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Remove Thermostat: keep it cool?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by foxman, May 8, 2003.

  1. foxman

    foxman 1/2 ton status

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    If my temp guage is reading correctly, them My 90' K5 350 tbi is burning hott! I know these things cool differently than the carburated 350's so my question is, will removing the theromstat keep it cooler or will it risk dammage to the engine? Right now it wanders between 210 and off the scale on the hot side, when it is warmed up. I know the thermostat is good, I've tried a couple of different brands/temps. with the same result each time, and it does seem like the engine is getting pretty hot. So, will getting rid of it (the thermostat) for the spring/summer risk me amything?

    Thanks for your help.

    Jeremy.
     
  2. chevyracing

    chevyracing 1/2 ton status

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    It will run too cool and the TBI wil run a rich mixture causing loss of power and very bad fuel mileage.

    John
     
  3. foxman

    foxman 1/2 ton status

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    Any Ideas on how to bring the temp down? I seem to burn lots of oil when the engine heats up. I've heard of 7 lb. radiator caps and different mixtures. any ideas?

    Thanks
    Jeremy
     
  4. BrianDamage

    BrianDamage 1/2 ton status

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    sounds like something's wrong to me...it shouldn't be doing that

    what thermostat are you putting in them? most TBI's call for a 195 degree, not a 210

    have you checked your radiator for blockage? Water pump OK? Is your fan shroud installed? Fan clutch OK?

    I'd be trying to figure out how to fix it instead of rig it...less chance of you sitting on the side of the highway that way
     
  5. foxman

    foxman 1/2 ton status

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    Well, the thermostat is a 195, but it settles at 210 regardless of what temp I put in there. The waterpump is workin fine, the radiator is clean and antifreeze is nice and green (+ it is the right mixture) Fan, clutch and everything elyse check out OK. No smoke is detected to make me think it's a head gasket either. plugs burn nice and brown. I installed a secoend aftermarket temp guage because I thought the original was lying, but it seems to read the same. what would cause the guage to shoot up to the danger zone then all of a sudden kick back to @ 210? This has been happening for the last year or so... driving me nuts. Any other ideas???

    thanks for the help...


    Jeremy
     
  6. Pookster

    Pookster 1/2 ton status

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    You sound like you have a blockage- whether it be in the water passagesor somewhere else. Could just be an air bubble. If you let the engine warm up, you should be able to see coolant movement with the radiator cap off.
     
  7. DBLAZER

    DBLAZER 1/2 ton status

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    Sounds like to me that you have a bad temp gauge.
    I do not think it is a good idea to run without a thermostat. It is a very distinct possibility that the motor will run hotter becuase the water does not stay in the radiator long enougt to cool down.
    Go to autozone or whatever and buy an easy to install gauge and compare it to the stock one. I have found, in the last 3 Blazers I have owned, that the gauge can and will go bad.

    4 years ago I repleced the entire cooloing system. I drained the radiator, had it flushed (it is a 4 core by the way). I replaced the water with bottled water (purified) and added Water Wetter by Redline. The thermostat is very low, 180 if I remember right. I also replaced the radiator cap. My rig has NEVER run over 210. It normally runs at 190.
    4 years of rockcrawling in the heat of the summer I the heart of Texas, Moab, Oklahoma, and never an issue. It has even helped the life of my tranny wich runns very very cool.

    Nash
     
  8. BigBurban350

    BigBurban350 1/2 ton status

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    I run a 160 degree Tstat in my TBI truck and it runs excellent. Your engine is designed to run at around 180-210. /forums/images/graemlins/usaflag.gif /forums/images/graemlins/burb.gif /forums/images/graemlins/usaflag.gif
     
  9. Derf00

    Derf00 1/2 ton status

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    Go to a good radiator shop and have your radiator cap tested, a bad cap can cause some of the problems you have described.
     
  10. gumneck

    gumneck Registered Member

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    Well, I'll admit it here. I had a compact car(chevy of course) that was doing similar to what you are describing and I replaced the temperature sending unit. Problem fixed. Now I dont know if our blazers have them but maybe its an idea to check. Quick and inexpensive fix. Maybe someone can check their Hayne's book on it.

    Hope it /forums/images/graemlins/1zhelp.gif's.

    tom
    1991 Blzr on blocks.
     
  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    My recommendation is that you switch to a mechanical temperature gauge. They're far more accurate and reliable. I have cheapies that I bought at Wal-Mart for $20 or so in both of my trucks.
     
  12. wadinator

    wadinator 1/2 ton status

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    I don't know what year truck you having troubles with, but I used to have troubles with mine too. The factory temp gage would get up around 230-240 sometimes, and I knew that was way too hot. Of course, the first thing I did was swap in a new thermostat, but that didn't help.

    The next thing I did was install a new mechanical temp gage. I even went thru the effort of mounting it in the stock location. Sadly, it told me the same story the stock gage had been...230-240. Not good.

    The radiator was a brand new 3-core radiator, I had an electric radiator fan made to replace stock water pump fans on GM 350's and 454's that moved something like 5500 CFM of air thru it, and a new 180 thermostat. I was begining to think that there must be a partial block in the coolant lines somewhere, which would be a real MUTHER to find.

    But in one last ditch effort, I decided to try installing a 165 thermostat. After pulling the old stat out (that wasn't really that old in the first place) I happened to look at the new one a little closer and found out it was actually a 180 degree stat and not the 165 stat I had asked for. I was pee-oed, to say the least, but I threw it in anyways. From that time on, I've had to try pretty hard to get my truck over 200! She usually stays in the 185-195 range pretty well. The electric fans kick in at 200 and it drops back to 180 really quickly, like in a matter of a minute or two.

    I guess the point of that big stupid story is that new parts (like my thermostat) can misfuntion too. So make sure they're all good! /forums/images/graemlins/thumb.gif
     
  13. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Find somebody with a Scan tool and see what the ECU says the temp is.
    Did you put the wrong water pump on? Your truck should have a serpentine belt and it uses a Reverse water pump. It looks identical to a regular water pump but the fins are a different direction because the serpentine belt runs it backwards of the trucks before it.
    IOs it fluctuating from 200-red and back every few seconds? that's a water pump problem as well. There is cavitation in the cylinder heads and it lets a air pocket form where the temp sender is.
    Are you having any other wachy problems like gages bouncing when you use the turn signals. Thats a cab ground problem.
    Did you trace the wires under the hood and make sure that the temp gage wire isn't laying against the exhaust manifold? Direct ground is pegged on the meter.
     

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