[Dormermike]

Evening

I replaced my ccv diaphragm about a year ago and i've realised that the front main seal is making a hamster/chipmunk noise when i come to a stop. Lots of info about this on the n54 and remedy is to replace the front main seal.

Anyone done that on an n53?

I shortened the ccv diaphragm spring as per bimmerprofs recommedation and im wondering if there is slightly too much vacuum in the crank case. I would have thought a shorter spring would close the diaphragm more easily leading to less vacuum though. It does seem slightly more vacuum at hot idle than I remember, but not excessive at all.

Any thoughts welcome. Might take the alu cap back off and stretch the spring to see if it fixes the issue.


Thanks

[Phil325i]

Could it be serpentine belt noise?

[0l0dom0l0]

It might be best to replace the entire valve cover and gasket with a genuine item, and see if it fixes the issue.

The crank seals blowing on the N54 are more likely to be related to boost in the crankcase, from blowby etc. It isn't something that I've heard of on the N53.

[Dormermike]

Same noise as here -> https://www.e90post.com/forums/showthread.php?t=629612

Pretty sure the CCV is working ok as there is very little vacuum at the oil filler cap.

[Dormermike]

Fixed. Turned out to be excess vacuum caused by the new diaphragm being too stiff, presumably slower to close and so not regulating crank pressure properly. I dont know if manifold vacuum is constantly "on" on the n53 or if its switched via a solenoid. Interesting that the vacuum leak via front seal only happened when braking, so i guess vacuum increases when braking somehow (engine over run perhaps).

Hope this helps someone one day!

[0l0dom0l0]

So how did you rectify? Replace the valve cover?

There is significant vacuum in the intake when the engine is on the over run, caused by the engine sucking air against a closed throttle plate, also known as engine braking.

[Dormermike]

Ahh haha sorry missed that bit.

No didnt replace who cover, just the diaphragm.

So as per bimmerprofs i had cut the diaphragm spring down, because the new diaphragm is much thicker and stiffer. I had used too much red RTV along the edges, I think, which made it even stiffer. I had considered not even using the spring it was that stiff.

In the end I bought a chinese kit off ebay which includes a black plastic cover, spring, and much more OE (thin) diaphragm. Installed it with minimal RTV whilst still ensuring a airtight/vacuum seal but didnt cut spring - works a treat.

Nothing wrong with the original alu cap and diaphragm, you do need to cut the spring with those, IMO, and go easy with the RTV.

The alu cap from vanosbmw also has little screws to help fix it down whereas my chinese one is held down by rtv alone. Now that I know the fix, I may redo it all again with the alu cap and the chinese diaphragm and spring, but for now, its fine. RTV is pretty strong when set and its not like its under pressure.