oil catch can

[b33mer 11]

What do you guys think? a good idea or waste of time? In theory should help with the carbon build up problem on direct injection engines and cant do any harm right?

[wrs 120]

I have a M50 hybrid engine with M50/M52/M54 bits on it. When I first installed the engine I just used a catch can because it was the easiest solution at the time. There was always an oily smell and it leaked oil on the drive.

Recently I fitted the M52 CCV system so I now have a mild vacuum. I've made the cyclone/pressure regulator really easy to access so it can be replaced when it fails.

The difference is amazing - no more oily smell and no oil leaks on the drive anymore.

With a catch can the crankcase will be pressurized in order to push the gasses out. This tends to push oil out anywhere it can. If you have your windows down you'll also often get a strong whiff of crankcase gases as you pull up to a stop and sometimes under deceleration at low speeds.

Maybe a better option is to keep the existing CCV but add additional oil separation, maybe another cyclonic separator from a V8?

Edited June 27, 2020 by wrs

[zero 1162]

Add a catch can or cyclone separator, and keep the ccv like Warren recommends. 

 

And its the internals of the catchcan that are important and not all catchcans are created equally.

[wrs 120]

Yep, should have mentioned that - good call.

Most catch cans have a simple in/out with no decent baffling to help make the oil drop out of suspension. The inlet and outlet tube are often very small requiring modification to make them a decent size.

My favorite would by a good cyclone that drains into a catch can - then any old catch can will do as the cyclone is doing all the work and will do a much better job than most if not all catch cans (except maybe a custom build). This means the catch can has to be mounted fairly low to let gravity do its job so it could be difficult to get to to empty. I've even got one you can have if you like?

If a cyclone is used there's two places it could be installed:

1. Connected in series with the existing ccv system as close as possible to where the tube comes off the head. All tubes should be big diameter to reduce clogging and slope downhill to aid the glupe draining towards the catch can. You might have to drain the catch can quite regularly it will catch oil and water. This has the advantage of reducing the clogging of the OE ccv system and probably extending its life.

2. Connected in series with the return pipe to the inlet manifold. This will only reduce the oiling into the manifold but will likely mean the can doesn't need to be drained as often.

Not sure which would be the easiest to fit on your engine.

[Herbmiester 931]

I see you have a 135i, catch cans and N54s go together, The PCV on an N54 is a bit weak and with direct injection keeping oil out of the intake helps stop carboned up intakes.