White/Yellow Gunk under Oil Filler Cap

tosborne

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E320 CDI Jan'09
Morning all,

I was looking at my engine just now and when I opened up the oil filler cap, I noticed that there was a small amount of pale coloured gunk under the filler cap - not a pretty sight!

I always thought that this meant a blown head-gasket, allowing coolant into the oil and the oil/water combination causing the "mayonnaise", but I can't see any trace of oil at all in the coolant tank, and the car is performing beautifully! :D

Only thing is, I have just changed jobs and so rather than an 160 mile ride from Milton Keynes to Epsom and back each day, my new job is a mere 1.6 miles away from home - big luxury but car temperature never gets above 60C, could it be this causing the mayo, the engine not getting to temperature, and the water produced from burning petrol now not having time to evaporate??
 

Brian WH

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You will not see oil in the coolant mate, as if the head gasket had blown the water would be getting into the oil, not the other way around.

In this cold weather it is possible on short runs to get "condensation" in the rocker box cover where the filler is. Lets hope that is all it is.

Look on the dipstick when the engine is hot and cold, if there is just "Oil", then you have nothing to worry about mate, if there is the same discolouration then you need to get it sorted.

Hope this helps.
 

Sp!ke

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I think it more likely that this is caused by your short trips. There is nothing worse for the car than doing regular short trips like this.

Best thing would be to leave the car at home and get your bicycle out for the 1.6 miles :p
 

Mark300SL

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Originally posted by Brian WH


You will not see oil in the coolant mate, as if the head gasket had blown the water would be getting into the oil, not the other way around.

Brian - thats not technically correct :)

If you get mixing of the water and oil - there has to be a breach of the headgaskets integrity - this means that the contamination could go either way depending on the pressures involved.


Originally posted by Brian WH

In this cold weather it is possible on short runs to get "condensation" in the rocker box cover where the filler is. Lets hope that is all it is.


This however is totally correct - and is also the most likely culprit :D

The engine is not getting hot enough to evaporate the condensation - so it mixes with trace oil in the head and forms light caramel coloured deposits


Mark
 

Brian WH

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Oooooh Only 90% right then teacher.

Sorry to mislead you slightly, but in my experience the water pressure "Usually wins", if it doesn't the gasket is totally Kna##ered.
 
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tosborne

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E320 CDI Jan'09
Thanks for all the replies guys! I've now cleaned off the gunk and I just need to try taking her for a nice long run now to see if all the short journeys are the problem; Sp!ike you're right - should use the bike :)
 

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