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Head Gasket?

Toby Low

6 Sep 2004
I have just topped up the oil on my 1986 3.2 - I had let it get a bit low - and I noticed some rather worrying yellow frothy stuff around the oil filler cap. I have a nasty feeling that this could be a sign that the head gasket is about to go - but I guess it could also just be caused by condensation around the oil filler. Any ideas?


Migration info. Legacy thread was 26166
3.2 Carrera is air cooled, doesn't have a head gasket !!

The emulsion is caused by condensation, worse in winter and if you do lots of short journeys.

Don't worry about it.

Migration info. Legacy thread was 26224
Thanks Matt - I feel a bit of an idiot now!! Can you explain further - isn't the gasket just the piece that goes between the cylinder head and the engine block. Sureley any car - air or water cooled has one of these - this is what I am worried has broken.


Migration info. Legacy thread was 26251
The white emulsion under the cap is very common on these cars. Take it for a nice long blast and get the oil temp up. This should get rid of any condensation and stop the oil tank resembling a mayonnaise factory.

These cars don't have head gaskets just a sealing ring. Think of the ring round the combustion chamber holes on a water-cooled head gasket

On a water cooled car the head bolts onto the block and the water passages in the head gasket allow the entire cylinder and combustion chamber to be surrounded by water.

The other holes in the gasket allow oil to drain back down from the head and into the sump.

Instead of being surrounded by a jacket of water, the 911's cylinders and heads are cooled by air being blown down onto and across it by the engine fan. The cylinders are finned like a motorbike engine to maximise surface area. Stick your head up under your car and you will see 3 tubes running from the heads to the block - these let the oil drain back down to the sump so no need for a gasket there either.

Technically speaking these cars don't have a block. It's a case. The cylinders attatch to the case, and the heads go onto the cylinders. Oh, and the case splits in two with the crankshaft sandwiched in between the two halfs.

Different huh?

Migration info. Legacy thread was 26292
As 911mot says, the 911 engine doesn't have an engine block just a crankcase and individual finned (for cooling) cylinders that fit into the cylinder heads.

Even if one of the cylinders was somehow leaking where it joined the cylinder head, this wouldn't cause white/yellow emulsion to form, because no water would be able to get into the oil. The cylinder would have low compression and hence the engine less power.

On a normal water cooled engine if the head gasket fails then water gets into the oil, forming the emulsion. The fact this can't happen is one of the big advantages of an air cooled engine, so stop worrying !!

Migration info. Legacy thread was 26311
Thanks for this chaps - I am now wised up! Various bikers in my office had tried to explain this to me - but not nearly as well as both of you.


Migration info. Legacy thread was 26315

I have a 996 which is displaying yellow mayo lokking stuff is it same as above or should I worry

Migration info. Legacy thread was 26825
give the old 3.2 a engine oil flush and a couple of changes it should be ok then

Migration info. Legacy thread was 26832
spoke to OPC apparently as mentioned above it is common in cars making regular short trips in winter and oil not heating up, it will be dealt with at next service. This is a relief though quote for 24k service at £625 seems a bit steep.

Migration info. Legacy thread was 26904
That does seem a little steep.

I just had the 48month/48,000 miles service done, with brake fluid change and main belt for little more.

I would suggest you ring around a few OPC's - I've found some significant differencies in service pricing.

Good luck

Migration info. Legacy thread was 26913

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