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[Jaf]

Hi guys, sorry if this is completely obvious but just want to check. My car is staying with a friend (until I decided to sell her or bring her to Spain) and he says the expansion tank dimple (technical term? it's a dip that is about thumb sized) has water in it. He's not been driving her much and says there's no noticeable water loss. So should she have water in there? What's it for?

Thanks! Jaf.
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1978 924na

[Blas]

If your refering to the indent on the top of the tank. I believe it is part of the molding process and I have seen a liquid build-up there. Mine had the same problem, and over time you loose antifreeze and can get an air pocket if you loose too much. I tried everything to seal it, but nothing lasted long due to the expansion of the tank when it gets hot. You might first check that the filler cap is seated properly, and there is no leak in the hoses in the area. The dimple is where liquid will collect (low spot)...I finally replaced my tank when I flushed my cooling system...

[Jaf]

Thanks for your reply. Do you think that as the dimple is caused by the molding process it's not actually there for a reason? Haven't seen any other tanks with such a thing though. Never mind! Looks like I'll need a new tank at some point providing that is the actual cause of the water and not as you've said cap or pipe.

Thanks again. Jaf
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1978 924na

[Blas]

I thought it might also prevent the tank from colapsing under a vacuum, but upon further examination, it looked like a forming injection point...

[Joes924Racer]

& a fail point kind of . I used to seal it up
you know fill it to the brim I mean /I coated the bottem
1/3 with the stuff.I have or had 2 cracked ones stuck in the
pile its a fail point from what I dont know. See I went thru
a few I got used .. ............... . .. ... spaced dots say
the last 6 dots I typed if you look at them do they remind you
of the american space shuttle Discovery breaking up
appearing as white flashes of light on a light blue black ground. lol
high temp silicone anyone. though its not recommended she can
drive it & if theres no - problems at all she can driver it as usual.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

[Mike924]

Hi Jaf,

is it definitely coolant water that's collected in the dimple?
If so, it could just be a bit that's leaked past your radiator cap seal. A new cap should cure this (<£5 from Halfords). As there's no obvious loss of coolant level, it's definitely not serious.

Has 'Tiddles' been parked outside? It could simply be rain water running off the bonnet, over the header tank and collecting in the dimple.
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1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

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