924Board.org

[BC77-924]

I have searched the archives about coolant leaking from the expansion tank after shut down. The consensus seems to be that the Rad Cap needs replacing. My original one was rated fro 15 psi. I picked one up at Napa today and that one is rated at 13 psi....I have not tried it yet. Would it be better to stick with OEM????

Thanks

D
_________________
Silver/Grey 77.5

[924 driver]

I had good pressure and all but coolant kept spewing
changed the cap and the problem went away for $9 bucks.
plain old replacement cap works fine.
_________________
Peter
1979 924 na

[Mike924]

I thought 13 psi was the OEM rating...

But really, I don't think there's a lot of difference. If the tank's going to boil over at 13 psi, it'll probably only be another mile before it boils over at 15 psi.
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1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[924RACR]

Agreed... my 931 is currently boiling over if I shut it down with the temp over about halfway. I was thinking about swapping on a new cap, might have to re-bleed the system too... but I just checked this AM after I got to work - and one of the fans isn't running. Makes sense, as the car wouldn't cool quickly when the fans did come on (car has functioning AC and I use it regularly).
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[billmay34]

i am interested the knowledge that others have on the follow problem....

After a top end rebuild of our 924 (77) we were delighed that the engine purred back to life. however the machine was running mightly warm, nay, hot. to the point that the overflow tank breached a small hole at the dimpled seal to the left of the cap.
we examined and decided that replacing the thermostat and the cap would solve the probelm. we epoxyed the tank and all seemed swell.
further test driving brought a repeat of the problem. the expoxy fix did not hold and the overflow tank now is damaged beyond furhter repairs.
what say you other smart, talented members? should i suspect the radiator? does anyone have a replacement overflow tank?
can anyone discuss with me the process to purge the system at startup?
any and all advise and thoughts are really appreciated!
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Bill May
Seattle, WA
1991 MB 300E - 202,000 Miles
1977 Porsche 924 Martini - 85,000 Miles, Purple.

[Mike924]

OK, so your expansion tank had a hole.

Was this hole there before you rebuilt the head? Or do you think the hole was blown by over-pressure in the system? If so, why didn't the pressure cap relieve the pressure?

There may not be anything wrong with the system - 924s run notoriously hot. Get hold of a used replacement expansion tank (I've seen plenty on E-bay in the UK) and a new cap and try again. If the cap blows, you've got a pressure/overheat problem which will need to be investigated separately.
_________________
1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org