Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by daniel.wilson, Jun 10, 2002.

  1. daniel.wilson

    daniel.wilson Newbie

    Apr 16, 2002
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    What are your thoughts on running a lower temp thermostat on a TBI engine? I've heard some concern about the ECM's effectiveness if you do this. Nothing radical - I'm thinking 180 instead of the stock 195. At 195 the engine gets awful toasty under heavy load and I have to drive across the mountains and the Mojave this July...

  2. 95 Silverado

    95 Silverado 1/2 ton status

    Nov 9, 2001
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    Central PA
    this varies with where you are and how you use your truck. if your truck, with the 180 thermostat, still runs in the 185 to 200 range it shouldn't be a problem. the problem arises when a 160 deg. thermostat is used and the engine never gets above 170 degrees. the computer never sees it as being up to temperature and it richens the mixture, it also doesn't burn as well due to the lower cylinder temperatures.
  3. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

    Feb 17, 2000
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    Some good cooling info care of C&D

    See if the heat is coming from the tranny. The stock set up runs the tranny through the radiator. Need to keep that for the winter months. Add and BIG AUX tranny cooler and see if that helps with the engine temp. It will help a lot with making the tranny live. I personnaly like the stack plate coolers Like the B&M. Hayden also makes one and those are available at Pep Girls (at least here in GA they are) .They are more effecient so a smaller size for the same rating. I noticed more stable engine temps after adding the Haydens to both of my truck. The wifes 79 in partiular use to get really up to the worry zone running the A/C in stop and go traffic. The cooler seemed to drop a few degrees running down the road and takes a LOT longer to build heat than it did. Never seems to get as high. I also have a hayden tranny temp gages on both trucks. I was clicking 210's on the tranny (BAD) before the cooler and rarely see more than 160 after the cooler install.
    I would not go below 180 deg thermostat in a Factory FI truck. Same reason as the other person posted. The temperature rating for a thermostat is the point it's fully open. If your seeing over 200 then the lower thermostat is proably not going to change that.
    Now most people misunderstand antifreeze. I read a great artical about Anti freeze this past week in Car&Driver. Better educated me. Anti freeze does NOTHING to help with cooling. What it does is prevent freeze up and protect the system from corrosion. It does raise the boiling point also. However it lowers the cooling potential of the system. The Glycole (sp) is a poor heat transfer liquid. The artical said there is a 25% loss in effeciency of the system with a 50/50 mix. What you might try is to adjust your mix to say a 40/60 mix for the summer. This will increase the rate that the cooling system is able to transfer the heat. There is going to be a new coolant hitting the shelfs soon from Zerex. it's called G-08 or something. New cars already have the stuff and it's good for 150k. Their is a varient used in the trucking industry that is supose to be good for 300k then need a chemical boost and good for another 300k. It's pre mixed just pour it in.
    It is supose to have a better heat transfer property but still the freeze protection of what's on the shelfs now.
    Here is that artical on-line.
    Well after reading it it is not the same artical I and refering too.. Now I just got my C&D and it may be what I read is yet to come. This is the june eddition of the online but I think my latest tree copy is july or maybe august and a follow up to this. This artical regardless is excelent read.

    Heck I'll cut and paste it in here. Good stuff here worth the read.
    Patrick Bedard
    Top it up with green? Or orange? Which antifreeze?
    JUNE 2002
    Page 1 of 2

    It's 2002. Do you know where your corrosion inhibitors are?

    Some folks take the yawn approach to what goes on between consenting chemicals in the steamy privacy of a car's cooling system. Not me. And now my sensitivities have been further heightened. It was the weighty check I wrote to a welder for filling in some missing places in a cylinder head that did it. Funny how much aluminum went AWOL in the 30-some years since that engine left the factory, enough to leave gaskets hanging in midair.
    Funny? I laughed all the way to Coolant College. David Turcotte is the technical director for Zerex, the line of coolant products from Valvoline. He's a good-natured guy with "Dr." in front of his name. That means he knows everything. So I pestered him until he sent me a package of tech papers about antifreeze and agreed to hold still for follow-up questions.

    Modern antifreeze, he says, is 96-percent ethylene glycol, which provides the freeze protection, and four-percent additives. When you dilute that blend 50-50 with water, as the makers intend, you push down the freeze point to minus 34 degrees Fahrenheit. In normal circumstances, you also gain corrosion resistance . . . for a while. The freeze protection is permanent, but the additives are consumed in battle, so to speak.
    About half the additive is made of buffers to control acid buildup; the other half is corrosion inhibitors to protect metals.

    Perhaps the battle is already going badly in your car. A sticking thermostat can be an early indicator. The next stage: As detritus migrates through the system, it settles in the most confined spaces. If your heater blows cold, uh-oh.
    I was hoping that technology, as it marches relentlessly toward obsoleting everything I own, might also have created new antifreeze formulas that would bring forbearance and frustration to the chemicals frolicking under my aging radiator caps.

    Of course, no doctor writes the prescription before he considers the patient. The "old" antifreeze technology started in the '60s, improved in the '70s, Turcotte says, and was superseded in cars of the '90s by two new technologies. It turns out that an antifreeze transplant into older cars will work fine with one of the new types; the other will probably kill the patient.
    The old technology, a.k.a. "conventional," a.k.a. "inorganic," is green in color. Most of what you see on the shelves at Wal-Mart and AutoZone is conventional, including the yellow bottles of Prestone and the white bottles of Zerex.

    One of the new types is "organic acid technology," or OAT. It's orange. General Motors pioneered this chemistry starting with 1996 models in the U.S. and using the name Dex-Cool. Ford changed a few models to OAT, then backed away from it. VW, Audi, and Porsche are OAT users, too, but most others have resisted.
    Instead of OAT, most new cars now use a "hybrid" antifreeze that's formulated with both OAT and the silicate inhibitors from green (Japanese hybrids have different inhibitors). It comes in too many colors to pretend this type is color-coded. Interestingly, Turcotte says that as the materials improve for the white plastic overflow bottles of new cars, and they become less yellowing over time, automakers are becoming more venturesome in choosing coolant colors.

    The promise of OAT is long-life corrosion protection, on the order of six years/ 100,000 miles for the initial fill instead of the two years/50,000 miles that was typical with the old green stuff. The GM Dex-Cool formula works fine in systems designed for it. But it eats old-style radiators with lead solder, and the inhibitors work too slowly to protect against the sort of corrosion that happens so fast it actually erodes metal—for example, the cavitation likely in the imperfectly designed water pumps of older cars.

    "Cars born with green coolant shouldn't be changed to orange," Turcotte advises. It's also a bad idea to mix the two, although the result doesn't immediately turn into witches' brew.

    Coolant technology is driven by the makers of new cars to solve new-car problems (same with motor oil.) By the time a car gets old enough to be interesting to a collector, the latest antifreeze blends have moved on to protecting newer alloys and gasket materials. Fortunately, the aftermarket lives by catering to older cars.
    As for those aging characters we're keeping around as playmates, no matter what antifreeze we choose, and no matter how often we replace it, Turcotte says the best medicine is to play often. Coolant down in narrow crevices can become isolated, then overwhelmed by corrosion. Once it starts, the best you can hope for is a stalemate. You can't undo corrosion. To keep protection active in all the crannies, the system needs to be heated and circulated every 30 days, he advises. (Hey, Ed., more play days, please.)

    Obvious question: What about the water we mix in? He says modern coolants are designed to work with "reasonable" levels of hardness and chlorides in tap water. But magnesium and calcium, the hardness ions, unquestionably contribute to scale and deposits, which hurt cooling efficiency. And chlorides are corrosive. He says distilled water gets rid of all the worries. (It was 58 cents a gallon at my local Wal-Mart yesterday.) Or you can buy "predilute" coolant already mixed and ready to go.
    In my vision of purgatory, I'll be sentenced to changing antifreeze in all my cars, day after day, and some archangel with white gloves and a test tube will be checking the color of my flush water for contaminates. I have to keep flushing until he can't tell the drain-out from the distilled he carries in another tube as the control.

    Here in this life, I've always changed my coolant. I'm one of those guys who agonize over details. So the job takes a full afternoon for each car. I drain everything that comes out through the cocks, then top up with clear water, warm the engine, and run the heater to circulate fully, then drain again. Repeat at least three times.
    What to do with the drainings? I called the local pollution controllers. Antifreeze? Their book had no mention of it. After thinking a bit, however, they told me to put it out back in buckets and let it evaporate. Rocks evaporate at about the same speed.

    Old coolant "hanging up" in the system is a real concern, Turcotte says. But he also knows that nobody gets it all out.
    "We've done tests," Turcotte says. "If you open a drain cock or drop a bottom hose, you might get 50 to 60 percent out. The best machines, the new ones going into Valvoline quick-oil-change shops, get 80 to 85 percent." This is a manageable level of contamination, as long as the new antifreeze doesn't fight with the old.

    Next month: The doctor writes a few prescriptions.
  4. dyeager535

    dyeager535 1 ton status Premium Member

    Dec 13, 2000
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    Roy WA
    I agree with Grim...if the cooling system is not capable of keeping the vehicle cool, it won't be able to keep it at 180 either. It may delay the inevitable by a few seconds or minutes, but the simple fact is, your vehicle will run only as cool as the cooling system is capable of maintaining.

    The cooling system will "equalize" at whatever temp it can hold. For instance, if the radiator has just enough corrosion to slow coolant flow so that you see 220 on a long hill climb, thermostat temp (in the ranges we use) won't matter. A 180 t-stat will open at 180, but if the cooling system is inadequate, it will shoot right past that temp. 195 is the same way, it will just take 15 more degrees before it fully opens, and same thing, coolant temp will go as high as the system will allow. The difference is the lower "starting" temp, as long as the cooling system can maintain that temperature on flat ground.
  5. Triaged

    Triaged 1/2 ton status

    Feb 21, 2001
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    CA (LA/OC area)
    If you have the $$$ just buy a bigger radiator. If you don't use very little antifreeze and the recomended ammount of "Water Wetter" along with a 195* t-stat with 1 (or 2) 1/8" holes drilled in it. The holes make it easier to get all the air out of the systme.

    Grims disertation is also a good one. The idea about the tranny cooler is great.
  6. Blazer_Boy

    Blazer_Boy 1/2 ton status

    Dec 16, 2000
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    Sioux City, IA, USA
    Well sounds pretty simple. Take out your radiator and take it down to a professional shop to have it cleaned. Anything you can buy yourself to clean it will still not do as good as a job as they could do. A new fan clutch wouldn't hurt either. Personally I run 180 degrees because I've got a hopped up carburetored motor. I think they make aftermarket chips that can take advantage of lower thermostats. It bumps the timing and mixture up a little to give a lil' bit more power. /forums/images/icons/wink.gif

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