mysterious oil leak - BMW Forum

82_320i · 01-29-2009, 11:42 AM

there is a small/slow oil leak somewhere on the back side of the motor. i cannot trace it any higher than the top of the oil pan because i cant see up any farther. but im pretty sure the leak starts past that point. also sometimes there are oil droplets on the bottom half of the front of the transmission. if it turns out to be the rear main seal do i :

a.) have to pull the motor to replace?

b.) would it be wise to go ahead and rebuild the motor?

marti5 · 01-29-2009, 01:07 PM

A 320 engine is pretty straight forward to pull out, thats what I would do then you can change loads of things, get the engine clean and the bay.

Celsdogg · 02-05-2009, 01:15 AM

it is most likely the rear main seal. you wouldnt be able to tell for sure tho until you dropped the tranny, but it is the most likely spot. when i pulled the tranny to replace the clutch, the rear main was accessible from what i remember. it is probably easier to drop the tranny then to pull the motor and tranny all together, except for two torx bolts, one of the ones on teh starter, and one near the topside. still, easier to drop the tranny tho, just have some extensions handy

silversled · 02-05-2009, 08:18 PM

how much oil is it leaking? like a quart every 500 miles, a pint every 100 miles? there are various ways to aproach something like that based upon severity. especially on an 82...law of diminishing return

Celsdogg · 02-09-2009, 05:07 PM

in both my E30's i went through about a quart every oil change/3k miles. both had oil leaks.

i read somewhere (i think in my bentley) that for the M20, BMW only considers oil leaks major if its a quart every 300 miles, 300! thats alot i think. . .

fj-cruizer · 02-19-2009, 01:53 AM

Are you sure its oil?It May be the short hydraulic line that couples into the Slave cylnder,In my case it was actually the Slave Cylnder itself.Check your Brake/Clutch fluid Reservoir.Let me know how you make out>

735i-BMW · 11-13-2010, 10:15 PM

i bought a 92 735i and it has an increasing oil leak coming from the back of the engine and pouring down the sides especially the left causing my car to smoke

please help is this a rear main seal?

beauard · 11-14-2010, 10:38 PM

Sounds like a valve cover gasket for my two cents...the rear main leaks oil in the tranny area. Best to clean engine and then you have better idea. Good luck

Markdas · 11-18-2010, 07:46 AM

I agree with the last comment.....or at least start in that area, wipe it all clean at the top and observe it over a few days. If its not the valve cover gasket then the two rear cam shaft seals can go hard and crack, they are cheap and easy to change!

Rear main seal can fail and is a big job!