Oil coming out of mushroom rocker intake

[TVROZ]

Hi all,

Hoping for some understanding here.

According to several posts the mushroom filter on the nearside rocker cover is an inlet as part of the crankcase breathing, so why would oil be spraying out?

There is a film of oil on the top of the nearside rocker and it collects and runs down the back - at the moment I believe this might be the source of the oil pooling in the bellhousing, which then drips down to the ground.

Some people have suggested using a catch can but I do not understand how that is needed for an inlet. Using one for the other rocker I get to stop oil ending up in the plenum.

The setup is pretty standard except I have an ACT Twin Carbon Fibre Plenum.

Thanks

[Belle427]

The other rocker cover should be piped to the plenum so a vacuum draws off the pressure.
Is this omitted on the Act plenum?

[TVROZ]

Belle427 said:

The other rocker cover should be piped to the plenum so a vacuum draws off the pressure.
Is this omitted on the Act plenum?

It is piped the same way as standard, hence not sure what is going on

[Belle427]

Maybe take it apart and check hoses are not restricted/blocked.
The other rocker cover should have a wire gauze type filter in it worth cleaning.

[TVROZ]

Belle427 said:

Maybe take it apart and check hoses are not restricted/blocked.
The other rocker cover should have a wire gauze type filter in it worth cleaning.

New flame trap was installed after Chim was put back together and has only done about 3 thousand kms but I will check to see if all is ok

Thanks

[Boosted LS1]

I'd also do a compression check and check the oil level's correct.

[TVROZ]

Boosted LS1 said:

I'd also do a compression check and check the oil level's correct.

Compression already checked and good and oil level has been checked multiple times, thanks

[TVROZ]

Am I right in thinking that the air (mixed with some oil that people remove with a catch can) is drawn out of the offside rocker through the flame trap by vacuum and that is helped by having the nearside rocker cover having an inlet so air can be sucked in?

Bit like providing airflow for a bathroom exhaust fan?

And that maybe this is not working properly so air/oil is being expelled out the inlet?

[Belle427]

Pretty much yes, air is drawn in through the mushroom and vacuum is on the other rocker cover to draw the pressure out.
Some choose to modify this and use a catch can successfully but ive never tried it.
Either the vacuum isn't happening or there is excessive crankcase pressure.
Look up Positive crankcase ventilation for a better explanation.

[TVROZ]

Belle427 said:

Pretty much yes, air is drawn in through the mushroom and vacuum is on the other rocker cover to draw the pressure out.
Some choose to modify this and use a catch can successfully but ive never tried it.
Either the vacuum isn't happening or there is excessive crankcase pressure.
Look up Positive crankcase ventilation for a better explanation.

Thanks. One of the guys here in Oz has connected both rockers to a catch can to manage the pressure better.

[Belle427]

Better for the engine breathing too I should imagine.
Can promote leaks from other areas though ive heard but not sure on that.

[LucyP]

It shouldn't be doing any of this. It shouldn't need a catch can. It shouldn't be blocked after so few KMs. If there is so much blow by to be doing that it's because your engine is knackered.

[s p a c e m a n]

Ignore Lucy, it's just some weird chatgpt bot with anger issues.

Definitely nothing funky going on with the mushroom? These engines tend to piss oil everywhere if they're not getting crankcase vacuum.

[Boosted LS1]

Belle427 said:

Better for the engine breathing too I should imagine.
Can promote leaks from other areas though ive heard but not sure on that.

Yes because the engine block's no longer in vacuum.

[Sardonicus]

Better to have a PCV system in place and working your oil will stay cleaner and last longer too , if you have to have an open vented breather system in place then so be it i.e heavy mods / boosted etc