Can i replace the rear main oil seal in my 1983 928S porsche automatic without taking the motor out?

If had someone replace the seals you should take it back to them and let them fix it.
You can remove the oil pan without taking the motor out, but it's a LOT easier to work on if you do. You will probably take 3 times longer by trying to leave it in the car vs. taking the motor out.

Lots of tools!!! engine crane, engine stand, tranny stand, fluid collections buckets (collant, engin oil, tranny oil, transfer case fluid.
Remove transfer case, remove tranny. drop oil pan, lossen off rear eng bearing and remove slowly, remove seal materiial from upper seal have, install new seal material in both halfs, reinstall bearing and turgue to specs for bearing, install new seal and reinstall oil pan, reinstall trannt, reinstall transfer case, refill all fluids. start it up and check for leaks everyday for next week. it take 2 people to reomove case and tranny. it wiil take 16-18 hours of constant work for an experienced DYI

If it is motor oil, it should match the oil on the dipstick.
If it is automatic transmission fluid, it should be sort of redish and match your "tranny" fluid on that dipstick.
If it is thicker than motor oil, it should be manual transmission oil.
Motor oil leaks from the "rear main seal".
Transmission fluid or gear oil leak from the front transmission seal.
All 3 of these can look like they are coming from about the same place, where you have said.
All three of these require you separate the motor and transmission to fix them, and that means taking the transmission out of your truck.
Pretty expensive if you pay to have it done.
If you take the " tranny" out, most shops will replace both seals (one front, engine and one rear, tranny)
Depending on how much it is leaking and other things, lots of people let it leak.
If you are using a lot of fluid, perhaps it\'s time to think about repairs.
Be blessed

Could be a couple of possibilities that you'll have to get into looking for. Rear oil pan seal, rear main seal or occasionally rear intake seal will leak down back side of engine. Wipe down motor or spray w/brake clean and watch for leak.

The Rear Main Seal is the main area for an Oil Leak on the Transmission Side. You will need to drop the transmission to remove the old rear main seal and install the new one.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

Hi,
Well, there several ways that I know to handle this.
FIRST: Don't go back there.

If you only have 26,500 miles on a car that is now 7 years old, you are not using it very much.
I don't even consider your car as broken in.
The assertion that the car needs a new bearing in the engine sounds to me as though the technician had the apparition of the angel of money appear in front of him while working on your wallet (I mean Porsche).

SECOND: The usage on your car is so low that, if you took it on a trip, the leak might very well
stop completely, on it's own.

THIRD: There is an excellent bottle of leak stopper sold at Walmart that handles rear main bearing seals. It costs about $3,994.00 less then your previous estimate. I used it on a really serious front main bearing oil leak (usually this sort of product won't work well on front main bearings) on my 23 year Mercedes with 166,000 miles.
I hope this helps,
Best Regards,
Mark

That's it? Any more info.? The web is full of info on the problematic rear main seal (RMS) and intermediate main shaft (IMS). Take a look.

you dont have too pull the motor!!
remove the radiator shroud, remove the distributor cap and rotor, take pipes lose from exsaulst manifold, take out motor mount bolts pick the engine up with a hoist, you now have enough room too drop the oil pan!!remove rear main bearing cap, take lower half of seal out of cap, too remove the up half of seal ,i use a small screwdriver too slide it around the crank ,
grease up the new one and it will slide right in!!
in spect the rod and main bearings while you have it apart and think about replacing them they dont cost much about 4.00 each and if you go that far replace the oil pump its not much either under 30.00!!

There are only two paths for oil there. The rear main, and a oil galley plug a little higher up, about 2 o'clock.

First is it a front seal ,or rear main seal,(front seal,being were you see the pulleys and fan belts,,you have to look at the bottom pulley,follow the shaft to the motor,where the shaft goes into the motor is the front seal,the pulley and everthing behind it has to come out then you pull out the seal,auto zone actually has free tool rental that you can pull the seal,and a tool to put it back in,if a rear main seal its where the shaft from the transmission meets the back of the motor,youll have to pull the trannsmission back,check where you see the oil leek from,the front seal you can do if mechanically inclined,but if its the rear you should take to a mechanic,if this helps please give me a fix ya vote