Sludge in the oil cap - Experiences pls

[Zed414]

Hi Guys

Would you guys be able to advise on your experiences with your Z4's please

Is it normal to have oil/water sludge in the oil cap over winter?

Bought a 2006 Z4 2.5 in Sep last year, it had done 95k, no history with the car. I've only used it once/twice a week over the winter short journey, 10 mile max trips and I had cleaned the car so I know the cap was clear before.

It's due an oil change in 1k (which I was planning to do this month before I start using the car more regularly for summer) and I have the normal rocker cover leaking onto the manifold which is how I discovered this, noticed an oil burning smell and was checking the engine area, so will get that done too.

Its not overheating, the water is not boiling over when hot, fans are cutting in/out ok, dipstick is clear

I will get a head gasket check just to be certain, but interested if this is a normal thing

I've cleaned the cap now and will use the car a bit more and keep checking it over the next week.

Thanks

 

[caius]

Given you've been doing infrequent short journeys in it I wouldn't be worried about that. I've seen similar on both a M52 and M54 engine, and neither had a blown head gasket. I'd suggest taking it for a longer run, half hour or so and get it nice and warm. Burn off some moisture

 

[Rockhopper]

Yes totally normal in the cold weather, i can even get actual water dripping from mine sometimes. Even very long runs wont make it go away I've found though.

 

[Consumer974]

Just to chime in, my cap was clear of any sign of mayo when I bought the car back in October, since then I’ve been doing almost exclusively short commutes (about 7 miles each way) and it gradually appeared and became mire and more gunked up. After a rare 2 hour A-road jaunt, I noticed it was totally mayo free again… until I got back into the short commutes :rofl:

 

[skmattwell]

If It doesn't clear up once the weather gets warmer and you experience any misfiring I'd look into replacing your CCV valve system.

 

[Joez4]

I also get this in winter, a good 30 mile plus trip usually clears it up.

After replacing my ccv system I noticed a significant reduction of mayo build up from short trips but still get some.

When I replaced my ccv I opened it up and found it was gunked up pretty bad it looked like the original valve 20 years old and done over 100,000 miles defo worth replacing it as it also lowered my engines oil consumption.

 

[Zed414]

Brilliant thank you all for your expertise, much appreciated

 

[Zedebee]

A little mayo under the cap in cold weather is not unusual, but it could be a sign of a clogged up CCV which won’t fix itself. You could try detaching the CCV hose at the front of the engine and see whether it’s clear, but beware, it will have become very brittle and may (probably will) break. If it is full of gunk, you will need the replace the whole CCV anyway. If not, you just need to replace the pipe which is inexpensive.