Swaie

Okay, I just got my vette back from the tranny shop, and drove to town tranny did awesome! But now I pull up to the gas station and see steam coming from the coolant surge tank. It's leaking from the cap. Does this mean that have a bad head gasket? I'm going to change the cap first and go from there, but what else could it be. I noticed that it bubbles after I turn the car off and it heat soaks...any ideas?

BigGun

What is the water temp reading?

SteveDoten

Coolant tanks often fail, but it's a leak near the aft hose attachment, the plastic cracks or the hose will get soft/punky

what else was done to the car?

Fans turn on at correct temp?
Fan turn on changed in tune?
Tstat is opening correctly?
correct Dexcool mixture?

OEM cap PSI is 15......changed to 16 in 2003/4?? if your coolant is 'bubbling' kinda sounds like a straight water mix??

Another note: the radiators in C5's sometimes clog up near the 'steam vents', small lines on RHS of rad.

lot's of variables, make a list, go after the easy kills

Swaie

I changed the cap, but the temps get as high as 235!!! I'm going to clean the radiator today, but I changed the cap with a cheap one from Oreilly Autoparts. It seemed to stop the leaking. Ihave the Dex 50/50 mix. I will check the steam ports today also.

Jesse Asis

Make sure you didn't over fill the over flow tank, it could as simple as that.. Use a flashlight and shine it on the front corner of the OVER FLOW tank, it will be molded in the white plastic where your coolent level should be... If you over flow and it gets hot, you make have no room in the over flow for it to expand, thus leaking from the cap. This happened to me when I replaced my water pump, I over filled it waiting for the air burp that never came... Also purchase a ANTI-FREEZE TESTER, they are a few bucks, it can test the coolents ability for protection level... Good Luck.

jlbsam

also, check the nipple that extends out from the front of the tank, a rubber hose comes of that. the nipple could be cracked. that was my problem, a new expansion tank solved the coolant leak. Zip Corvette had the best price on the tank

lionelhutz

Last I looked, there was a hose at the back top and 2 underneath the tank hooked to a T coming out of the bottom. You are correct though, the one at the top back in the black is prone to develop cracks and leak.

Jesse Asis

Yes true, the top inlet is easy to bend and break the plastic nipple. Inside is a copper rod that extends into the over flow tank. Mine started leaking from that and the whole tank has to be repalced, can't fix.. Try not to put any pressure on it after installing the new tank for it cracks there most of the time.

cache1

So was the new cap the permanent fix Swaie? I'm having the same symptom on my 1990 c4. I have a post over on the C4 side of the forum and would be very interested to hear if you are done done. I replaced the cap on my car but still have leaking.