I found a oil trail down the street leading into my garage. Looked under my 240z and found a very large oil puddle coming from where the tranny and the engine meet. I believe its the rear main seal. If so do I need to remove the engine and tranny or can I just drop the tranny. I tried researching the proper steps on replacing the rear main seal but met with no luck. My Chiltons book says to remove engine.

Remove the transmission and take a peek.

Rear main seal can be changed with the engine in the car.

BUT: If it's a really big leak, what have you done recently to the car?

Normally the rear main seal doesn't leak that badly or just start suddenly.

haven"t done anything. Its been leaking a few drops for quite a while so I used stop leak and it did stop for sometime, but I guess the seal can only take so much. I'm pretty sure it's the seal. I never performed a big job like this before. looking forward to the challenge. once I remove the tranny is the seal on the tranny or on the engine?

Did you look at oil filter and sending unit.

I had a leak before, it was located apparently from the same area as yours.

I've checked everything at the time and found it was coming from the window on the front of the engine on the head. I was missing a gasket. Oil was flowing along the engine until reaching the floor much further away...

To solve it, it was a matter of removing 3 bolts, put some liquid gasket and install back everything. Much easier than a trans to remove

I would wipe the engine & check where oil come from, it should be easier to do on a Z than any other car with the room available around the L-engine.

Edited March 10, 201114 yr by Lazeum

If it is indeed coming from between the engine and transmission, my experience is that sudden, large leaks are seldom the rear main seal. I'd think it is just as likely to be the input seal on the transmission. Is the oil level low in the engine?

If it is indeed coming from between the engine and transmission, my experience is that sudden, large leaks are seldom the rear main seal. I'd think it is just as likely to be the input seal on the transmission. Is the oil level low in the engine?

Plus in most cases the manual transmission oil has a distinctive smell.

Engine oil pan bolts tightish. No cracks in the pan? The sudden aspect of it coming on and enough to leave a trail..... Oil level should be down significantly I'd think.

I'd vote for the wash down and clean up and start by letting the car idle in the garage and watch how soon it starts and where it's coming from. If nothing after idling, then drive the car and park it and give everything a good once over.

I see black fluid coming out of the clutch fork boot. Underneath is pretty clean, I'll also let it idle and watch. Thanks! I'll report back.

Ok it's not coming from clutch fork boot. Oil is definitely down. I filled it yesterday. I let it idle and I saw oil dripping from the plate that separates the engine and the tranny. So it has to be the rear main seal.

So my plan now is to drop the tranny, remove clutch, then the bearing is behind the clutch. Is that right?

Ok it's not coming from clutch fork boot. Oil is definitely down. I filled it yesterday. I let it idle and I saw oil dripping from the plate that separates the engine and the tranny. So it has to be the rear main seal.

So my plan now is to drop the tranny, remove clutch, then the bearing is behind the clutch. Is that right?

Drop tranny, remove clutch, remove fly wheel....

Have you done a finger feel across the back of the block under the valve cover gasket? The amount and suddenness is just peculiar. A broken valve cover gasket would do both....