Garth S

I've got the front end of the '80 stripped out for a timing belt, tensioner update, etc. Some of the "etc' is to locate one or more oil leaks high up on the front of the block.
The first one seems too easy, because it is the distributor shaft seal (a translucent 'semi' o-ring); however, it turns out that there is more ... at the front of each cam tower. This slow leak is wicking oil onto the exhaust manifolds at cyls #1 & #5, and is the source of a burnt oil aroma!
All rotating seals are dry ( two cams, oil pump, and crank). The oil appears behind the cam seal housings where they bolt to the cam covers. I've checked out PET5, and there is a 52X4mm O-ring seal between these pieces.
Reading on, there is a note "see tech Info, GRP.1 NR5" indicating a 52X5mm O-ring. ( which I haven't yet found) So, on to the question....
- Has anyone experienced oil leaks in this area?
- Is the increase in O- ring size (52X4 to 52X5) done to correct a sealing problem? - for there seems to be no other part # changes.
- is there another oil source in the area that has me looking in the wrong spot ? ( ie., cam/valve covers - although they seem tight)
If you've BTDT, know of the tech note, got a cure, ...., would apppreciate some insight or redirection.

GlenL

No leak there for me, but that O-ring seals the front part of the cam housing to the rectangular cam tower. The cam towers are the same on both sides just with one end getting a cork seal and plate (the back) and the front getting a piece that is a bearing for the cam and holds the distributor on one side.

The O-ring shouldn't fail, I'd think. The seal at the cam is more likely.

Garth S

Glen,
That's what I thought too; however, I've removed the cam gears to confirm, and the cam seals are bone-dry. I thought all the oil came from the distributor shaft. That was only partially correct, for the same oil pattern is at the seal housing/ cam cover interface at each side.

Garth S

A brief update on the oil leakage hunt. As the front seals were dry after removal of the drive gears, the end housings were removed. The large 58mm o-rings were showing cracks/ stiffness - and were leaking. Not shown on PET5 (but in the WSM) is a 13mm oil gallery seal on each side (small brown 'plug' in the attached pic) which was also leaking.
Collectively, the gallery seals, O-rings and distributor seal were passing enough oil that weeped down the left side to make it seem like an oil pan gasket leak: the oil on the right side was slowly torched off by the exh. header.
Before starting this, I was convinced it was all due to an oil pan gasket: as it turns out, that gasket is passable. The total leakage was small but annoying as it caught the hot header - so if you think the pan is leaking and oil is blowing around wetting the side of the block - also check higher up as well.

Garth S

...... and now that the leak has been found and the mess cleaned up, the engine is now ready for a fresh handful of seals, timing belt, ...., all the usual $$
I'm glad to have opened the rest of the cam drive gear because in addition to believing the pan gasket was leaking, the next suspect was the cam cover to head gasket: replacement of that was not in the labor plan!

hupp

Garth S,

I've recently removed my engine and installed a gasket set. I also found that the large o-rings that seal around the front cam journals are sold in different thicknesses. The important thing to notice is that when the o-ring has been installed in its groove, it "stands tall" relative to the outside diameter of the journal. The intent is that the o-ring will compress as the journal is installed into the cam housing. I have a '79 and the o-rings that were supplied in the gasket kit were 52x4 and it was obvious that they would not seal when installed. I subsequently ordered the 5mm dia rings.

hupp

Garth S,

One other thing worth noting is that the area that the o-rings seal is not high pressure area and I tend to agree with GlenL that these rings are not likely to leak. You may as well replace the cam shaft seals while your in there -- but you've probably planned on doing this anyway. Be sure to check the cam shaft sleeves (sealing surface) for scratches. If you can feel the scratch when passing your thumb nail across replace the sleeve.

heinrich

For 32V engines the bastard of all leaks is the oilfiller neckleak, because it looks as if every other seal in the engine is leaking .... till you look in the valley and see the gunk and half of Opec there. I do not know a thing about 16V but .... take a look at the filler.

H2

Heinrich is right. Also, there's a breather hose that comes from the area of the base of the oilfiller neck (on 85's anyway) that is a BEAR to replace without removing all kinds of stuff. If old and broken, it also can lead oil fumes, resulting in oil all over, particularly on top of the manifold. Therefore, some shops will replace most hoses but skip that one and a couple of others that are hard to get to. I was encouraged by a Glen on the list and replaced mine with a LONG skinny screwdriver and a couple hours of "learning" (without removing the manifold). Getting the clamp screw oriented so you can get to if by treading the screwdriver to it's head from the front of the car is the difficult part. (w/flashlite wedge it around to the right orientation if it's off. It has to be about perfectly lined up). Kinda like walking a tightrope in the dark. I could do one now in 15 minutes I think. Like everything I've tried on the 928, the first time is the worst time. Might as well learn since each job makes the next one seem doable.

Harvey

Quote:"For 32V engines the bastard of all leaks is the oilfiller neckleak, because it looks as if every other seal in the engine is leaking .... till you look in the valley and see the gunk and half of Opec there. I do not know a thing about 16V but .... take a look at the filler." Heinrich

Garth S

Good point Scott: I have spare spacers in case the seal has grooved them, although they were dry in service. I suspect the 13mm oil gallery seals were the worst, although the journal o-rings have little 'spring' left in them. The distributor seal is the worst and oil was passing there..
Well Heinrich, I'd probably lose sleep even thinking I had the bastard of all oil leaks about to happen, so the gaskets are on the way: The filler has always leaked some (squishy cork underneath), so you correctly prompted the repair. The 16v is simple to do - once the fuel piping and thermo housing is out.
Fortunately Harvey, I don't think I'll need to borrow your specialized left handed, long shaft, laser guided screwdriver for this one - the 16v is often so much easier to get around than a 32v.