Coolant leaks after the engine is turned off, why?? - Rennlist - Porsche Discussion Forums

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Coolant leaks after the engine is turned off, why??

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Old 07-17-2005, 10:16 PM
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Stan944
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Question Coolant leaks after the engine is turned off, why??

it started over a week ago. After I drive it for a while (e.g. 1/2 hour), when I turn it off, it leaks a large amount of coolant through the overflow tube in the reserve coolant tank. Each time it looses more coolant than you can see through the transparent ( well, maybe..) tank.
Anybody knows what the problem is? Could it be the cap of the tank, which seal is over it's prime?
I don't think it happens when I drive (i.e. the water pump runs), because the car doesn't overheat, and I never saw it when stopped, but still running the engine.
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Old 07-17-2005, 10:17 PM
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Replace your cap first and see if it keeps doing it.
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Old 07-17-2005, 11:23 PM
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Yup replace the cap with a new Porsche one.
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Old 07-18-2005, 01:02 AM
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Sounds like there is air getting into your coolant system, either the cap, like these knowledgable guys have stated or there is a pin hole leak in the expansion tank, radiator, or hoses.
Start by getting a new cap and bleeding the coolant system to purge all the air. If thing do not improve pressure test everything and hunt for a leak.
Cheers,
Jason
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Old 07-18-2005, 11:40 AM
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OK, I bought the cap this morning; didn't test it yet. It's a generic one, and hopefully it works.
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Old 07-18-2005, 03:43 PM
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Cool

your older ride takes the lower pressure cap.

if you have the 6 bladed fans, 1 stays on until the water temp drops to keep from busting hoses, like on the later cars.
i had the 6 bladers on the 84.

i thought i had a bad cap on my 84 and put one rated at 13 psi.
i had leaks i'd never seen before.

it's just building up too much pressure.

87951
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Old 07-18-2005, 10:44 PM
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I put the new cap, and the problem seems to be gone.


Originally Posted by bearone
your older ride takes the lower pressure cap.

i thought i had a bad cap on my 84 and put one rated at 13 psi.
i had leaks i'd never seen before.

it's just building up too much pressure.

87951
Well, the new cap is labelled 13lbs/90kPa. According to the above it's wrong.
The original is labelled 100 (no unit, so I presume 100kPa), which is even higher, meaning my new cap should be OK. I don't have leaks as of now, but will get the correct cap if required.

Could someone confirm the pressure of the cap on 1983 944?
Thanks.
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Old 07-19-2005, 02:48 AM
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Cool

the original or the cap that happened to be in place.

when i put the old cap back on i had no leaks.

is it still leaking?

checker shows a 13# for the 84 and a 16# for the 87.

87951

Last edited by bearone; 07-19-2005 at 03:05 AM.
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Old 07-19-2005, 03:30 AM
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I ran into a very similar problem about 2 days ago.... The coolant seems to be leaking from the drivers side, and only after the car has been shut off for some time.

It seems whenever something goes funny with my car... someone else is experiencing the same problem.


Will a radiator cap from autozone/advance auto work? or should i go for the "factory" cap?

And can a faulty radiator cap lead to overpressurization in the cooling system?
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Old 07-19-2005, 03:42 AM
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cap's a cap unless you feel a need to spend more $$$$.

not faulty but using one that has a higher rating than the system needs.

if the cap isn't sealing it's leaking.

the 951 has a 16# with a release lever and isn't german.

87951
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Old 07-19-2005, 10:35 AM
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Originally Posted by bearone
the original or the cap that happened to be in place.

when i put the old cap back on i had no leaks.

is it still leaking?

checker shows a 13# for the 84 and a 16# for the 87.

87951
Sounds like my 13psi cap is what I need for 1983. Thanks.
The annoying leak is gone.
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