Here are the facts:

Every time I run the car for any amount of time, when parked, it deposits a 3-inch spot of oil. Oil drips from the transmisison support, midway between the transmisison mount and the bracket which secures the exhaust. The oil is clean and seems to come from directly above the rubber transmission mount.I periodically have to refill my trans/overdrive with 30w Non Detergent.There does not seem to be an abnormal amount of oil coming from the bell housing weep hole, in fact, barely any. (I've had Volvos for 30 years and know about rear engine seals.)

If I had to venture a guess, I'd say it's comning from between the trans and overdrive. Does anyone have experience, recomendations? Could it be as simple as tightening the bolts which secure the OD to the trans? Could it be a seal or gasket failure?

I have a rear U-Joint that's going so I plan to take the driveshaft out, replace that, and examines the center support bearing on the shaft. I understand that the OD can simply be unbolted and removed without taking out the transmisison (I have an M410 so the bell housing has to come off with the trans.) But my goal is to repair that leak with the minimum amount of screwing with the overdrive.

I'll await your sage advice.

Tighten the top two nuts on the rear of the OD unit. There is normally a copper washer under them but over time the nuts work loose and the oil comes out from under the washer.

This is the most common area for leaks. Rarely between the OD case and the trans adaptor.

The gasket to the rear of the center metal ring can be replaced without removing the OD fromm the trans. The rear case just comes off.

IF the front gasket is leaking, the OD has to come off to replace the front gasket. To remove the brake ring,(metal band), the cone clcutch must be released and it is held by nuts accessable only after the OD is off the tranny.

If you take it off this far, replace the two O-rings on the actuating pistons. These should be considered a wear item and if accessable replaced "just because". A cost of about two dollars now will save you from pulling the OD later when it fails to engage at a later date.

Duane

I had a similar problem with my '85. On my OD unit the gasket next to the stationary "clutch cone" split and opened up on the top of the unit. That is the steel/iron part sandwiched between two of the aluminum housing parts. I couldn't find the leak until one day I put the whole car up on stands and ran the engine with the transmission in gear. I then found the transmission fluid comming out of the top of the unit at the place where the gasket had split and poped out of place. (Maybe some previous mechanic had over tightened the bolts forcing the gasket out?)

I was able, following the procedure in the Volvo Green book, to remove the OD from the back of the transmission while the transmission was supported on a jack. (Drive shaft and center bearing were dropped out also for inspection as the car had over 100K at the time.) The OD unit had to be taken apart to replace the gasket so I got all new gaskets and internal "O" rings to do a low cost "refresh" of the unit. About a day's worth of work. I really needed the "Green" book as there are several "tricks" to working on it. (I had one on my old Triumph TR3 apart years ago but had forgotten how most of the stuff went together.)
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'96 965 with 16' wheels at 101K. Had '85 745 Turbo Diesel for 200K.

Obviously check the bolts for tightness... they are supposed to have locking tabs on them, but don't always.

There is no way to replace that gasket with the trans in the car. Noooo way.