Folks,

Can some of you tell me what I would/should expect if I were having a front main seal leak problem?? I think this may be a problem I'm having...but before I go down that rabbit hole....you know the drill!

Thx!

 

A dribble of oil from the front seal. This would blow all over making crisp identification difficult. With the 928 belt covers it's hard to really identify the source until you're deep into it. Maybe try using a mirror to look into the gap area.

 

GlenL, ahhh that seems to be the symptoms. It does seem to be blowing a very fine mist all over, however, mainly on the alternator side. A few days ago, I cleaned everything down with solvent. I ran the motor for about 15 inutes. Then I saw oil dripping from behind the alternator bracket, on down to the bottom of the alternator. The key thing that bothered me was it was behind the bracket where the oil drop was forming.

 

Hmmm...a drip behind the alternator bracket is too far off the left. The front main seal would drip on the top of the oil pan dead center. And it would blow more or less everywhere, as Glen said, not favoring the left side.

A common leak source behind the alternator is the oil pressure sender seal. Also, I would give a close look at the the oil hoses and their fittings. They are in that area as well. One might be loose or have pinhole leak.

 

Bill/Glen,

I replaced the oil filler neck seal and the sender next to it that sit on top of the oil pan. I also tightened up all visible oil pan bolts. I then cleaned everything up. Oil seems to form at the top of the alternator bracket and then work itself down to the alternator and then eventually drip to the floor.

What about the oil pump seal? Could that be the culprit?

 

oil pump seal would be in front and low, sounds like your leak is higher. You need to determine if it could be from the head or cam gasket if it isn't the oil cooler lines.

 

Stan, unless I'm missing something, I don't have any oil cooler lines. Atleast that I know of that are visible...??

 

Some 928s didn't have them. I would expect you have threaded plugs instead, so perhaps they are leaking?

 

Yes, oil pump seal would be a good candidate. Combine a TB/WP job with it and do the front main seal at the same time. The PET shows oil hoses for 78 on, but I don't know if they are there or not.

 

Yes, I have the threaded plugs instead. They did not appear to be leaking at all. <These were originally one of suspects.>

 

 

Let me guess.....you just finished the TB/WP.

 

Well...not that blatant, but I just put a 'new' rebuilt engine in the car that had the tb/wp done within the year....coming from a reputable rennlister...

 

The source of a similar slow oil leak on my 16v was traced to the cam gear backing plates: the camshaft front seals were OK, but the large O-ring and small oil galley seal to the distributor behind the backing plates where they bolt to the cam carrier were cracked & leaking ... both sides. If in there, also replace the translucent distributor shaft O-ring.

An oil leak fron this location is tricky to ID, for everything flows down behind the rear TB cover.

 

I am banking on a very similar leak on mine being the oil pressure sender unit. I have it dripping off the bottom of the alternator and down the cable covers, and also spraying back onto the exhaust.

The deciding factor for me was seeing bubbles appearing between the plastic and the metal where the connectors are.

But you never know....I have just done a TB/WP job including front crank seal, and I have not discounted it being related.

Cheers

Colin