I have replace everything from the radiator to the sending units, With a 195 thermostat it seems to run at approx. 200 to 210 degrees, and that is with a little hole drilled in the thermostate, What is normal operating temperature, Also why would opening up the breathing of the vehichle make the intake manifold leak oil. I just dont get it....
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Re: 89 gmc 5.7 cooling problems
Hi! Screw-1 Some times I even get a little confused when the temperature gage in the cabs are not as accurate as we would expect. If you leave the radiator cap loose and put a thermometer in the coolant, or better yet ask around and find a infrared thermometer (you can leave the cap on). Check this reading at both ends of the radiator. Even if the water is at 210 degrees F, at the inlet from the top hose, as long as the coolant is at a lower temperature at the opposite end, this should be fine. If the radiator cap is leaking you may want to make sure the cap is ok.
If the gaskets are old, the pressure change with the breather off may indicate the PCV valve is not working properly. I believe the crankcase breather is still in the air breather. The combination of problems as well as excessive blow by will also cause leaks.
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Well, yes and no. Yes the relay or the computer could be faulty. But the computer is not going to ground the relay until the engine temp reaches about 225 degrees. Since the thermostat opens at 195 degrees running at 200 is normal.
when was the last time you changed out your thermostat and what temperature thermostat did you put in if it was 195 degree your not running to hot at 200 did you flush out your system clean it real good. check your drive belt (fan) not worn out or to loose for water pump, radiator core blocked or grille dirty, buy or have radiator cap tested it must maintain radiator pressure also check ignition timing.
Are you sure the head gaskets needed to be replaced was it to stop the leak? Go to an auto parts store leave a deposit and use the tool for free. One tool has a cap that fits on the cooling system and has a pump on top You pump the system up to 15 pounds and look around the engine and the radiator for leaks. This is what your repair shop should have done before they replaced head gaskets. Putt a meat thermometer in the radiator when it is cold start engine. Let run. Put hand on upper radiator hose when the thermostat is starting to open the hose will turn hot right away the thermometer will read 180 to 195 If the engine starts to over heat the thermostat is bad but if it opens the temp will slowly rise to 200 to 215 that will be fully open and around here the fan will turn on and cool the engine down( make sure the air is off or one fan will be on all the time) if fan comes on late replace temp sensor for radiator. If everything works the radiator is probably plugged
This is happening because you got it right!! It is perfectly normal for the temp gage to indicate those readings. Here's why...
The thermostat has to be heated to its set point, say 195 degree's, before it will open. While it is doing that the engine temperature sensor is "upstream" and it takes a little longer for the thermostat to react. The old thermostat may have had a lower set point or was just weak.
You may have been given the wrong thermostat. Either way, you can try a hotter thermostat. If the water pump has never been changed it might be time for a new one. I've already had one that was so old that the propeller inside had the fins rusted completely off and the bearings were so bad it was messing up the timing of the motor. The truck wouldn't idle. And guess where alll the rusted off propeller chunks ended up. . . that's right. In the radiator, heater core and the thermostat. I flushed that truck for three days in both directions to get all that scrap out of there. Good Luck. And if you still have the old thermostat you can always throw that one back in, just to see what happens.
If your temp is jumping between 150-200 degrees then I am guessing you have an air pocket in the engine where coolant should be. The air pocket moves through the engine and when it gets to the water pump, it looses prime and doesn't move the antifreeze which causes it to warm up. Take the radiator cap off the radiator when the engine is cool. Start up the engine and let it run until the thermostat opens up. As the air moves it's way to the radiator it will escape and you will see the antifreeze level go down. Watch it run and as the level goes down add antifreeze until the radiator remains full. Then make sure your overflow tank is up to the required level and I bet your heater works a lot better after that.
make sure antifreeze is full. run engine 10 min. verify engine is around 195 degrees. if not, try replacing thermostat. if it is running at 195, then maybe heater core problem or heater control not functioning properly