hey guys, I just picked up a 99 zr2 with 125000 miles on it. I had an overheating issue and noticed the coolant was low, so I decided to do a full cooling system flush. It all came out pretty clean, I didn't see any chunks or sludge coming out at all, and I flushed it 3 or 4 times, and used the cleaner as well. The water coming out was crystal clear by the end, so I refilled with all new coolant, and burped the system. I then took it on a 65 mile drive with no issues, it ran nice and cool the whole time with ac on, when I got to where I was going I let it cool down for a while and checked the coolant level again and still full. Well all that was yesterday, and now I check the coolant this morning and it is low again, I don't know where it is going, there is no coolant on the ground under it, I don't see any getting in the oil at all, I cant seem to tell where it is going.

It looks like the water pump and thermostat were recently replaced, and I see no signs of leaking around there, where do you recommend I look?

Thanks

 

I know you said your not seeing any on the ground, but these trucks are notorius for LIM gasket leaks. Seems to be a random draw weather they will leak internally or externally. If its leaking internally it may not nessasarily be leaking in to the oil, rather leaking in to the intake ports and being burnt off, and at 125k miles Id guess that a LIM leak is the likely culprit.

Good luck and report back.

 

ok, what would be the best way to check if that is the problem or not? Do I just need to replace it and see if I am still losing coolant?

 

Did you check the radiator or overflow or both? Just asking cause my overflow had a crack in it and I was also loosing coolant there. As far as the intake gasket.... Look at the front of the intake where it meets the block and you can get your hand in the back and feel it. People also used carb cleaner or propane torch along the valve covers and if idle changes you have a leak. If you have an intake gasket leak its easy. There's tons of threads on here about it. I believe there's a DIY on it. Hope that helps you. . Lets us know what you find out

 

ok, I will definitely look a bit closer today after work, thanks for the input guys.
And yes I looked in both the tank and the radiator, I don't see any signs of a leak hitting the ground anywhere. but after about a 2.5 hour drive I was probably a half gallon or more low, between re-filling the tank and the radiator.

 

well it looks like it is the lower intake manifold gasket, and unfortunately i have to have a shop do it, as I am currently in the middle of moving and living in an rv. Thanks for the help guys in determining my issue, I should have it all fixed by the end of the week.

Thanks
swells87