CheezHed21

After about thirty minutes of continuous run my coolant temperature gauge is closing in on the red line. The temp gauge says the engine is overheating. But the engine doesn't have any of the symptoms. I already replaced my thermostat and drained and refilled the system. I assume it's either a faulty coolant temperature sensor or a faulty coolant temperature gauge, but the possibility of overheating my engine and causing severe damage is too risky. How do I tell the difference between a faulty sensor and/or gauge and an actual overheating engine? If I just unplug the sensor I won't know anything, so I can't do that.

Help!

LS6427

iTrader: (2)

Simple. Go drive it.....the second you see it hit the 240*F mark....pull over, shut the engine off and pop the hood.

If you can keep your hand on top of the intake and keep it there.....you are not running hot. Change the temp sensor.

If its too hot to keep it on there for a couple seconds.....you are really overheating. Your tstat is probably sticking closed or partially closed.

Or go buy a $25.00 laser temp gauge and pull over and hit the head right near the sensor and see what the temp reads.....

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CheezHed21

I can already say without taking it for a test drive that the intake manifold was hot. It's snowing here and some snow fell on the engine when I popped the hood. It sizzled and boiled on the intake manifold right below the throttle body. I just had the damned T-stat replaced last week! Now I get to do it again!...

I drained and refilled the coolant again. When I ran the engine with the radiator cap off I could clearly see the coolant flowing and pumping. From my experience, thermostats are faulty half the time. I just have bad luck with them. At least it's a cheap fix.

Related question, if I change the T-stat myself, which I almost never do because the damned things are hard as hell to seal, would this seal work? Found it online...

http://www.farmandfleet.com/products...l#.UQymIxG9KSM

LS6427

iTrader: (2)

When you had the radiator cap off and saw the coolant flowing while the engine was running....was the engine cold?

If it was cold then the tstat is stuck fully open.

And no....you need a gasket that works with the LS1 style tstat housing. It's a black thin round gasket. Rubber only.

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LS6427

iTrader: (2)

Oh, and just below the throttle body is all metal....and it gets very hot there....snow should kind of sizzle on it.

If the snow clearly hit the black plastic intake.....and it actually sizzled......that would have to be real real hot......

Do the hand test on the black plastic right in top.........next time you see the temp gauge at 240-250.

And how fast does it go from say 185 to 250........?
Few seconds.......or a few minutes?

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wssix99

iTrader: (5)

Great resource and test procedures here: http://www.wellsve.com/sft503/Counterpoint2_2.pdf

BlackLS1Bird

iTrader: (2)

I had my temp gauge reading really high one time and it was the sensor. Changed it and everything was good again. Those resistance type sensors only last so long because of the heat cycles they go through. My plan is that every time I change a thermostat, I also change the sensor.

abs321

i noticed when i stop for car for 2 minutes idle it reaches overheating temp but then i start cruising the car a bit it gets lower but still over 60% then i noticed it was a bad water pump it boils when u turn the car off and it was leaking from water pump gaskets too
changed the water pump then everything is ok i hope this helps☺️

johngrn

I also a stock 98 TA with the same problem and has take me many year to figure out what is going on, the temp of 227 with 16 lbs in radiator) is a factory setting the way it works is at driving speed above 30mph the temp come down to about 212f the when in traffic or running below 30 mph it will go up to 227f + this is made to work with the catalytic converter to keep emission under control, Now if you want to have your car run cooler there are two things that must be done get 160 thermostat ( I bought mine at oreillys your is removable from the housing on ls1) and you have to have the fans settings reprogrammed, on this car the 160 thermostat controls the lower end temp @160 and the FAN SETTING controls the high end setting @ the 212f and the 220f

johngrn

I also a stock 98 TA with the same problem and has take me many year to figure out what is going on, the temp of 220 is a factory setting the way it works is at driving speed the temp come down to about 212f the when in traffic or running below 30 mph it will go up to 220f + this is made to work with the catalytic converter to keep emission under control, Now if you want to fix this problem there are two things that must be done get 160 thermostat ( I bought mine at oreillys) and you have to have the fans settings reprogramed, on this car the 160 thermostat controls the lower end temp @160 and the FAN SETTING controls the high end setting @ the 212f and the 220f

stilealive

Going to a 160* t-stat will make some cars run hotter and overheat. There's more to keeping coolant cool than changing the t-stat and fan settings.

My engine runs cooler with a 180*.

If you use a 160* and there something else causing your coolant to get hot, there will be a point reached where that 160* will gradually begin to not close all the way. Then it will remain fully open and its all over....you will overheat. Coolant needs more time to sit in the radiator to cool off before going back into the big metal coolant heater (the engine).