I just want some clarification on this before I buy a new overflow tank..... It seems like if you turn the car off, wait a few min and the coolant leeks from the overflow tank that it is caused by a cracked tank.
Well here is my question... I can see where the water is comming from and it is not a crack. It is from a rubber grommet (looks like a vent hole) in the top of the overflow tank. Is this still caused by a crack? Or could this be something more serious?

I just took my AST out last week because it soiled itself! When I took out the AST I did the normal mod and capped the old fitting on top and on the radiator. Then I ran the overflow hose to the new cap (86 RX7). No leaks from there. I thought that was my problem.... but it is still leaking when I turn off the car.

Thanks in advance!!!

 

Yep there are actualy two gromets on top of the overflow tank, one of them is the vent, the other one has the hose to the AST hooked to it. For some reason your coolant is going into the tank and not returning to the system. It will continue to overflow untill you get the fluid in the resivoir down to it's normal level. You also need to find out why it won't go from the resivoir to the coolant system when it cools down. Jack

 

When this happen to me I could not find any crack. I would park the car, then 2 to 3 minutes later alot would drain out. I can see the coolant leaking down the side of the tank. I still have not checked to see where the crack was. I can tell you that a new tank fixed my problem.

David

 

Im having the same problem!!! :/ i've checked my resevoir tank and no cracks... should i flush the cooling system? or will i need a new radioator??

 

How do you know there is no cracks? They will not be visible to your eye. It will leak when the fluid is hot, thats why it leaks after you park the car. After its been sitting you can fill the tank up and it will not leak.

As I said, I replaced mine and it fixed it. One of the things I did for a temporary solution was some gasket spray. I went to the auto parts store and got this spray, it sprays on red and is designed to seal gaskets. This stuff will actually work for a few days at a time. Take off your container and spray this stuff all around it and see if that helps. If it helps I would get a new container. If it doesn't help, then I don't know what your problem is.

 

How? hmmm.... i tried puting boild water in there and no leaks... silly huh?!? but i got to find out whether is leaking! the lil opening s the only place where the water seem to come out... so no leak rite? i'll try to get som gasket spray to be on the safe side...tanx for the info Zero...

 

Thanks everyone for all the assistance!!! I am new to the board and the advice really helps.

I got my system pressure tested today and no leaks. I think I will try the gasket spray trick!