HP22 auto trans problem

[sfk 0]

Hey there.

Car: '86 318 e30.

Engine: M10

Trans: ZF HP22 3 speed

I replaced the engine in this car. Engine is running fine but very little power is being transmitted to gearbox. I didn't mess with the trans at all apart from draining and replacing the trans fluid. The trans was working fine before I removed it from the car.

I replaced the fluid with trans fluid specifically recommended for use in older european cars (bmw, merc, audi etc). I can't recall brand of fluid but still have the container in shed so can give you that info if you need it.

Anyway. The engine that was used for the replacement was from a manual transmission car, so part of the job involved taking the flywheel off the new engine, and swapping the flywheel and torque converter on from the old engine. Once the torque converter was off, some trans fluid leaked out while it was sitting on the floor. Not a lot. The torque converter was still very heavy which I assume indicates that it was still full of fluid.

The torque converter went on the new engine fine. It has a splined shaft that wasn't keyed or anything. I made the mistake of tightening it up before trying to attach the transmission. Since I had not aligned it propperly the transmission would not go on at all. I loosened up the torque converter bolts, THEN fitted the trans, then tightened it all up.

Once the car was back together I filled up the trans with new fluid. Specs stated 2L but dipstick was still showing nothing. I added another 1/2L which put the level over full. Oops. I went for a test drive at this stage but even though there was plenty of revs from the engine, there was very little power at the rear wheels. Like, barely enough to get up a gentle slope. I went on thinking that a bit of driving would work all the fluids round to where they needed to be.

The power did improve a little but nowhere normal. I have looked in the service manual for the car but there are no special instructions regarding the torque converter removal or assembly. I thought maybe the unit needed to be charged with fluid before installation.

So my question is: did I do something wrong? Will over filling the trans fluid result in lost power? Did I install the torque converter wrong? Did I use the wrong transmission fluid? Have I dislodged some gunk that has bogged things up?