Leaking Coolant Overflow Cap

[emmvette]

Originally Posted by bdw18_123

The '90 ZR-1 I used to have had this issue. But it wasn't coming out from under the actual cap.

There is a brass part that the cap locks onto, which is held on by the plastic neck of the tank. On mine, the brass part could be twisted back and forth, only being stopped by the overflow tube, indicating it wasn't fully sealed anymore. So fluid was leaking out from between where the brass part meets the plastic part.

So I just covered the whole seam all the way around (including around the overflow tube, but allowing for the hose to fit on still) with some JB Weld and that fixed the issue.


You must have a very early '90 Z if your overflow tank is white plastic. I've only seen the white plastic tanks on the prototype cars.

Hmmmm, My car isn't an early '90; its middle of the pack. However I can't vouch for how much is original on it. I have no brass piece like you mention above, just a white plastic tank with a thin walled (cheap) black plastic cap screwed onto it. Here are pics of my cap and the overflow tank.

You can see a little fluid on top of the tank, this is after a gentle drive. Looking at the cap, there is a good size hold about 7/16" dia in it that goes directly up and out to the outside. This is definitely where coolant is splashing out. I wonder if there is supposed to be some type of button or smaller insert so the hole isn't so big? Does this look right to you guys - is this what is on your overflow tank?