I recently picked up a pretty solid Z31 for cheap and sorting out some issues. Currently looking for some suggestions on known issues related to AT leaking from inside the bell housing. On my first drive attempt I came up with the following: Engine starts and runs great. AT feels like it is low on fluid - requires higher revs to get it moving. After the trans warms up a but, it shifts and drives ok, but starts spewing fluid from the bell housing. This weekend, I pulled the trans and there is definitely AT fluid throughout the inside of the bell housing, but no obvious point of leakage.

I had no real history on the car, but now that it's apart, I can see that the trans may have been worked on in the recent past. Things inside of it look too clean - torque converter looks brand new - pristine bright blue paint, inside of housing looks shinier than I'd expect to find on an untouched 32 year old car.

Whatever help the experienced group could provide is appreciated - related to known issues or things I should be looking for in my trouble-shooting efforts.

Thanks in advance -

Len

If you are sure it is ATX fluid and not engine oil from the rear main then front seal on trans is likely bad, they can look fine and leak gallons. Past that, incompetent work on trans can have the bushings worn out up front there to locate things and even a new seal may leak then. And there is always the issue of installing the converter without nicking that seal, super easy and ruins seal instantly.

Be 100% rock solid sure the converter is FULLY all the way back in (usually like 3 stepped parts you have to go over to be right) and make provision to hold it in place while the trans is moved about to plug back in, the converter is heavy and often shifts to come part way out and BAAAAAD. A converter not fully in all the way generally tears up both converter and trans in seconds, even starting attempts can do it.

Sound advice - thanks. Definitely ATF. I'll start with the things you suggest.

Can you explain a little more what you mean about the torque converter is fully back in? By my estimation it bolts up tightly to the flex plate and it only has one way to fit once the tranny is bolted up. There was one thing that stood out as a surprise to me. When I pulled that transmission out, two dust cover plates dropped out. They were two different shapes, but both were bolted into place. I had never seen two used. To be honest, I haven't looked at the service manual closely enough to see if they should both be there.

Update:

Got the trans out and discovered that the DPO had installed it with no front seal. As in, the torque converter seal was completely missing. As I mentioned before, there was evidence of trans work once I removed it, and I discovered the missing seal after I got a closer look inside the bell housing. Ordered a new one on Amazon for $10.39 and put it all back together this weekend. Lucky break, but sucks for previous owner. Leak is fixed and AT works great. Somewhere along the way I created a new problem. Engine idles great and works fine below 3000 rpm. Cuts out at 3000 but picks back up once it’s back down in the low revs. I drove it around a few miles and it works fine below 3k. Something new to sort out.