Outer Limits 4x4 Board

On the top rear of my GQ TD42 rocker cover, there's a large round thing which I assume to be some type of breather (?) or pressure relief (?)

Whilst I don't really know what it is or it's purpose, it does appear to be leaking reasonable amounts of oil.

So, my question is this... What is it, what's it for, and is the leak likely to be some simple seal?

Any guidence gratefully accepted. Thanks.

its an air control valve but i dont know what it does

It's simply a breather, crankcase pressure has to go somewhere. If it leaking a lot of oil you may have a serious blowby problem.
There is a gasket that goes between it and the rocker cover.

Cheers, Jeff.

Thanks Jeff.

It's been doing a lot of long high speed highway runs lately (it normally spends most of it's time chugging around town or out in the bush), and I've noticed that the top of the rocker cover is VERY oily. I can't see that the oil would be coming from anywhere else....

doh !

why have you got rockets in your motor?:S

and tis not normally a huge issue, unless you can see puddles of oil you will generally find its just a very fine mist and is alot less oil than it looks

that said if you are realy worried take it somewhere and have the compression checked as chances are the bore is a lil glazed (perhapse from all the chugging. u gotta give them a good rev occasionally) or the compression rings are a lil worn

why have you got rockets in your motor?:S

and tis not normally a huge issue, unless you can see puddles of oil you will generally find its just a very fine mist and is alot less oil than it looks

that said if you are realy worried take it somewhere and have the compression checked as chances are the bore is a lil glazed (perhapse from all the chugging. u gotta give them a good rev occasionally) or the compression rings are a lil worn