Turbo oil caps

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

I know the gemini cap is shitty and I cant get it to stop leaking oil due to boost pressure etc. What do i do?

GasGem · backyard mechanic Joined: 05 Nov 2001 Posts: 755

Hey Loz,

I bought a brand new one and it has fixed the same problem.

also it depends on what breather type you have on the back of the rocker cover if it is a restrictive setup then the oil starts looking for other ways out...

cheers

TXcoupe · petrol head Joined: 05 Oct 2001 Posts: 1675

loz maybe you could modify a gem rocker so that the oil cap has a thread? maybe weld a large diameter pipe to the oil hole put some thread on it and make up a cap with some thread on it aswell?

rust3 · backyard mechanic Joined: 04 Feb 2002 Posts: 971

araldite the cap onto the rocker cover.

when you need to change the oil, simply take the rocker cover off Smile

rust3 · backyard mechanic Joined: 04 Feb 2002 Posts: 971

by the way, i was being sarcastic ; )

Poida · Posted: Tue Jan 06, 2004 7:56 pm Post subject: Re: Turbo oil caps

The crankcase vent system on stock Gemini engines used a vent into the air filter housing to relieve any pressure difference in the crankcase.

If you have modified the air intake and not incorperated the vent you might find pressure buildup is forcing oil past the oil filler cap.

Sometimes a blockage in this original vent line causes such an oil leak past the cap. The line is very small diameter and a larger pipe could possibly assist oil to fall back to the sump instead of it being pumped out the cover.

In a sound engine the pressure leakage past the piston rings shouldn't cause problems. You may need to consider a rebuild.
_________________
I try to tackle one day at a time, but often several days attack me at once.

(The views I present are my own and NOT necessarily of the administrators or other members of this site.)

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

Its funny coz I bought some more aroldite today.
I have just never had a cap that sealed properly, and now with boost it leaks a shit load. Too much for rego to pass me.

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

Its a brand new engine. I think the main reason it is doing it it because when the engine is new, the compression goes past the oil and comp rings and aids in bedding the rings in, until they are the same shape as the bore and no moree can escape. As my engine still only has a couple of hundered km's on it the rings havent properly sealed yet.

rust3 · backyard mechanic Joined: 04 Feb 2002 Posts: 971

personaly i wouldnt worry about it. my brother had a G200 turbo, and use to leak all the time. passed rego every year

maybe you should try running a bead of ultra copper/blue around the edge of the cap and leave it to dry. put it on once its dry, if all goes to plan it should act like a gasket

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

I think that your engine condition is not a concern, most engines do this under boost, as there is a fair bit of blow by, even with good rings.

The breather at the rear of the rocker cover is simply not breathing enough air from your engine. The breather has a baffle under it, maybe you can modify this baffle to allow more flow. Maybe the breather you have hooked up is too restrictive, with the air filter being to small on top of your oil catch can.

I am personally adding another breather line to my rocker cover, as I get a fair bit coming out too under high boost on the dyno.

Also, a brand new cap is fresher rubber, and is more flexible, they are about $10 from auto shops. That bead of silicone might be a good trick as well like rust3 suggested. A bit like an o-ring.

Ben

GasGem · backyard mechanic Joined: 05 Nov 2001 Posts: 755

try and put a rag over it then push it in and see it that fixes it..

cheers

Bugle · tinkerer Joined: 08 Oct 2001 Posts: 221

Piazza turbo one is the same as a Gemini one and it doesn't leak very much at all.. Sure there's not someting wrong with your engine to produce so much blow by?

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

yeah...its not run in yet. But i think by making the breather breath better and getting a new cap it it alot better now.