Rear engine oil seal repair

pmaronoff · Post by **pmaronoff** » Fri Jul 31, 2009 8:28 pm

Just happened today. Oil leak at rear of engine near auto trans. Leaks all over exhaust, smokes and smells and leaves puddle under car. I recall reading about DIY rear seal replacement in Technical section but could not find posts. Is this an expensive fix? Is it possible to do the job yourself without engine R and R? Thanks in advance.
Paul
1980 528i Auto only 78,000 miles

T.Hanson · Post by **T.Hanson** » Fri Jul 31, 2009 11:20 pm

Be sure it is the rear engine seal. That it's an auto lets out the famous seal on the shift rod, but the oil temp sensor ( looks like a short spark plug on the back of the head near the firewall ) can leak, as can the rear cam cover. ( on the firewall end of the head also.)

If it is the rear engine seal you'll need a hoist and the tools to drop the exhaust, drive shaft, trans and bell housing. Look at the exploded parts view on realoem.com to see what is involved.

Depending upon the oil loss, sometimes we choose to replace the oil rather than the seal, for time and cost reasons.

wkohler · Post by **wkohler** » Sun Aug 02, 2009 5:42 am

Given that the leak is hitting the exhaust, I would think that the leak is coming from higher-up, like the Oil Pressure switch. If the rear main was leaking, it would come out of the bellhousing, though in my experience, they don't tend to leak much. Either way, the switch is cheap (about $10-15 depending on source), so I'd do it first.

pmaronoff · Post by **pmaronoff** » Sun Aug 02, 2009 2:49 pm

Thank you all. I will look into both places suggested and post anything I find. The car drives great and is not overheating at all so I don't think it's the head gasket or cracked block. Thanks again.
Paul

T.Hanson · Post by **T.Hanson** » Sun Aug 02, 2009 10:17 pm

That oil temp sender is a clunky deal. I've had two weepers, and they were tight.

One totally let go in winter after start up. Like an oil firehose under the hood.

Look at the wire on top. Usually oily and dirty. Wipe it off, next day or so, same thing.

pmaronoff · Post by **pmaronoff** » Fri Aug 07, 2009 12:37 pm

Oil pressure sender was the culprit. It is less than two years old and leaking out of the top where the wire hooks on. It appears there is an indentation under the sender where the oil would pool and then empty when I went up hill dumping a significant amount of oil onto the exhaust pipe. Thank you all for your input. I would never have thought about the oil pressure sender because it is so new and the old one lasted twenty years. Thanks again.
Paul

wkohler · Post by **wkohler** » Fri Aug 07, 2009 4:53 pm

You're welcome! Be prepared to replace the new one in another couple of years. I consider them a maintenance item these days.

pmaronoff · Post by **pmaronoff** » Sat Aug 08, 2009 3:46 pm

Replaced oil pressure sender. Easy job, had to go to Sears for 24mm tall socket. Worth the investment because I intend to change that sucker on a regular basis. Not only did the oil leak (spray) stop but several issues I attributed to low idle cleared up so it must also have caused a vacuum leak. The car drives better than before. Thanks again.
Paul