hello all,

90 model evo with mysterious leak. If the crank shaft seal is allowing primary oil to leak into the crankcase is it possible for the crankcase to retain enough oil to leak at the union of trans and engine without the crankcase breather from puking oil ? I have replaced all the oil lines , sprayed carb cleaner all around the oil pump and cleaned the underside of the engine throughly. I ran the motor on the lift in 2nd gear at 2000 rpm for long enough to heat engine and oil. the oil looks as though it is coming from the union of the engine and trans. has anyone had any experience with a leak similiar to this ? Dealer said there has been recalls on the cases cracking and bearing sleeve slipping in the case and leaking years ago but there was nothing they could do now ...... any help would be appreciated.

latter...................

 

Man, I hope its not the case... I was told, years ago, that the rubber mounted EVO's had some trouble with that when more power was added.. The problem was supposedly due to the inner primary being the only thing actually connecting the engine to the tranny.. Carlini makes a "Torque Arm" to remedy this. It connects the eng and trans on the right side.. Good luck..

 

You mean it's leaking at the engine where the primary meets it?

 

t150vej,

no, i mean it looks like where the transmission and the engine bolt together. not anywhere close to the primary. there are two bolts that hold the front of the engine to the front rubber motor mount and two in the rear of the engine to tie the engine to the transmission. sorry i wasn't clear about the location.

I know the oil pressure sending unit isn't leaking.
I know that the primary seals to the transmission aren't leaking.
I know the primary O ring to the motor is not leaking.
I know the oil pump is not leaking.
I know the nose cone gasket is not leaking.
I know the transmission gasket on the right side is not leaking.
I know the top gasket on the trans isn't leaking.
I know its not the jackshaft seal.
And I know the oil isn't coming from the case breather tube.


thats about all i know ...

later......

 

OK. The only place they can leak back there is either where the cases mate or the studs (thru bolts). You've probably noticed there is one above and one below that mounting flange. It's possible that there was insufficient sealant applyed when it was built. That can cause them to leak out thru the studs that hold the cases together. If that's the source, I can give you a relatively easy fix.

Check really close around the nuts of those studs. And if it's still impossible to see EXACTLY where it's coming from, clean it real good and spry all under there with Sure spray-on deodorant (powder) and it'll show up real easy.

 

Don't forget the starter shaft seal.

 

Also may want to check the crankcase vent line.If by chance youre hose has fallen off or just cracked,it would allow oil mist to blow around that area.But crankcases do leak from time to time.Seen alot of the ultima engines do this.

 

New info, Paco

You may have a cracked case. They can crack on the pinion side at the rear tranny mount boss. There's a thin area on that side and if the corner is machined square, rather than radiused, they tend to crack there... if they're going to.

 

A picture paints a thousand words. Well done for posting that, excellent info!

 

t150vej,

thanks man, if i was a betting man, i would bet all i got on that crack (in photo) being my problem. the oil is coming from that area. i will just have to bust the cases and see, just been ridin instead of wrenching. thanks for the photo,its dead on the leak area.

paco