About ten days ago I decided to change the transmission fluid of my old 740 turbo, automatic AV 71.
I did not flush the whole system , instead I drained the fluid in the pan and start Filling with new fluid. I didn’t pay attention how much I drained , so I overfilled the transmission. Afterwards I saw in the rearview mirror that from time to time I was leaving a wet trail after me. Few days later I got a nasty growning noise somewhere underneath – I am quite sure that It doesn’t come from the engine – I checked the spark plug wires , I do not know about the timing – Hopefully the engine is running raugh. I drained some fluid few days ago , after that noise started, to get to the normal level.
My question is : is it possible that I did some damage on the transmission , by driving for few days with overfilled trans? If somebody had gone through something similar – please let me know!
I hope that I didn’t ruin the trannie, what should I look for – I read in the FAQ about similar vibrations – the engine mounts I replaced Last year, The exhaust system looks intact, the transmission tailshaft is not leaking, where else to llok for the culprit?
Thank you in advance!

These trannys are pretty solid from everything ive done to it and seen about them, i just sadly rebuilt an 86 tranny and threw it into my 89 if your getting weird noises or your fluid is messed up take her out and do a rebuilt, will save your life down the road plus youll know youll get at least another 200k if kept up properly, took me 1 day for the rebuild and another 1 day to get it in an out not to bad of a job just a huge mess and about 2 days worth os cleaniëg it up, if you decide to drop the tranny out make sure to replace the rear engine seal while at it that will save you some money and time in the future too.

Hopefully you've already found & corrected your problem by now, but if not, here's something to check.

I've found a few AW71's with the noise you describe (so it seems). In your filter kit, did you get a small gasket that goes between the strainer & valve body? I've seen these slightly off placement several times. When they're not lined up correctly, the strainer doesn't seal to the valve body correctly & you end up with a multitude of problems. The first symptom is pump noise (as the fluid is pumped through the aw71 & circulated into the pan, it tends to get airated, the strainer pulls double duty as ensuring that the airated portion of the fluid doesn't get pulled back into the tranny.) The concerns just get plain nasty after that.

Another check, Make sure your case vent is clear & unobstructed.
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85 740 gl NA manual trans 87 740 gle NA zf trans 88 740 gle turbo wagon AW trans, loaded & fun.

Thank You guys!
I spent about five hours under the car - Changed the strainer/filter and the small gasket - Once I uscrewed the strainer a lot of dirty fluid came down.
I am sorry , but where is that case vent - on the driver side ?
The other thing I figured - the extra trans fluid did a great job on the trans mount- the trannie was basicly droped on the support beam - the whole rubber ( because it was old as well ) was gone! I think that the trans fluid interacts with the rubber and speeds up the process of deterioration of the mount.
So the noise was coming from two places - the pump had hard time and the trans was touching the support beam directly - metal - to - metal.
I lifted the trans slightly and (for temporary solution)slided in a pice of rubber - Now The Old Swede is running quite!
ohh - by the way the bolts which hold the pan are very weak - be aware - I shreded one of the ... Ithink that they are not swedish!!!
Thanks Again!

UM, i hate to say it, but I overfilled my tranny. Lost a lot of fluid out the rear seal though and got it back to where it should be.

TERRIBLE NOISE? Sounds like your pump not getting fluid. you need to replase the pump filter. this is easy, though messy.

I had the same problems as you, sounds like almost to a tee.

New fluid will pick up and circulate old sediment... possible that it is lodged in your filter.

My tranny flush caused me great heart ache. I wish the previous owner had kept up on them... probably wouldn't have gone through what I did.

Good luck

Thank you for your responce - I hope the pump is not dead - so what happened is that the sediments were somehow settled in different pockets of the trannie and the overfill made them free to float around?

The Pump filter is the small mesh that comes with the pan gasket - I bought a "filter kit " for transmission - it comes with a big pan gasket and a small metal frame with mesh filter - so I have to do that before something bad is going to happend.
Thank you again!