I'm down to the final stages of getting my road race '96 TA ready for it's first race weekend next weekend.

One of the issue I have is when it would get to about 210* indicated, it would begin filling the expansion tank with coolant and continue to do so till it cooled.

At first, I thought I had put too much water in the system, but as much water as was puking out, there was no way the system needed that much expansion room.

I decided that "performance" Moroso radiator cap i got from Jegs (19-21psi) was a fluke and was lifting prematurely.

I went to O-Reilly's and bought a Stant 18psi cap. It did the same thing! Now, I am getting worried that there might be something else wrong.

For grins, I rob the cap off of my '98 TA and run the car to 225* without any issue.

So, I take the Motorso cap, the Stant from O'Reilly's, my used cap and a new one I pickup at the dealership and head over to a radiator shop to get them all tested ...

Moroso - lifted at 6psi, held at 4
Stant - lifted at 4psi, held at 3
Used - lifted at 20psi and held at 17
New GM - lifted at 20psi and held at 17

The GM caps are TVS brand and the guy at the radiator shop said that it was not uncommon for new caps these days, to be junk ...

 

Hmm.. I just bought a new 18psi radiator cap from Autozone and I was pissing coolant too.. I didn't really think I overfilled it that much.. I wonder if I'm experiencing the same thing you were...

I'm going to take it out today and see if it keeps doing it..

How can you tell when you've got it back to the "right level"???