Hey guys, about 17k miles ago, I had a coolant flush done. About 2 months ago, I was checking the fluid and noticed that the radiator was about a half gallon low. I filled it up....and the overflow tank. Since then, I've had to fill the radiator and overflow tank every week, BUT I HAVE NO LEAKS. Does this sound more like a bad radiator cap or bad head gasket? I'm going on a road trip tomorrow and need to get resolved (if I can) soon. Please help. Thanks.

Car has 142k on it, before the coolant flush I never lost one drop of fluid from my car...and now this.....

 

Is there anything else that would cause a cooling system to lose fluid besides evaporation through the radiator cap, leaking, or consumption in the combustion chambers?

 

I've had a couple of different cars that had tiny holes in the hoses that would only leak under pressure so whenever I checked under the car for coolant leaks there were none, but the coolant mysteriously dissappeared. Had a waterpump on a v-6 bird do the same thing, it only leaked while running up to temp and pressure.

Moral of the story; take it for a drive long enough to warm it up good, when you get home, pop the hood with it still running and you might catch the culprit in the act.

 

Do what Al said to do and don't forget to check the 4 coolant cross over blocks at the front and rear corners of the heads . You could also have someone pressure test the coolant system to try and find the leak as well .

 

I've done that several times already. I mysteriously used a gallon of coolant today on an 800 mile road trip. Car ran strong, but used coolant. Tomorrow I will have the system pressure tested and the radiator cap tested. If they both come up good, I will be at a loss as to what's wrong.

 

Thanks, I will do that....

 

Well, I found the problem.....
I had the car on the lift this morning, and the water pump gasket is leaking from underneath. With 142k on the car, I'm just going to replace the pump as well. Just one quick question.....are the LS1 waterpumps as straight forward as the LT1 waterpumps?
Also, my radiator cap isn't holding ANY pressure!

 

Are there any tips or tricks to bleeding the system on an LS1?

 

Water pump is easy and straight forward.
To bleed just raise the front of the vehicle, pull the little coolant hose off of the front crossover tube, fill 'till some coolant comes out of that crossover tube.

 

I replaced the w/p last night...very easy. Though I got A LOT of air out of the system, I did not bleed it the way you explained. I will do that tonight to see if there is any more air in the system. Thanks for the advice.