M54 Condensation on oil filler cap.

[Gjay]

I have a 2004 M54 motor in an early z3. It was running ok in a writeoff E46 and has done 175,000km ( 110,000 miles) . From time to time , since 2017, I have noticed water condensation on the oil filler cap. No sludge or oil discolouration and water level remains ok.

I was thinking about a head gasket leak and maybe checking the head bolt torques, (retension???) but dont want to make matters worse at this stage if possible.

Then I came across this Utube where Nathan claims water vapour coming in through the CCV vent is normal, he says "its usually worse than this". Is this correct?

https://www.youtube.com/watch?v=MG5XnVHVm94

Not sure about good old Nathan's experience because he seems to have replaced head bolts and doesnt seem to realise they are 'torque to yeild' bolts.

Any advice re moisture and/or the re-torque.
Thanks

[02Pilot]

The M54 CCV system is...problematic. My suggestion, before you do anything else, is to read this: https://www.bimmerforums.com/forum/s...CV-replacement

It deals more with oil consumption than with moisture accumulation, but a byproduct of the mod described therein is the total elimination of moisture from the CCV passages and crankcase. If you have questions about anything in there, just ask. I doubt you have any real problem - moisture is pretty typical to some extent in all engines - but if you want to make sure whatever's in there gets burned off, the mod will help with that.

[randy72877]

It's normal for there to be some yellow gunk or mayo on the cap. Cold temps and short trips make it worse. All engines produce water. It's a byproduct of the combustion process. Don't worry about it or mess with the head bolts.

Sent from my S61 using Tapatalk

[Gjay]

Thanks Pilot and Randy. I note that you both assert that moisture is present. Perhaps this is cold climate related. I am in Australia and generally we dont have temp extremes like North America and Europe. Not new to the repair game and if I ever see "yellow gunk or mayo on the cap" I know the head gasket is buggered or head is cracked. But given as you say the CCV system is problematic I will take it as read that the moisture is normal.... I hope.

This probably why I changed the CCV when I swapped the motor.
I too have the smoke after a down hill run and high oil consumption. Assumed it was stem seals, hmmm... re-read your link and go back to the drawing board. Cheers Guys.

[02Pilot]

With the other symptoms, you have nothing to lose by doing the mod. Read carefully, as there are a few things to look at beyond just adding the vacuum hose.

[MarcoZandrini]

Take the car on a 20+mile trip at highway+ speeds on a weekly basis. This will burn off any condensation in the engine. Short trips (less than 10 miles of continuous driving) don’t get the engine up to full operating temperature.

[jclausen]

The shorter the drive the less chance the engine has to burn off condensation, which is a byproduct of combustion, remember seeing water out the tail pipe on cold starts? Oil mixes with the condensation and produces an emulsion like salad dressing.

[Gjay]

The M54 CCV system is...problematic. My suggestion, before you do anything else, is to read this: https://www.bimmerforums.com/forum/s...CV-replacement

.... but if you want to make sure whatever's in there gets burned off, the mod will help with that.

Re thinking the set up this end. Now wish I hadnt changed the CCV during the 1997 to 2004 engine transplant, just so I can eliminate that unit. Brain is moving back to vacuum and possible air leaks so quite possible CCV is related.
Have chased leaks previously because when the engine is warm it runs as sweet as....heaps of power; but it will not idle when first started cold. Fault seems typical of comments about bad vanos seals, however that was not a problem when it was in the donor 330i.

[02Pilot]

If you've got a vacuum leak you'll have to address that first. Smoke test, seal crankcase, then mod. The problem with the M54 CCV is that - even when it works as designed - it pulls very little air out of the crankcase. Add a vacuum leak, short drives, and imperfect ring/valve sealing, and you've got a recipe for problems. The mod radically increases the flow through the CCV, which has lots of positive effects, but the crankcase must be properly sealed for it to do its job.

[MarcoZandrini]

The M54 CCV was designed by an engineer who’d been fired by Audi. /s

[Gjay]

If you've got a vacuum leak you'll have to address that first. Smoke test, seal crankcase, then mod. The problem with the M54 CCV is that - even when it works as designed - it pulls very little air out of the crankcase. Add a vacuum leak, short drives, and imperfect ring/valve sealing, and you've got a recipe for problems. The mod radically increases the flow through the CCV, which has lots of positive effects, but the crankcase must be properly sealed for it to do its job.

Thanks mate. I will put all options on the table. Have often used the smoke test and even a squirt of propane is a good indicator around intakes. Spent yesterday reading up on this Bimmer CCV so it remains a prime suspect, Cheers .