything possible to make this a successful job. During this step, be sure not to turn the crank with the pin punches in! Before I started turning the crankshaft to set the valves, I loosened the spark plugs by a few turns. This makes it easier to turn the crankshaft since you are not fighting compression, but



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leaves in the plugs to prevent debris from falling into the cylinders. I only completely removed the spark plugs right before installing the new belt, in accordance with the service manual. Also, prior to rotating the crankshaft, make sure the transmission is in NEUTRAL. It remained in neutral for the remainder of the job. I had thought of putting the car in gear to lock the crankshaft at #1 TDC during the belt install, but decided against it because I did not know how the transmission would handle the engine tilt while in gear. Many years ago I had a transmission bind up when I lifted the engine slightly off its mounts, and I did not want a repeat of that experience. With the head covers off, this is the first opportunity to see if your 5mm pin punches will work. Put the crankshaft at #1 TDC according to the service manual. There is a hole in each cam cover near the middle which should align with a hole in the camshaft below it. The hole in the cam cover is larger than the hole in the camshaft, which is about 5mm. I was lucky to find some 13/64" pin punches which were slightly undersized. I bought 6 of these and I found 3 of them that fit perfectly into the two rear camshafts and the front intake camshaft. The front exhaust cam would not accept any of the pin punches that fit on the other 3 camshafts. To solve this, I bought a 3/16" pin punch which did fit in the front exhaust camshaft. I believe the reason why the front exhaust camshaft was a difficult fit is because the cam cover hole was slightly misaligned with the camshaft hole. If you have this problem, find a pin punch that will fit, even if it ends up being a little loose. The pin punches will at least prevent gross misalignment of the camshafts and prevent valve damage. The precise belt alignment does not depend on the pin punches, as will be described later.

This is a picture of a pin punch seated properly. The tapered part of the punch fits snugly in the cam cover hole while the end of the punch is inserted about 1/8" into the camshaft. A word of caution regarding the pin punches. Make sure they are not too long, so that when you raise the engine they do not hit part of the engine compartment. After determining if your pin punches fit, REMOVE them from the camshafts and set them aside for now.



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18) Remove the alternator. This is the point where I disconnected the battery. I could have done this sooner, like the first step in the service manual, but since I was doing this job over several weeks I did not want the battery disconnected for that long. The write up by [LB] has a good description of this step: “Remove the plastic cover over the alternator pulley, (CHECK AND MAKE SURE THE BATTERY IS DISCONNECTED), then remove the large wire located under the rubber boot with a 12mm socket. Then loosen the 14mm nut for the belt adjuster, located on the rear lower side of the alternator. Using a 10mm socket adjust the alternator downward to remove the belt. Once the belt is off, remove the 14mm through bolt on the front side of the alternator. Lift it out of position, you will have to move it up and down a little to get it free. Once it is off of its’ mounting , remove the big green plug from the back and set the alternator aside." After this, I wrapped the rubber boot in electrical tape and then reconnected the battery. I only then disconnected the battery one more time when the alternator was put back on. 19) Remove the alternator bracket stiffener, which is held on by 3 bolts. Also loosen the A/C idler pulley bolt, then loosen the idler pulley adjustment, and remove the A/C belt. 20) Remove the right side engine mount. There are three 17 mm bolts to remove. Support the engine using a jack (see step 25), to relieve pressure from the side engine mount as it is removed. You may want to continue to support the engine from this point forward, or I saw no harm in having the transmission mount bolt hold the engine in place with the side engine mount removed. The service manual says to remove both mounts, THEN put a jack under the engine to tilt it. I do not think it is a good idea to have both the transmission mount and side engine mount removed without supporting the engine. I removed the right side engine mount from the car entirely, rather than pushing it into the body cavity as suggested in the service manual. 21) Remove timing cover bolts (Part A). There are 3 covers to be removed, the "lower timing belt cover", the "rear middle timing belt cover", and the "front middle timing belt cover". I will just refer to these as the lower, rear, and front cover respectively. It turns out that the order of removal of these bolts is not critical. I managed to remove most the bolts without tilting the engine. The service manual implies removing these bolts after the engine is tilted. My feeling was to do as much as possible without tilting the engine. The crank pulley does need to be removed to get to two of the bolts, so removing the bolts is interrupted by the crank pulley removal step.



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From under the right rear wheel well, remove the lower cover bolt which is located just above the oil pedestal:

Sorry for the bad picture, but it is the dimly lit bolt in the middle which looks like a half moon. You need a long extension to get to this one, but it is fairly easy. Follow the oil pressure sender wire to the rear slightly for the next lower cover bolt. You will have to lay on your back behind the wheel well to get to this one. You need a small wrench, either a 1/4" drive or box end.

Note the clip that holds the oil sender wire. It is not firmly attached to the wire so it may get lost after the bolt is removed.



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Moving up to the rear cover rearmost bolt, this can be easily reached from below the car. I had my catalytic converters removed so that may have helped. This may be the bolt that others have found difficult, perhaps because they attempted to get to it from above :

This bolt also has a clip for the oil sender wire which should be secured while removing the bolt. I had no problem removing these 3 bolts. [LB] comment: “For that rear bolt on the upper cover I remove the swaybar mounting bracket, w/ cats on. If you really want to see something hard to get to, do this on an OBDII car with 4 O2 sensors.” At this point, I took a break to remove the crank pulley. 22) Remove crank pulley. All I can say is BUY THE TOOL. The two parts of the crank pulley tool cost me about $100 discounted. I also needed a torque wrench that would go to 182ft-lbs, so I bought a new ¾" drive 600ft-lb torque wrench on Ebay for $200. This torque wrench has a 40" handle. You also need a ¾" to 1/2" drive reducer, a 19mm deep impact socket, and 14" of extension. I figure I spent $350 just to remove the crank pulley bolt, but it made the job very easy and I still have the tools to show for it. The crank pulley tool comes in two pieces, a handle and the part that fits the crank pulley. This is probably a good thing because I found it much easier to install the part into the crank pulley and then insert and tighten the handle. This is because you have to work around the suspension pieces to get the tool installed. With the car raised about 7", the tool handle will wedge onto the garage floor and hold the crank secure. This will not be at #1 TDC on the crank, so the crank will need to be positioned accordingly. Remember to always rotate the crankshaft CLOCKWISE to position it. In the pictures below you will notice that I had to remove the oil filter to get the tool to fit. I put the filter back on after the crank bolt was removed. [LB]: Or you can have the car higher an the filter is OK as is.



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This is a picture of the crank pulley tool installed. The next picture shows the torque wrench which I used as a breaker bar. I had read that only a 4" extension is required for the breaker bar. This may be true if the car is lifted high enough and the breaker bar can fit vertically in the wheel well. In my case, to clear the brake rotor and the fender, I had a total of 14" of extension, 9" of which was ½" drive. The extension was so long and the torque wrench so heavy that I used a jack stand to support the pivot end of the wrench.

At first I set the torque wrench to 180ft-lbs, to see if the bolt would break loose at the specified torque. No deal. Then I set it to 250ft-lbs and the bolt came loose, no problem. This bolt had not been removed since the factory, so it came off without a hitch. 23) Set the crank at #1 TDC and install the pin punches. The crank pulley will be removed from now until after the new belt is installed, so I wanted to set the crank at #1 TDC using the white



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pulley mark and the lower timing cover pointer. After using the crank tool to loosen the crank bolt, it will be necessary to rotate the crankshaft to #1 TDC. The problem is, rotating the crankshaft tightens the bolt slightly. So when you try and loosen the bolt again the crankshaft moves a little. Also, if you move the crankshaft ever so slightly counterclockwise, not all 4 pin punches will fit, due to a slight change in belt slack between the camshafts. To work around this, I rotated the crankshaft to #1 TDC, installed all 4 pin punches, then used the crank pulley tool with a shorter handle of 1' x 1'' pipe to hold the crank while I loosened the bolt again. I realized that there was some danger in doing this as it could violate the two basic rules: 1) never rotate the crankshaft counterclockwise, and 2) never pin the cams and rotate the crankshaft. The bolt loosened fairly easily so it was not a problem. 24) Remove timing cover bolts (Part B). With the crank pulley removed, the rest of the timing cover bolts can be removed. Behind the crank pulley there are 2 bolts on the lower cover which can now be removed:

These are the two bolts on either side of the crank. They come out easily. I had a small oil leak from the front head cover which explains why this area is oily/dirty. The oil ran along the edge of the timing covers down to this point, but I never saw leakage on the garage floor. The timing belt area was perfectly clean which shows why the timing belt cover gaskets are important. The remaining timing cover bolts are removed from the top of the engine compartment. All of these bolts are fairly easy to get to and remove. At this point there is still no need to tilt the engine.



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This is the upper bolt of the rear cover, which also has a wiring harness bracket attached. There is one more bolt in the center of the rear cover. When that is removed, the rear cover is loose. I moved it to the rear of the engine compartment, since the lower cover must be removed before the rear one is taken completely out. At the top of lower cover, below the alternator bracket, there are two bolts a few inches apart. These are easy to remove.

In the above picture, the second bolt is just outside of the field of view to the right. These two bolts are a little longer than the rest of the 10mm bolts which hold on the covers, so this should be kept in mind during reassembly. On the front cover, remove the dipstick bolt and the bolt in the middle of the cover, as shown in the picture below.



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The dipstick bolt is shorter than the other bolts. There are 3 bolts left on the front cover, the two on the upper corners, and one that is obscured by the shadow of the A/C idler pulley in the picture above. These bolts will easily come off with a ¼" drive ratchet. Once the front cover was loose, I just let it sit there until after the engine was tilted. Remove the A/C idler pulley. There are 2 long bolts on top and one short one on the bottom. The bottom bolt can be reached from below through the wheel well. You cannot get to the upper right bolt unless you loosen the pulley adjuster down until it is exposed. When you get the upper two bolts loose, you will notice that they will not come all the way out because the engine is not tilted. Now you must tilt the engine. 25) A jack is used to tilt the engine, as shown in the service manual. The service manual shows a cradle (attachment) under the oil pan to protect it. You are not actually supporting the full weight of the drive train, but rather it pivots on the front and rear motor mounts, which are near the center of gravity of the drive train. The heavier part is on the engine side, and I did not venture to see how far the engine would drop if it were not supported. You could probably use a piece of wood to put between the jack and the oil pan, to prevent denting the oil pan, but I built a wood cradle that put some of the force on the engine block where the oil pan attaches to the block, similar to the cradle shown in the service manual. Support the engine with the jack and lift it slightly to remove pressure from the transmission mount bolt. This may take a few tries, but the transmission bolt should slide out easily by hand. With the bolt out continue to tilt the engine. The service manual says to tilt it 5 degrees. I used the part of the alternator bracket which sticks out and bolts to the side engine mount (now removed) to gauge how far the engine had been lifted. You could lift it until the wire harnesses start to tighten up between the engine and body, but the subtle creaking and crunching while lifting was a little unnerving so I did not lift it as high as I could. I figured a 5 degree tilt is equivalent to about 2 inches of lift, assuming the point of measurement is 2 feet from the pivot axis formed by the front and rear engine mount (arcsine (2/24) = 5 degrees). I was most concerned with stress on the A/C lines to the compressor, as these are semi rigid and it is



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difficult to tell how much stress is being applied to these. Also, keep an eye on the oil filter pedestal which can get wedged between the body and engine while tilting it. 26) Continue timing cover removal. Remove the long bolts for the A/C idler pulley and the pulley itself now that there is more room from the engine tilt. The front timing cover should come out easily. The lower cover needs to have the grommet on the timing belt adjuster bolt removed before the cover can be taken out. This can be done with a screwdriver, but my grommet broke trying to slip it over the head of the bolt. This is a cheap part and should be replaced.

Timing bolt with grommet and dirty lower cover. The lower cover can now be removed. This was the most difficult one for me, probably because I did not have the engine tilted as far as it could. It needs to be rotated and then wiggled out. When I put the new cover on, I tilted the engine a little higher and it was easier to put in. Remove the rear cover now. 27) Timing belt removal. At this point the timing belt and water pump are exposed. This is when I quit for the day so that I could tackle the belt and water pump in the morning, fresh and alert. Before I quit, I lowered the engine and put the transmission mount bolt in. In the morning, I took out the bolt and lifted the engine again. For the timing belt swap I removed the spark plugs, as recommended in the service manual. Before removing the timing belt, I put a set of marks on the belt, all 4 camshaft pulleys, and the crankshaft gear pulley. With the camshafts pinned, this may seem like an unnecessary step, but I wanted to be 100% sure the new belt was put on right. There are a couple of problems with relying on just the factory marks. The camshaft pulley marks are difficult to see, and you cannot view them straight on. Here is a picture of the camshaft marks at #1 TDC:



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These are the factory marks on the rear side of the pulleys, which are easier to see straight on. The crankshaft position is difficult to verify with the crank pulley and lower timing cover removed. Here is a picture of the crank gear, with the timing belt guide covering it ( the brass colored piece). The guide piece is loose and will be removed during the timing belt install. I marked which side was front on this piece.

On the old belt, I placed a small mark corresponding to each pulley (4 camshaft, 1 crank) where the belt wraps around the pulley. I used a light color marker to mark the belt tooth, and a dark color marker on the corresponding tooth in the pulley. For the crankshaft gear pulley, it ended up looking like this:



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It may be difficult to see in this picture, but there is a black mark on the pulley also. For the camshaft pulleys, I marked the opposite side of the belt (drivers side), since you can see the belt teeth on all 4 pulleys on that side. The front intake pulley was marked as shown below:

With the belt and pulleys marked, the old belt can be removed. Before removing the belt, the tensioner spring should be removed. The service manual does not have you removing the spring, but if the water pump is removed, the spring must be removed. The spring comes off easily by hand. Loosen the tensioner bolt, and the belt will have slack in it. Remove in accordance with the service manual, starting with the rear exhaust pulley and working your way around. When the old belt is off, lay the new belt and old belt side by side, or one on top of the other, and mark the new belt EXACTLY like the old belt. You will be marking teeth. Verify your marks by counting the number of teeth between marks, both on the new and old. There are 241 teeth on the belt, the numbers should all add up.



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My 13 year old belt looked in very good shape. The only noticeable difference was that the old belt had a brownish hue to it. The lower one in this picture is the old belt.

Now its time to put the belts aside and change out the water pump. 28) Remove the water pump. The water pump is held on by 7 10mm bolts and 2 12mm bolts. These are Honda "special bolts" which the service manual says to replace. The reason they are special is that when you buy them they have sealant on them already. I guess you could use the old bolts and apply HondaBond, but I opted to buy the bolts and replace them. To remove one of the 12mm bolts, it will be necessary to move the tension adjustment pulley all the way to the left, without removing the tension adjustment bolt. It is not necessary to remove the tension adjustment pulley to remove the water pump. In the service manual, every reference to the tension adjustment bolt says not to remove it. The manual does not tell you what to do if you do happen to remove it. All 9 water pump bolts loosened easily for me but they were slow to come out due to the sealant. The following is a picture of the old water pump before removal:



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The 12mm bolt next to the tensioner pulley is at the bottom of the picture. This is the most difficult one to get to. If the coolant is drained from the block as suggested in step 3, there is not much coolant spill when the pump is removed. I placed a rag below the pump and it caught all of the spill. If you look inside the bolt holes, there is a lot of red sealant that stays, as shown in the picture below:

This is the end of removing things. Now it's time to start putting the car back together. 29) Install the new water pump. For reference, I have included the picture below showing the old style pump with the new pump. The new pump is at the bottom of the picture. Note that the weep



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hole on the new pump is a brass tube which sticks out of the lower timing cover, at the lowest point on the pump.

When installing the new pump, torque all bolts according to the service manual. The two 12mm bolts have a higher torque value than the seven 10mm bolts. The new replacement bolts which come coated with sealant are shown in the picture below:

30) Install the new timing belt. Follow the service manual in installing the new belt, starting with the crank gear pulley, then tensioner pulley, front exhaust pulley, etc. Match the crank gear pulley mark with the corresponding belt mark to start. This is done under the wheel well. I had trouble getting the belt to stay on the crank gear pulley with the marks lined up as I went above to put in on the front exhaust. A second person would be useful here. I ended up wrapping a plastic tie to hold the belt to the crank gear pulley as I went to the next step, then removing the



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tie. Wrap the belt around the front exhaust and then the front intake, then use a large black paper clip to hold the belt onto the front intake. The belt cannot slip off the front exhaust or rear intake due to a lip on those pulleys, so only one paper clip is needed during the belt install process. Before moving onto the rear cam pulleys, verify that the marks on the belt and pulleys line up on the crankshaft gear pulley and front camshaft pulleys. All four cams are held in place with the pin punches, so the factory marks should not be an issue. Here is the new belt on the crankshaft gear pulley with the marks aligned, and the engine is clean!

Also notice the wooden cradle I built to support the engine under the oil pan. Here are the front camshaft pulleys with the new belt and marks aligned:

At this point route the belt under the water pump pulley and onto the rear intake pulley. Check the marks on the rear intake pulley. The pin punch for the rear exhaust pulley will need to be



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removed now. There was no problem with this camshaft wanting to move out of position. I then advanced the rear exhaust pulley using a box end wrench by ½ tooth. I thought I had done this precisely but the belt would not go on the pulley. I set the pulley back by about ¼ tooth and the belt slid on easily. Install the tensioner spring. The tensioner bolt should still be loose. Most of the slack should be removed from the belt now. Go back and check the marks on all the pulleys, especially the rear exhaust pulley. Everything should be aligned.

31) Tension the belt. Remove the other 3 pin punches. Follow the service manual, take a box end wrench and take any slack out by applying counterclockwise pressure to the front exhaust, front intake, rear intake, and rear exhaust in that order. Hold on to each pulley as you go with your left hand to maintain tension on the belt as you go through the sequence. After the rear exhaust pulley is done push on the tensioner pulley to the right to remove all of the slack, then release the pulley to where the spring is maintaining the tension. Tighten the tensioner bolt, but not to full torque. When I had finished this step, I felt I had removed all of the slack in the belt. One last time, so you don't wake up at night wondering, check all of the marks that you put on the belt and pulleys. This is the last time that the extra marks will line up. (This is because the belt has 241 teeth and the crankshaft gear pulley has 22 teeth. The least common denominator is therefore 22x241, so you would need to rotate the crankshaft 5302 times to get the marks between all the pulleys and belt to align again.)

Put the crank pulley and crank bolt back on to rotate the crankshaft. Rotate the crankshaft clockwise one revolution until the white mark (#1 TDC) is up, by sighting through the center of the water pump pulley. Then continue rotating the crankshaft until the blue mark is up (the service manual says this is 9 camshaft teeth). Loosen the tensioner bolt 180 degrees. I did not see the tensioner pulley move when I did this, but I felt I had really taken out all of the slack previously. To be sure, I pushed the tensioner pulley to the right, released it, then tightened the tensioner bolt. Torque the tensioner bolt to specification. (My guess is that when the slack is removed initially at TDC, the camshafts are in a state of less tension, and this extra step at the blue mark is at a point where the camshafts apply more tension to the belt.)

32) Loosely install the spark plugs, to prevent debris from falling into the engine. They will be tightened after the valves are adjusted.

33) Add coolant and pressure check the cooling system. This step was suggested by [LB], to make sure the new water pump is on right and leak free before reassembling everything. I did this right after the new belt was installed, but if you have a leak you will wish you had done this before step 30, your choice. If HondaBond was used as sealant for the water pump bolts, you may want to wait before pressuring the system as it takes a few hours for HondaBond to fully set up. The coolant is added according to the service manual, closing each bleed bolt in sequence. The pressure tester is connected to the expansion tank. I applied 17PSI of pressure for at least an hour. Here is a photo of the pressure check:



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34) Remove the crank pulley and install the timing covers. Since rotating the crankshaft during step 31 slightly tightens the crank bolt, I used the crank tool with the shorter 1' pipe handle to hold the crank while removing the bolt. Putting the timing covers back on is basically the reverse of taking them off. However, I had more trouble putting them on than taking them off. I think this was partially because I used all new gaskets on the covers, which tends to push the middle covers away from the lower cover. I had difficultly getting all of the bolts to align. I suggest starting all of the bolts before tightening. I had all of the 10mm bolts on the 3 covers and when I tried to install the A/C idler pulley, the bolts would not go in. This is because the lower cover has two aluminum shafts which guide these bolts, one of which is shown here:

Since the lower cover is plastic and new, it had a flex to it which kept these shafts from aligning. My old original cover probably would not have been a problem. I had to remove the front cover and use a screwdriver to move these shafts into position. Next time I would install the A/C idler



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pulley on the lower cover first, before installing the front and rear covers. Be sure to place a new grommet over the belt tensioner bolt:

New lower timing cover, new grommet. The weep tube on the new water pump can be seen towards the left center of this picture. [LB] comment regarding step 34: “Go to NAPA and get a can of Silicone spray. If you spray the rubber seal on the lower cover the upper covers slip in easier, still a bit of a pain, but easier.” 35) After the timing covers are on, lower the engine and install the transmission mount bolt, torque to spec. 36) Install the crank pulley and crank bolt. To do this, you want the crank tool to be wedged on the floor angled towards the front of the car. There is a small space in the suspension which allows you to do this. However, I had to raise the car an additional 4-5" for the crank tool to fit with the handle against the floor. Once again, I had to install half the tool onto the crank, then attach the tool handle. I used the large torque wrench set to 180ft-lbs, and this step was completed without problem. Below is a picture of putting the crank bolt back on.



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37) The rest of reassembly is the reversal of the remaining steps above. After taking things apart, I found that putting things back together was easy and needed little guidance. I torqued every bolt to spec, except for a couple which I could not get a torque wrench on and had to do by feel. The torque ratings for each bolt are spread throughout the service manual, and I actually spent an evening extracting all of the information in advance so it would not interrupt my work. If you backed the valves out in step 17, you will need to adjust the valves, then torque the spark plugs in. I recommend adjusting the valves in any case. As a final check, before putting the head covers back on, I set the crank to #1 TDC and verified that all 4 pin punches fit as before. When I first used HondaBond to hold a rubber gasket in place, I found that it did a poor job of holding the gasket on initially. It takes a few hours for HondaBond to set up and hold the gasket properly. My advice is to try and plan for this if possible. The head covers, for instance, should have their new gaskets installed early on, not right before you plan to put them back on the engine. All in all, this was a very rewarding project and I am looking forward to doing it again in 10 years. I was amazed that through all of this I did not drop a nut, bolt, or socket into the engine which I could not retrieve. Gook luck and happy NSX motoring!


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NSX Timing Belt / Water Pump DIY - NSX Prime Timing Belt / Water Pump DIY By Gary ... crank bolt is fairly easy if you buy the Honda ... exposing two more bolts which hold the fuel