Drove down to tampa yesterday with no problems. As soon as I got off the highway on the way back home and I hit the first red-light, I smelled coolant, and the temp gauge pegged red. Pulled over and there was no water in the car and no signs of a leak. Checked for water in the oil and there was none. Let it cool down filled it back up, ran it sitting with no leaks. Got about 50 miles down the road and the same thing happened again. This time it looked a little wet around the coolant tank. Filled it back up, still no leak and made it home just fine.

Any ideas? Thermostat sticking? Any help would be appreciated.

 

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I would verify that you are running the correct coolant (orange gm approved) and have the correct mixture. I've also seen some of the coolant resevoirs leaking at the seams. I would verify these two items just to be safe. If the resevoir is leaking, there is a repair you can do until you replace it.

 

looks like the thermostat is the culprit and i could also use a good flushing of the coolant system. has anyone here ever tried running their ls1 with no thermostat? used to do it all the time with a s/b chevy was curious how an ls1 would behave.

 

Have You Checked Your Radiator Cap? As An Engine Warms Upto Operating Temperature The Coolant Gets Under Pressure And If Your Cap Cannot Hold The Pressure It Will Let The Coolant Go To The Overflow Bottle. If You Are Not Running A Thermostat The Vehicle Will Run A Lower Temperature On The Highway Keeping The Coolant In The Radiator. I Would Not Advise Running An Ls1 With Out A Themostat Because The Computer Will Think The Engine Has Not Reached Operating Temperture And The Car Will Run In A Rich Condition.are Your Fans Coming On? I Need More Info To Be Of More Help

 

My car is doin the same thing and it's startin to **** me off, so help us out

 

fans are coming on. i replaced the 160 therm with a stock one yesterday and because of the computer being set at 160 they run alot.

after replacing the thermo i let the engine run for a while. the heater would not get hot and the coolant system started to make noise. right after that i watched the water start to overflow out of the coolant resevoir. shut the car off removed the radiator cap and let it sit for a while to cool off. went back out refilled with coolant, started it back up and it has been running fine the 2 times i have taken it out.

it was pretty clear that my thermostat was bad as it was all gunked up. i was thinking that i must have had some sort of air lock in the sysyem to make it sound the way it did and overflow that way. i still plan on replacing my water pump just to be safe.

 

really confused now. thought i would check the water level as the car has been running ok. went to pop the cap while the engine was still warm and noticed there was no pressure built up. water level was also low. added water, ran the car, went to pop the cap again and once again, no pressure. ok....i guess my cap has either been bad or went bad during this whole process.

replaced the cap and went for a drive. pulled back up at the house, shut off the engine, popped the hood and it was over flowing from the resevoir AGAIN. short of tearing into the coolant system i am not sure what elese to do. could a bad headgasket be causing this?

 

I am in exactly the same boat. Temp is soaring and water/coolant backing out of the overflow. Fans are working. I was going to change the T-stat today, but now maybe I will wait. I dont have a clue. I guess I could take it out and put it in some boiling water to check it.

 

mine is new and i reset my fans back to stock. i am so lost here. it acts like the water is backing out of the engine. it is violently coming out the overflow cap. i have the housing from the old thermo i may try it without a thermostat to at least see if it still backs up.

 

took the theomostat out and it still overflows. guess pulling the raditor and hoses is next to see if i am missing something. if all looks good i guess the water pump is next. still open to any suggestions.

 

Starting to sound like the water pump.

 

Could it be that you just have a big air pocket somewhere in there. After I swapped my cam I also had this problem. I had to drive it a few times before it finally went to normal. I ran the car with the heater on high and watched the level like a hawk. I left the cap off and all the air was starting to come out of the system. It took a while for it all to come out.

 

I'm going with door #3, slight head gasket leak. The pressure/temp from the cylinders is overheating the water and sending it out the overflow. Sometimes this can be verified by opening the radiator cap when the car is at operating temp and look for bubbles or foaming.

 

that door #3 is the direction i am leaning towards myself.