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can't find the number for this gasket near the thermostat


PCGB Member
I have a water leak where #7 meets the thermostat but I can't see the gasket on the drawing? Confused!


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The O ring often leaks. I have several times resorted to flatting off the flange and using a smear of Hylomar.
Someone may have made their own but there definitely isn’t a factory one there. I even removed this to fit the proper block-off one at the end of last year when I moved from a water cooled turbo - I’ve checked the receipt, one elbow and one O-ring (I did use a smear of hylomar on the mating face too as Graham and many others do).
I agree with all comments -a new water pump on my Wife's 1986 924S came with the Turbo nylon elbow outlet hole which seals with the O ring -I made sure the pump surface was flat & also used a little Hylomar.
my similar but year later 924S track car (road useable) had a persistent small weep from the elbow joint which required regular header tank top up (I could never find the leak after track use) .Eventually traced to this joint & found the nylon elbow had got distorted such that the O ring wasn't seating sufficient to seal properly.
A little file work plus wet & dry paper on a glass surface resolved the problem plus a new O ring.
Yes Colin. The flange around the O ring and metal sleeve is not flat, so dressed it back with wet and dry like you. Heard my late father's words from the past (high pressure steam at GWR Swindon)..."you'll never get that to seal"!!

When overflowing into the bottle it's under pressure?
Thanks team, I cleaned things up, gave the mating surfaces a little sanding, replaced the O ring and used a wee smear of gasket sealant and all seams well - whatever O ring was there before had hardened into plastic, seemed like a bit of a bodge to me. Like Vitesse I had been topping up my header tank once in a while and for the life of me couldn't work out where the leak was coming from - until my power steering had the odd stutter and realised there were drops of water on the belt.

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