20 August 2010

COOLING SYSTEM

In all the years weve been re-porting on cooling systems,weve never seen the antifreezesituation more confusing. Whilethe dye colors being used seemto have exhausted the rainbow,we hope most technicians have learnedthat the color of the antifreeze dye hasnothing to do with the corrosion protec-tion formula for the ethylene glycol-based fluid. At each individual car man-ufacturer, the procedure is to change thedye color of its assembly line coolantwhen the formula is changed, althoughHonda changed from dark green to darkblue while retaining the same formula.

The what-to-use issue became evencloudier this year as Ford began a mul-

tiyear changeover to a single worldwideantifreeze. It had a choice of three for-mulas that its currently using on do-mestic products. Well spare you thesuspense: Ford is moving to the orange-red OAT (organic acid technology) an-tifreeze/coolant it uses in all of its Euro-pean vehicles, and that tells you thateven more Ford of Europe engineeringis coming here. At present, we have theTransit Connect panel van importedfrom Turkey, and the Fiesta economycar, engineered in Europe, thats beingbuilt for the North American market ina plant in Mexico.

Fords coolant reservoir labeling addsto the confusion. The label on the3.5/3.7 V6s on the Lincoln MKT says

Relearning the Alphabet:

MAKING SENSE of the

COOLING SYSTEMSCENE

BY PAUL WEISSLERIf youre looking for a one size fits allstrategy, your best bet is to stick withtube socks and steer clear of moderncooling systems. These systems wonttolerate substitution of inappropriate

orworseincompatible coolants.

Ph

otoi

llust

rati

on: H

aro

ld A

. Per

ry; i

ma

ges:

Th

inks

tock

21August 2010

no orange, even though Ford is in theprocess of converting to it. Its not thecurrent factory fill, and Ford doesntwant the present OE protection formu-la adversely affected.

The new F-Series heavy-duty modelshave two new U.S.-built V8 enginesa6.7L diesel and a 6.2L gasoline version.The new Mustang also has a new gaso-line V85.0L, to go with the 3.5 V6.These new engines are factory-filledwith the OAT coolant. And in caseyoure wondering, that OAT is a Dex-Cool clonebasically what GeneralMotors has been using since 1996.

One worldwide coolant makes a lotof logistical sense, and even saves Fordsome money. But using an OAT coolantdoes require a lot of specific engineer-ing, as GM learned, so Ford is goingslow. The company actually will phaseout engines (such as the 4.6 and 5.4V8s) rather than attempt to convertthem from the yellow dye hybrid OAT(H-OAT) it has been using in most of itsdomestic products since 2002.

This go-slow approach should tellyou that, beyond any doubt, you should-nt use an OAT coolant in any Fordproduct for which it was not specificallyengineered. Thats not our statement(although we believe it); its from Ford,and for good reasons. Also, dont use itwhere it may eventually gofor exam-ple, in the 3.5/3.7 V6s.

Advertising claims by some antifreezeproducers to the contrary notwithstand-ing, these OATscertainly DexCoolare not universal coolants. You shoulduse them only in General Motors prod-ucts, VW/Audi through the 2009 modelyear and Ford vehicles where the reser-voir label says so. After all, if it didntmatter, Ford would put an OAT an-tifreeze in all of its engines, includingthe 4.6 and 5.4L V8s. Obviously, it doesmatter. Furthermore, you should use anantifreeze that isnt just compatible withwhats in the system, but one that has asimilar inhibitor formula (mimics it), sothe inhibitors in there are boosted,rather than diluted by something else.

As a result, the only recommenda-tions we cite are in that category. Forexample, we wouldnt advise an Asianformula that didnt contain phosphate,or in most European cars (OAT-fills ex-

cepted) an antifreeze that didnt containsilicates. Nor would we consider a con-ventional American green formula withboth silicates and phosphates for thosevehicles whose formulas contain sili-cates or phosphates.

Heres the background on these rec-ommendations and the issues behindthem:

Silicated H-OAT antifreeze uses thepopular inorganic inhibitor silicate,

which not only protects aluminum verywell, but also provides fast protection.Thats particularly important in case awater pump cavitates (imploding coolantbubbles that pockmark the chamber).When left unprotected, the pockmarkscorrode, causing the pump to fail). Theorganic acid is called benzoate, and its ef-fectiveness in combination with silicatesis well established. The antifreeze in-hibitor package also contains a copper/

MAKING SENSE OF THE COOLING SYSTEM SCENE

Heres a display of just some of the antifreezes in use today. From left: conven-tional American green; a branded DexCool; Prestone (the DexCool formula withoutthe label); Toyota red (standard-life antifreeze), with a formula typical of Asiancars pre-long-life; Zerex Asian Long Life; Zerex G-05; Mopar G-05 with orange dye(dealer jug); and Mercedes-Benz G-05 antifreeze (dealer jug). Stocking any five ofthe eight would provide adequate coverage for an independent shop.

22 August 2010

BMW and Volvo have been usinghybrid formulas based on lowsilicates and 2-EHA organic acid,and for 2010 VW/Audi is now usinga similar formula. Here we see nogreat aftermarket alternative for adrain & fill. For premium makes suchas these, however, the customer islikely to be willing to pay for a jugfrom the dealer.

VW/Audi and Volvo have nospecified coolant drain intervals. Dothey think their antifreeze lasts for-ever? And what about Mercedes,which has a 10-year/150,000-mileservice interval for the G-05 silicatedH-OAT antifreeze it uses?

The answer for VW/Audi and Vol-vo is that these companies do telltechnicians to change the coolant ifits dirty, but they apparently realizethat a coolant hose or two will needreplacement in perhaps a 4- to 6-year period, during which servicethey recommend a coolant change.At Mercedes, the coolant reservoircontains a bag of silica gel (to absorbmoisture), and particles of that ma-terial slowly leave the bag and re-fresh the antifreeze silicate content,extending its life. And like VW/Audiand Volvo, eventually a hose has tobe replaced, so the coolant will haveto be replaced, too.

European Specialty Formulas& No-Drain Recommendations

Ph

otos

: Pa

ul W

eiss

ler

brass inhibitor, either BZT (benzotria-zole) or TTZ (tolyltriazole), to protectany small copper parts used and any ser-vice parts that may be installed later.

Ford has used this silicated H-OATformula since the 2002 model year,Mercedes even longer (over 20 years)its the yellow OE coolant, the aftermar-ket equivalent being Zerex G-05 orHavoline Custom Made. Chrysler alsouses it, but the OE stuff has orange dye,

so dont confuse it with DexCool. Thissilicated H-OAT antifreeze also containsnitrite, which enables it to protectdiesels against cylinder liner vibration-caused pitting. Thats one thing Mer-cedes likes about it, as does Chrysler forits Cummins diesel engines.

The third coolant also is an H-OAT,but this onepreferred by Asian car-makersuses phosphates instead of sili-cates. Phosphates quickly reprotect a

cavitation-pockmarked pump, plus theAsian makers use BZT or TTZ to protectcopper/brass. In Ford and Mazda prod-ucts, particularly the 3.5/3.7L V6s, thedye is deep green. Other Asian makersmay have pink dye (Toyota/Lexus) orblue (Honda). The organic acid is seba-cate, as Asian makers refuse to use thechemical ingredient ethyl hexanoate (2-EHA), primarily because it affects gasketmaterials. They also dislike silicates be-cause in some tests they run, silicatesform a gel that could plug passages. Gelformation and plugging is not particular-ly a real-world issue with the low silicatecontent in the silicated H-OAT an-tifreeze. In fact, the only cases weveseen where there was real plugging (asopposed to relatively minor deposits)were with higher silicate content in olderantifreeze formulas. And even that gel-plugging was rarely seen, unless a vehiclehad been sitting unused, in which casethe silicates may have dropped out. Sili-cate dropout, however, also may occur ifthe antifreeze has been sitting on theshelf for a few years or more.

For overall protection, though, sili-cates beat phosphates. But to maintainthe original Asian antifreeze protection,you want the phosphated H-OAT.Theres finally an aftermarket formulayou can buyZerex Asian Long Life.

The coolant reservoir for the 3.7L V6 in a Lincoln MKT is shown in the left photo. The coolant is deep green, but its a stan-dard Asian Long Life formula. Note the label below the pressure cap, which has a Do Not Use symbol through orange an-tifreeze, although that engine will eventually be changed over. The right photo shows the coolant reservoir for the newFord Transit Connect panel van and its 2.0L Four. The label warns against using deep green (Asian phosphate-content hy-brid OAT) or yellow (Fords low-silicate hybrid OAT) antifreeze. Only orange coolant is approved.

This water pump had been pockmarked by cavitation and not reprotected, sothe chamber continued to corrode. The impeller is both pitted and polished bycavitation. The pump had 100,000 miles on it, but thats not a lot today.

23August 2010

The dye color is a shade of pink, but itmatches up well chemically with all theAsian vehicle antifreezes, regardless ofcolor. In fact, its the same formula thatsused by Hyundai, despite the differentdye color (Hyundais is blue-green).

No antifreeze is perfect, and that cer-tainly includes an OAT. The OAT con-tains 2-EHA, and usually in combina-tion with sebacate. So the formula isthese two organic acids, plus TTZ forcopper/brass.

OAT antifreezes last a long time, butalso take a long timeabout 5000milesto establish protection for cool-ing system passages. And the slow actionmeans they cant quickly protect waterpumps that are pockmarked by cavita-tion. So the pump and cooling systemmust be engineered to minimize cavita-tion, which is primarily a high-load issue.The chemical 2-EHA causes leaks in sil-icone rubber gaskets and Nylon 66 gas-ket carriers, so they must be avoided.

Because OAT antifreezes protectbest when the system is absolutely full,which means the coolant is in contactwith the walls of the system, maintain-ing a full fill becomes another issue.

This is particularly important with cast-iron engine blocks, where a low levelcauses rust blushing on cooling sys-tem walls, a pickup of the rust fromcoolant flow and deposits in the radiator(see the photo on page 26).

Although Ford cars have all-alu-minum engines, the Super-Duty F-Se-ries truck has the new 6.2L gasoline V8and 6.7L diesel V8, both with cast-ironblocks. Low coolant level also can affectaluminum heads, so always check thecoolant level whenever a vehicle is in forservice. If it has a pressurized reservoir,you can check that level easily. If thepressure cap is on the radiator, remove itto make sure the system is topped up; ahigh level in an atmospheric reservoirdoesnt guarantee the system is full.

Ford designed all of its European en-gines to minimize water pump cavita-tion, and where possible, it did the sameon its U.S. engines (the 3.5 and 3.7LV6s and the I-4s), so they could livewith the OAT antifreeze. No such luckwith the 4.6/5.4L V8s, which, along withthe gasket issue, is why they continue tohave the silicated H-OAT until thoseengines are history.

THE COOLING SYSTEM SCENE

24 August 2010

We know lots of shopsthat still use convention-al American greena mix ofsilicates, phosphates, benzoateand either BZT or TTZ, plusother inhibitors. Its a short-lifeformula, okay for 2 years/30,000miles or so. But the shops justtake out the old coolant andfill with a name-brand Ameri-can green.

Although its the appropri-ate choice for older Americancars, it doesnt necessarilywork that well in combinationwith the new formulas, de-spite the commonality ofsome ingredients (in fact amuch higher silicate contentthan the H-OAT formulas)theres just too much in theoverall balance of the formulathat also is different.

So what about the completechange over? Problem: With

Conventional Green and Drain & Fill

If an older car was factory-filled with con-ventional American green antifreeze, thatsthe logical service coolant. Drain as muchcoolant as you can and refill the systemwith a 50/50 mix of antifreeze and distilledwater. A nice thing about air-bleed funnelslike the one shown here is that you can pourin the antifreeze, and switch to distilled ordeionized water at the halfway mark.

Circle #13

Ford has been particularly sensitiveto guarding against low coolant level,which was responsible for the rustblush plugging of radiators on someGM cast-iron V6 and V8 engines.

Most Ford engines, not just the cast-iron types, have cylinder head tempera-ture sensors, and in some cases on en-

gines already equipped with coolanttemperature sensors and even low-coolant-level sensors in the reservoirs.Ford in particular uses the head sen-sors, for a low coolant strategy that putsthe engine into a limp-along mode toprotect against warping or worse.

Ford also was alert to the cylinder

25August 2010

the convoluted cooling system pas-sages on todays engines, the onlyway to get all the old coolant out isto remove the engine (and heatercore) and turn it upside down. Vehi-cle manufacturers will tell you thatthe best drain procedure may re-move only 60% of the coolantonsome vehicles, maybe 80%. Thebest drain & fill machines will dosomewhat better, but are likely tofall a bit short of 90%, and evenlower with some systems. If youdrain the cooling system well, thentop it up with water, warm up theengine and then let it cool, drainagain, then refill, etc.three timeswill get close to 90%.

In most cases youll be leaving in20% of the coolant, maybe a lotmore if you dont have a premiumdrain & fill machine. And howmany systems are that easy to refill,even with a vacuum fill kit, or withthe bleed valves opened? So if you

mix, you shouldnt be surprisedwhen a heater core corrodes andleaks from bad coolant. The issue isless the formula (if youre thinkingin terms of a 2/30 service interval).But most people go a lot longerthan that, and in addition may dotheir own change, which consistsof draining a couple of quarts ofcoolant from the radiator and nomore. So theres a likelihood of alot of bad coolant remaining in thesystem. When you get a shot at thevehicle, go for the best you can do,hopefully using a machine.

And just because its an old car,dont think it isnt worth the dollarfor distilled or deionized water. Ifthe motorist is investing in coolingsystem service, hes not unloadingthe car so fast, and the small in-vestment in mineral-free watercould be the extra step that savesthe cooling system from an expen-sive failure.

Asian Extended Life aftermarket antifreeze is a phosphate-content hybrid OATthats suitable for use with all Asian systems, although when mixed with factoryfills, its pink color may discolor blue and deep green dyed coolants a bit.

Circle #14

liner pitting issue. You cant use nitritein the OAT formulationits a bad mix-ture. So the new 6.7L diesel was engi-neered to minimize piston slap. Thesmall amount of protection an OATcoolant provides will be enough to pre-vent liner pitting, Ford says.

An important service lesson, in addi-tion to continuing with whatever is theFord OE antifreeze: Service parts couldbe an issue, particularly water pumpsand those gaskets that seal coolant pas-sages. Many head gaskets, for example,have silicone sealing rings for the coolantflow holes, and you wouldnt want to usethem for engines with an OAT coolant.Ford has all-metal gaskets for the OAT-equipped engines, MOTOR was told.

Aftermarket suppliers have beenalerted to the water pump (design forminimum cavitation) and gasket issues,and the reputable ones surely will engi-neer appropriate new parts. However,you just might get an aftermarket gasketthat was made for the 3.5/3.7 V6s be-fore the coolant change, and if it weremade with silicone rubber (or with Ny-

lon 66), it might create a service issuewhen Ford changes the V6 to an OATcoolant. So a coolant-passage-sealinggasket for a Ford engine that has beenchanged over to an OAT antifreeze

should be an object of caution, if thegasket has been sitting on a parts job-bers shelf for years.

Ford is not pushing the service life en-velope very much with the OAT coolant.

MAKING SENSE OF THE COOLING SYSTEM SCENE

26 August 2010

Circle #15

The heavy rust deposits in this GM radiator are a symptom of a low coolant levelin 1996 and later pickups and SUVs with cast-iron engine blocks.

Its 6 years/100,000 miles for the factoryfill and every 3 years/50,000 miles there-after. On the new diesel its 6/105 for thefactory fill in normal service and just2400 hours/60,000 miles in severe ser-

vice (lots of idling, heavy loadsthe usu-al truck stuff). The diesel service intervalthereafter is just 3 years/45,000 miles innormal service, but 1800 hours/45,000miles in severe service.

A likely reason for the shorter serviceinterval after the factory fill is replacedis that Ford uses deionized water forthe 50/50 mix on the assembly line, andalthough it would like to see the after-market do the same, it obviously isnttaking bets that will happen. Because anOAT coolant takes about 5000 miles toestablish protection, using pure waterfor the factory-fill mixture obviouslyhelps protect the system until the mix-ture has done its job.

But we also would note that antifreezelasts longer if the water with which itsmixed is free of minerals and other con-tent. You also can use distilled water forservice, if thats easier to get. A gallon jugis maybe a buck or so, and we think its agreat investment for any well-maintainedcooling system. Its also a plus to whichyou can point proudly when you hand acustomer the bill and explain why yourshop does a better job.

27August 2010

This article can be found online atwww.motormagazine.com.

To prevent damage, Ford has used cylinder head temperature sensors to trig-ger a limited-engine-operation strategy when low coolant level issues are de-tected. The sensor shown (arrow) is in a typical location in the valley of a V8.

Circle #16