LuigiVampa

I've been to the track a few times this season for HPDE. Coolant level is fine before the run.

Normal temperatures during the run.

I take a cool down lap and let the car idle for about 30 seconds to make sure the turbo gets cooled.

A minute or so after I shut down coolant starts pouring out of the overflow tube. Brand new water pump and thermostat. Car is a 1987 951.

Anyone have any ideas what could be causing this? Thanks.

RajDatta

Head gasket is done.

LuigiVampa

No coolant in the oil. No white smoke in the exhaust. Why do you think the head gasket is done?

chrenan

Have you tried replacing the cap on the expansions tank? May as well try all the cheap easy stuff before jumping to the head gasket. If that doesn't work a leak down test will tell you more.

Jfrahm

If your cooling system cap is bad, it will behave as you describe. A terrifying stream of coolant from the overflow after shutdown.

LuigiVampa

Thanks for the input. When I replaced the water pump and thermostat I did also replace the cap on the expansion tank. The problems occurred after this so hopefully it is the cap. Thanks everyone for the input!

Jeff N.

You can try the cooling overflow catch can trick - put a water bottle on the overflow hose and drive it for a session. If you have water in the bottle, it's likely you have a pressure leak from the cylinders pushing the water out past the cap.

LuigiVampa

I don't have a problem when the car is driving - it doesn't leak at all. About 30 seconds after I stop, and only after a really spirited run, fluid starts leaking out of the overflow. It generally does not happen after I am driving around town.

I'm hoping it is merely the cap. Any reason why it should be anything worse based on the above explanation?

Ronin-951

Happens to mine also if I fill above the Min Mark, two years now without losing a drop.

LuigiVampa

Because of the past problem I was very conscious of the amount of coolant in the expansion tank and I was right at the minimum mark.

Two new caps on order. My previous cap, just a couple of months old, was a Behr brand cap from pelican. I'm going to see if I kept my old cap and switch it back.

Need to find a place to drive hard enough to get the car warm enough to replicate the problem. I don;t want it to be a head gasket - that would suck.

RajDatta

I had a similar problem with my car years back, which s why I know. I hope its something different, but your symptoms are exactly what I had.

mtnman82

Went thru this recently and wound up replacing my head gasket. All is good now...

dmcampbell

Same symptoms for me, it was only a bad new cap!

LuigiVampa

I like your comparison better than the other ones!

lart951

same issues for me and it was a cracked cylinder wall,