Atroubleshooting chartcan keep you fromskipping important di-agnostic steps, but real-world answers to spe-cific problems often lie

in the details. Attendees at the semi-nars and trade show of the 2000 con-vention of the National AutomotiveRadiator Service Association (NARSA)learned how to keep cooling systemsrunning cool in summer and pumpingheat into the cabin in winter—oneverything from cars to big rigs.

The news out of the show concerns anumber of topics—radiators, pressuretesters, thermostats and heaters. There’sa lot to cover, so let’s get on with it.

RadiatorsYou can’t afford mistakes with radia-tors, because today’s high-tech heat ex-changers are more expensive than ever.A late-model OE Taurus radiator listsfor more than $300, unless you can dobetter in the aftermarket. But you’vegot to be very careful about what youbuy. Taurus is one of the cars on the

road that’s more sensitive to radiatorperformance, and replacing one takesabout six hours of R&R labor! Eatingsix hours of labor is not something youcan afford to do if you intend to run aprofitable shop.

NARSA announced that it’s joiningthe industry consortium of MACS andthe Performance Review Institute ofSAE to provide technicians with per-formance, durability and fit guidelinesfor automotive heat exchangers. Theprogram, which the participants hopewill be operating within a year, is in-tended to rate all replacement heat ex-changers against OE specs for heattransfer, durability (such as salt sprayand pressure cycles for radiators) andproper fit (for example, does it go inwithout cutting and welding onadapters?).

With many radiators that are any-thing but an easy R&R, it’s doubly im-portant to avoid comebacks. So if youuse aftermarket radiators, you want toknow they’ll cool properly under alloperating conditions.

You can’t always tell a book by its

cover, nor a radiator by its size. Visteon’sPaul Verdile told the 2000 NARSAconvention that to meet its coolingperformance specifications in eventighter underhood packages, Ford isinstalling two new-design radiators.They may look like less, but actually of-fer equal or more cooling than heavy-duty designs.

A two-row radiator typically is ahigh-performance replacement for aone-row, but Visteon’s new 26mm one-row rad has dimpled tubes (whichbreak up the coolant flow for improvedheat transfer) and high fin density—19fins per inch. This compares to the tra-ditional 52mm-thick core—two rowsof conventional 26mm tubes and 10fins per inch. The new 26mm one-row,which is being phased into all cars andmany light trucks, beats the 52mm onheat transfer for all airflow rates and allcoolant flow rates except the lowest(see the graphs pertaining to the FordExplorer on page 24). However, overallperformance is equal at idle and betterfor trailer-towing and other high-loadapplications.

22 August 2000

Cooling Tips FromCooling Tips From

A new 36mm “B” tube—with fold-ed-over ends welded at midpoint, cre-ating two flow paths, in the shape of theletter B—is the heart of a new one-rowradiator Ford is now is installing in F-Series pickups and Expedition/Naviga-tor SUVs. It replaces the old two-row,52mm job and, except for one smallcoolant flow rate area where the two-row is slightly better, the one-row is farsuperior (see the graph on page 24).

The bottom line is, you can’t tell aradiator’s performance anymore just bylooking at it, or even by measuring orcounting the number of tubes. Untilthe new rating system is in effect, playit safe by sticking with the reputableaftermarket brands (or OE).

CuproBraze Brazing. The copperindustry hasn’t just watched its automo-tive radiator business go down the tubes(no pun intended). The Copper Devel-opment Association (CDA) has beenfunding development of lightweight,solder-free, high-performance and—most important—durable copper/brassalternatives to aluminum core construc-tion. The furnace-brazing manufactur-

ing process—called CuproBraze—isvery similar to what brought success tothe modern aluminum radiator. It usesa greater temperature range for manu-facturing effectiveness than convention-al aluminum processes. So it permitssmaller aftermarket manufacturers toproduce quality copper/brass radiatorsat lower cost.

Copper/brass still dominates theheavy-duty and low-price ends of theautomotive aftermarket. With Cupro-Braze, however, copper/brass radiatorsnow can compete in the same market asthe best automotive aluminum types.The pioneer in this area is UniversalAuto Radiator in Pittsburgh, a medium-size aftermarket manufacturer workingwith the assistance of the CDA.

Heavy-Duty Alternatives. It’s of-ten difficult to find aftermarket re-placement radiators for medium- andheavy-duty applications, which (alongwith cost) is why NARSA heavy-dutyspecialists can keep busy with repairwork. The pre-1995 medium-dutyFord trucks with Cummins engines,power takeoffs and alligator hoods re-

quire specific downflow radiators withPTO openings, and a new aftermarketsource—Behr Heat Transfer Sys-tems—introduced both this type of ra-diator and a crossflow with PTO open-ing for tilt-hood models.

Jeep Cherokee Radiator. Thereshould be no problem getting a radia-tor for a Jeep Cherokee, but there’s anexception—the right-hand-drive mod-els sold for postal delivery applications.This radiator is not the same as the onein LHD models (which won’t fit) andisn’t readily available for a low-volumemodel. An all-copper/brass radiatordrop-in replacement for the aluminumcore/plastic tank unit in the RHDCherokee was introduced at the showby Tanks ’N Tabs, a leading aftermar-ket parts supplier.

Pressure TestersSaving money on no-name parts ortrying to modify a “universal” radiatorto fit are mistakes a journeyman pro-fessional shouldn’t make. But todayyou can go just as wrong with stan-dard-duty parts for heavy-duty situa-

23August 2000

The annualNational

AutomotiveRadiator ServiceAssociation tradeshow provided its

usual blend ofgood general tipsand specific newapplications forkeeping things

cool whentemperatures

get hot.

BY PAUL WEISSLER

tions and last year’s parts on this year’smodel. Peak cooling system tempera-tures are on the rise—almost 300°F(with systems pressurized to 25 psi)since ’99 on some GM trucks, ChevyCamaro, Pontiac Firebird andCorvette with the new family ofpushrod V8s. These high-temperaturesystems are just the beginning, as thevehicle makers work to lower exhaustemissions.

The new GM systems have forcedshops to upgrade their pressure testersto the 30-psi level. But, although thecooling systems on these vehicles havebeen designed for the higher pressure,explained Gary Baseley, a Stant train-ing manager, at the convention, hecautioned techs not to go more thanabout 2 psi over the cap specification.Carelessly using one of the new testersand pumping up to 30 psi could “blowthe seams” on a marginal radiator orheater core, he said.

ThermostatsThe heavy-duty thermostat used to besomething you’d install for a customerwith a motor home if he were vaca-tioning in the mountains. With today’ssystems, though, it may even be stan-dard equipment on some vehicles,Baseley said. You can easily see thedifference between standard and

heavy-duty thermostats (the heavy-duty power valve is larger in diameterand the stat spring is much beefier),so don’t skimp against your or yourcustomer’s “better” judgment. A stan-dard stat valve will bounce closed andopen, and won ’t maintain stablecoolant temperatures, particularly un-der heavy loads. Is this enough to

cause overheating? Evidence says itcan be a major contributor to a cool-ing problem.

A number of vehicles with inletthermostats (at the coolant entry intothe block) have housings with thethermostats staked in place and O-rings or gaskets preinstalled. Thesestats, which have specific opening cal-

24 August 2000

COOLING TIPS FROM NARSA

Heat Transfer Performance Curves for 1-Row & 2-Row Radiators

As the chart on the left shows, the new one-row, 26mm dimpled-tube Visteon radiator outperforms two rows ofconventional 26mm tubes at all airflow rates. As seen in the chart on the right, except at very low coolant flowrates, the one-row Visteon radiator also outperforms the two-row in coolant flow testing. Overall, even at idle, theone-row radiator’s performance is better. These particular graphs apply to the Ford Explorer.

The new Visteon one-row, 36mm “B” tube outperforms the two-row, 26mmradiator except for one small area of the coolant flow rate chart. It’s clearlybetter in the more critical low-flow and high-flow rates of operation.

Heat Transfer Performance Curves forFord’s Light-Duty F-Series Pickups

Sou

rce:

Vis

teon

Sou

rce:

Vis

teon

40

35

30

25

20

15

10

5

0Hea

t Tr

ansf

er C

apac

ity

(J/s

/cm

^2

32

28

24

20

16

Hea

t Tr

ansf

er C

apac

ity

(J/s

/cm

^2

40

35

30

25

20

15

10

5

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t Tr

ansf

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apac

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(J/s

/cm

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Air Speed (m/min) Coolant Flow Rate (kg/min)

Coolant Flow Rate (kg/min)

1-Row, 26mm,Dimpled-Tube Design

(19 fpi)

1-Row, 26mm, Dimpled-TubeDesign (19 fpi)

2-Row, 26mmDesign (10 fpi)

2-Row, 26mmDesign (10 fpi)

1-Row, 36mm Radiator

2-Row, 26mm Radiator

ibrations, are used on sensitive en-gines. If they shift out of position dur-ing installation, however, they couldadversely affect the coolant flow pat-tern. The thermostats themselves areof the bypass type, so a replacementneeds the right-size valve to assureproper coolant flow. Aftermarketthermostat suppliers have added them

to their lines, so don’t ever try to digthe old stat out of its housing and in-stall a universal replacement. You’djust be asking for trouble.

Filling the SystemSome cars’ cooling systems have longbeen known as notoriously tough tofill—for example, the ones on the

Pontiac Fiero, Toyota MR2 and VWEurovan. Today, there’s hardly onethat’s easy, particularly with the relo-cation of the fill cap to a separatepressurized reservoir or—the newestlocation—in the upper radiator hose.Just jacking up the front of the vehi-cle until the rear bumper hits thegarage floor may not work. The carcompanies are using air bleeds in-creasingly, which you have to find andopen. They used to be strictly on theengine, and occasionally in an upperradiator hose or hose neck. Now theymight be anywhere, with the heaterlines becoming a popular spot. A newentry in the tough-to-fill category isthe Lincoln LS, and each of its twodifferent engines (a V6 and V8) re-quires its own special techniques.

You might think the V6 is routine,because it’s the familiar Duratec en-gine. But be careful, warned PaulVerdile of Visteon. Both V6 and V8models have one air bleed in a heaterline. On V6 engines only, there’s asecond one in the crossover pipe atthe top front of the engine. On V8s,there’s a coolant fill cap on the engine(under the beauty cover). You mightnot look for it because there’s also apressure cap on the coolant reservoir.

By the way, that beauty cover isheld on by three “Christmas trees,”

25August 2000

A competitive aftermarket line of crossflow (shown) anddownflow radiators for Ford medium-duty trucks withCummins diesel engines is being offered by Behr HeatTransfer Systems. These radiators include a power take-off opening in the mounting member, seen at the bottom.

When the thermostat is built into its housing, as shownhere by MotoRad of America (’99 GM V8 at left, ’95-on Nis-san Maxima and ’01 Pathfinder V6s at right), don’t try toget it out and substitute a conventional stat. The preat-tached O-ring/gasket is also part of the package.

Ph

otos

: Pa

ul W

eiss

ler

On Lincoln’s new LS, there’s an air bleed built into the heater hose locatedbetween the brake master cylinder and the coolant reservoir.

and only one is the type that pops offeasily. Figure on breaking the othertwo and have spares handy. (Guesshow we found this out?)

First, add as much coolant as youcan to the reservoir fill (slowly,please!). Next, remove the engine fillcap (which has a 10mm Allen head)and add as much as you can there.Reinstall both caps, but leave theheater line air bleed open. Run theengine at idle with the HVAC controlhead temperature set to 90°F. Whena steady stream of coolant flows fromthe heater air bleed, shut it, but letthe engine continue to idle for fiveminutes or so.

Open the heater air bleed again mo-mentarily to let any air trapped in thatarea escape. Top up the reservoir, runthe engine at fast idle, set the controlsfor 90° and check to see if the floorducts are blowing acceptably hot air. Ifthey are, you not only have some assur-ance that the heating system will beokay in winter, you also know that theair pockets are out of the cooling sys-tem, for good summer cooling. Let thesystem cool down and top up thereservoir again, if necessary.

Important caution: The Lincoln LSV8 has an electric auxiliary water pumpthat’s mounted in front of the radia-tor/condenser module (behind thegrille) and wired through a relay to thepowertrain computer. The computer,which also reads a pair of cylinder headtemperature sensors, can turn on thiselectric pump to increase coolant flow,if necessary, for periods of up to fiveminutes. If you ever need to check thepump, make sure it’s connected to asource of coolant—even for just aquick check. If you inadvertently runthe pump dry, it fails very quickly.

The computer also controls thespeed of the hydraulic fan motor via aduty-cycle solenoid valve that’s locatedbetween the engine-driven oil pumpand the motor. It’s a quiet design thatpermits infinitely variable fan speed,and has been used on the Lexus LS400 for years (and even briefly on theToyota Camry). But it’s expensive andmay be a one- or two-year wonder forthe Lincoln LS. After all, if the JaguarS-Type (the sister car on the same plat-

form) can use a premium all-electricfan at lower cost, why not Lincoln?

Other vehicles have their specialdesigns, as well. With the general low-ering of front ends, the radiator fillneck usually is off the radiator, theseparate, pressurized reservoir beingthe most popular alternative location.And on the new Dodge Dakota pick-

up, for example, the fill cap is on aneck spliced into the upper radiatorhose.

A new approach to purging air fromthe cooling system—adapted from a/cservice—was exhibited at the NARSAtrade show. Called the AirLift, it wasdeveloped by Uview Ultraviolet Sys-tems, a maker of a/c trace dye service

26 August 2000

COOLING TIPS FROM NARSA

On the Lincoln LS V8, remove the beauty cover as shown (probably breaking acouple of “Christmas trees” in the process, so keep some extras on hand) foraccess to the coolant fill cap. A 10mm Allen hex holds the cap on.

Connect your shop’s air line (red hose) to Uview’s AirLift, which uses a ven-turi effect to create vacuum and pulls down the cooling system. Then hook upthe refill hose (green), insert the other end into a container of fresh coolantand open the service valve. The fresh coolant will be drawn into the system.

kits and oil injectors. Basically, it’s aventuri-type vacuum pump, much likethe inexpensive a/c vacuum pumpsthat run on shop air, plus adaptersthat allow it to fit most cooling systemfill necks, including Japanese models.It’s intentionally designed to be some-what less effective than the best ofthat design, so it draws no more than

25 to 26 inches of vacuum. This isn’t adeep enough vacuum to boil evenplain water, so it pulls out air only.

HeatersIt may be midsummer, but the heateris a year-round part of the cooling anda/c systems. A customer may notice in-adequate heat more in winter than for

a/c reheat in summer, but a leakingheater still is a coolant leak you haveto fix. However, as ACDelco’s CharlieFewell told convention attendees,you’ve got to find the cause of a leak.If it’s corrosion perforation, there’s achance the coolant itself is bad, inwhich case the system will need acomplete flush and a good fill to pre-vent a quick reoccurrence. Also, checkfor coolant electrolysis. If a voltmeterprobe inserted into the coolant reads.3 volt or higher, there’s a defectiveground somewhere that can corrodethe radiator and/or heater core.

For packaging and line consolida-tion, Fedco heater cores are starting tocome through with detached neck tub-ing. If you lube the tubing O-rings withcoolant and install the necks and snaprings carefully, the O-rings should sealas well as brazed-in-place tubing. Be-cause the necks can rotate, they mayeven make the heater core, with itsprecisely bent tubing, easier to install.Lexus has used detachable necks withclamps for years without incident. AndFedco is a large manufacturer for theaftermarket (under the Modine brand)and OEMs.

You’re probably some time awayfrom your first Lincoln LS heater core,but this car’s HVAC system uses anelectronically controlled heater controlvalve instead of the traditional flapdoors. If you ever have to check thesystem, this NARSA convention warn-ing from Visteon is worth remember-ing: The valve’s harness connector ter-minals are very close together. If you’renot careful during service and create ashort circuit, you can kiss the HVACmodule goodbye.

The margins for error in cooling sys-tem service are getting smaller, as elec-tronic controls take over and the coolantruns at higher temperatures and pres-sures. But hey, it’s all part of the com-plexity of driveability diagnosis, andsome thermodynamics, too.

27August 2000

For a free copy of this article, write to: Fulfillment Dept.,

MOTOR Magazine, 5600 CrooksRd., Troy, MI 48098. Additional

copies are $2 each. Send check or money order.

Replacement heater cores from Fedco Automotive Components are starting tocome through with detached hose necks (right). The new design lowers costsby reducing package size and permitting some part-number consolidation.

With the O-ring installed against the flange on the hose neck, insert the detachedheater core tube into the core tank flange (left). Then secure the neck with asnap ring (right). Because the tubes can turn, installation should be easier.