Tom M'Guinn

Try driving a long way but without any boost -- fully warm it up over 20 - 30 miles or so -- then see if it spits up. If no overflow that way, then go out again and drive it hard on boost and see if it then spits up. If it only overflows after boosting, start saving for head gaskets...

ilikemy944

I had this issue once as well, after auto-x runs it would pee coolant. Bad cap for me.

Jeff N.

Nothing like a problem that ranges from a $15 cap to a new engine.

ilikemy944

But those are the most fun, and after you replace the entire engine, you will find that it was the $15 part...

kent426

So you could also have air in the system from when you refilled it if it was not bled properly. Also according to Lindsey Racing, the heads have poor cooling on cylinder 4 which may be overheating?

überschnell

Try popping the cap off and smelling the coolant. If it is a head sealing issue, it generally means the head is lifting and you're leaking combustion pressure into the cooling system...I have experienced this, and the coolant will smell terrible if that's the problem.

Odds are pretty good that it's just the cap or maybe even an air pocket, but it could definitely be something more sinister.

Ronin-951

Good point on smelling the Coolant, Part House's have a chemical that can test for exhaust Gases in the Coolant which could save you some hopefully unnecessary worry and work.

blodstrupmoen

I would assume coolant would go into the engine when stopping after at H/G disaster .

Willard Bridgham 3

You can also get a higher pressure cap from Racer's supply Warehouse. That did it for me.

LuigiVampa

Do you know temperature it opens at?

I ordered a couple of new caps and they are the same Behr one which I believe is 150 degrees celsius. Hope I just got a faulty one.

LuigiVampa

New cap installed and I took it for a spirited run in 85 degree heat. No coolant issue - cap did the trick! Thanks for all the input. Didn't really want to do a head gasket.