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Discussion Starter #1
I am posting in E46xi forum because of added complexity of where oil leaks come from and some of the fixes. Please check this thread as well: http://forum.e46fanatics.com/showthread.php?t=882732

Main Idea: DON'T worry about replacing oil pan gasket or rear main seal for the crank UNTIL you loosen and correctly re-torque the oil pan bolts.

'05 325xi, manual transmission, 146K miles now - bought it 2.5 years ago. Within the past 18 months I have done VCG, CCV, OFHG, VANOS. I change oil at 5K intervals. I noticed a slight oil sheen on pan at 135K oil change, but could have been from oil change, so I waited. A sniff test of the oil confirmed it was not differential or transmission fluid. At 140K there was a definite leak - puddle on the bottom of the oil level sender held to the pan with 3 nuts on stud and on the belly pan. I checked those nuts and tightened (ONLY to spec, you can wreck your pan if you over-do it ! 10Nm / 89in/lb - use appropriate wrench). This did not help, so for the 145K oil change I had a new gasket for the oil level sensor. I removed it, checked it, and reinstalled it - tightening to 10nm (89 in/lb).

This did not fix the issue - the oil still accumulated on the sensor and its cable (key observation - cable is above the sensor). There was no seepage from the front or side of the block coming down, but the oil pan bolt next to the sensor cable had oil on it and I could then see a film of oil on the front drive shaft to the diff. Oil was dripping off of the bolt, onto the shaft, being flung every direction, but mostly onto the sensor cable.

Back to consulting this Board, and I found the message NOT to jump to replacing oil pan gasket or rear main seal for the crank UNTIL you loosen and re-torque the oil pan bolts. ONLY torque to spec with a good small-torque wrench to avoid stripping your block. LOOSEN each bolt slightly before re-tightening, because it's had over ten years of corrosion to lock itself into place, and your goal is to re-establish the intended tension, but not over-tighten.

RESULT: Ran the car for half an hour, and everything is absolutely dry !

Interesting details: 1) RealOEM.com shows a normal E46 oil pan illustration instead of the E46xi, so it is less helpful about accessing bolts (check ECS for photos), 2) Bentley shows pan for early xi's only, and 3) Two rear end bolts are reached through holes in the transmission and are highly blocked by front subframe - I used a short 10mm 1/4" socket, a universal, and about a 2.5 inch extension to access.

Mariner05
 

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Discussion Starter #3
The leak was noticeable underneath by eye in 30 minutes of running - but the rate hadn't gotten really bad yet. I was losing about half a quart on the dipstick in 3500 to 5000 miles. My car had not been burning any measurable amount of oil between the 5K changes, so this got my attention. It doesn't take a lot of oil to make a real mess of the belly pan and bottom of the car. I was most concerned about the rear main seal giving out before I'm ready to replace the clutch - or the effort it would take me to remove axles and differential to replace an oil pan gasket.
 

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Mine is so slow I have to wait a few days to notice it. I haven't kept track in miles but I add about 1 qt. (or a tad less) per year.

Well, the first thing I'm going to do is clean my horrendous-looking lower engine which is covered in crud, then add tracer dye. I want to be 100% sure it is the oil pan gasket and nothing else.
 

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Interesting details: 1) RealOEM.com shows a normal E46 oil pan illustration instead of the E46xi, so it is less helpful about accessing bolts (check ECS for photos), 2) Bentley shows pan for early xi's only, and 3) Two rear end bolts are reached through holes in the transmission and are highly blocked by front subframe - I used a short 10mm 1/4" socket, a universal, and about a 2.5 inch extension to access.
Mariner05, did you notice if any bolts were different in length? Realoem lists 25 oil pan bolts total, with 9 of them being long (#6 and #7 in the diagram).
 

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Discussion Starter #6
Update on my 'fixed' leak - it was slowed, but not fully stopped. Because I am replacing axles due to cracking CV boots, I decided to do the oil pan gasket at the same time.

I am now in middle of that job, doing a little each day. Yes, there are indeed a total of 25 bolts, and three sizes of them. I haven't done the check on my own car, but I expect that RealOEM is correct in the count and lengths even though the illustrated pan is for a rear drive car. When I'm finished, I'll do a post on any aspects of my DIY which are not covered in existing threads on this board.

Mariner '05
 

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Discussion Starter #7
Update:

Yes the oil pan gasket was the leak. At least not a rear main seal! Finished this job. I might not have done the job except that I was already replacing axles - and would I want to do all that a second time? And of course, with the axles out I could tell the RF wheel bearing was toast, so I ended up pressing in new wheel bearings as well.

Now after driving 5 days with the belly pans off so I could keep checking it's all dry, and I put the pans back on. I know more than I even wanted to know about how all those parts in the front come apart and go back together. Did this over several days spanning a couple of weeks as I had the time.

Mariner05
 

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Need to do the same thing but will double check first for other leaks/retorque.
How high were your jackstands, can you do it with ramps + 2 stands?
Did you needed an extra jack for the front diff?
How did you put the subframe back with a spare jack?
Did you replace diff seals, axle guibo, steering?
 

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Discussion Starter #9
Need to do the same thing but will double check first for other leaks/retorque.
How high were your jackstands, can you do it with ramps + 2 stands?
Did you needed an extra jack for the front diff?
How did you put the subframe back with a spare jack?
Did you replace diff seals, axle guibo, steering?
Definitely just retorque bolts first - careful not to strip !

More complete description of what I did is here http://forum.e46fanatics.com/showthread.php?t=1114860

a) How high - about 16". I would not personally try to do this without 4 jack stands, plus extra to handle drive shaft and subframe
b) Used two jacks lowering / raising subframe - platform jack for the diff
c) Raised the subframe, got close, used Old Front (Long) bolts in the rear to line up the subframe to the car, jacked up carefully, installed New Front subframe bolts in the front, then replaced Old Front bolts with the New Rear bolts in the back
d) Absolutely replace O-ring seals and axles seals w OEM to avoid leaks - I didn't replace Guibos since mine were both free of cracks and flexible

Mariner05
 

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So here is a million dollar question , may be not.... I am sure this may been talked about before.

Why do Honda, Toyota and such cars oil pan gasket don't have similar issue? I wonder if its just bead of gasket maker sealant or an actual gasket. I wonder if anybody has tried using a heavy duty gasket sealant instead of the BMW OE gasket.
 
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