ok, can anyone show or describe to me what the stock radiator cap looks like? I run evans and want to convert to zero pressure. I have heard that all you need to do is remove the rubber seal from the radiator cap (pineapple). I have a pettit AST. It has a huge cap with spring and two seals. There is a red locking lever on the cap. The cover says 13 lbs. My radiator filler cap says only "filler cap" and then has some japanese writing. There was only one gasket on this cap and no spring. The pettit AST was put on before I bought the car, so I have no idea what it looked like prior. It looks like the only pressure cap is on the AST. My dumb *** removed the gasket from the filler cap. Now I am afraid that the system will spew coolant from the now gasketless filler cap because of the high pressure AST cap. Am I ok, or have I just f***ed up bigtime? How do I fix it?

 

You will spew coolant through the filler neck now. You should have removed the seal attached to the spring on the pressure cap which is the one on the AST. Removing that seal will allow coolant to reach the overflow tank line before pressure has built up.
Pretty much you need to find a replacement filler neck cap, I believe you can only get them at the dealer for about $20.

 

I did the same thing the first time. Coolant everywhere. I got the seal back in with no problem however.

The way to do it is how Tom93R1 stated.

 

Question: If I remove the lower seal, thus converting to zero pressure, and I replace the gasket on the filler cap, would I be ok then?

 

Question 2: Glad that coolant will reach the overflow but, will it return without the high pressure cap? I guess that it will since many people do this, but it makes me a bit nervous.

 

1) yes you will be ok

2) It will return unless you have a coolant leak somewhere. When the coolant heats up it will expand and overflow to the tank. When it cools off it will contract and create a vaccuum inside the system, pulling coolant back through the overflow line. If you have a coolant leak the vaccuum may suck air in through that leak instead of the overflow line.

 

cool, thanks for the replies. There is a small split in the gasket on the filler neck, but it is near the inside and so I think I will be ok. Gotta love live tech chat on the forum. Thanks Guys!