OK, so last week I posted about my plastic coolant resevoir tank cracking and leaking coolant. I replaced the tank and now I may be screwed! Everything was fine until a few days after the replacement and BAM! There it is again, the dreaded sweet smell of coolant. I look down the neck of the tank, and there right to the side of the neck is a very small hole with what looks like a rubber washer around it. Coolant is slowly spilling out of this tiny hole. I called Pettit Racing and talked to one of their rotary mechanics, and he said it could be a few things. First, that hole is a venting hole to let hot air escape the tank. If coolant is surging out of that hole either I have blown a side seal, blown a coolant O-ring, or the cap on my aluminum AST isn't holding pressure. He said if I had blown a side seal than compression is escaping the engine into the coolant forcing it through the vent hole. If I blew an O-ring, I figure that I would be burning white smoke like mad, which I'm not. The other odd thing about this, is that it is totally random. Matter of fact is hasn't puked any coolant out in about 4 days. I have since then though, taken off and put back on the cap of the AST to make sure it was on correctly. Hopefully that was the only problem. If anyone has any info on this type of problem, or what the symptoms of a blown side seal or coolant O-ring is then please help! Thanks

 

I had the same problem with my car. I also had the Pettit AST however I don't remember a breathing hole of any sort? I got really pissed off and yanked the engine. When I took it apart I sure enough my O-rings were fried! I never once saw white smoke coming out of my engine. If the coolant is spewing out then that would be a good indication of something worng with your engine. Is it overheating? or any other problems then just the coolant coming out?

 

Nope, never overheated once. The "Add Coolant" light came on once because it narfed up a lot of coolant, but I added some in, the light went away and hasn't come back on since. But since I screwed around with the AST cap it has stopped so far, that's why I'm so confused. On the plastic resevoir tank on the passenger side, if you look down the filler neck right at the base where it meets the tank, about a centimeter away is the hole with the rubber washer. Both my old dead tank, and the new one that I picked up have it.