Oil leak on distributor side of engine

I would imagine I'm not the only one with this particular problem so please provide some feedback if you have any.

This is certainly not a major issue but kind of messy and annoying to see.

I have a 99 XJ, 4.0L with ~120,000mi.

Between the head and down to the oil pan, all along the distributor side of the engine, is a layer of oily dust. It almost seems as if there is a slight seepage of oil from the intersection of the engine block and the head.(The other side of the block under the intake/exhaust manifold is clean) I find this difficult to believe since only the push rods are on that side of the engine, there's no oil pressure forcing oil out. If the head gasket can keep the combustion pressures in, how is it that oil can seep out from that area?

It has to be coming from that spot since the head has no signs of oil on it, it all begins from that point down. And it is even all the way across.

Another thing.. About 3000miles ago I switched to Mobil 1 synthetic 10W30.

I was under the truck changing my transmission oil filter this weekend when I noticed a drop of oil right at the engine oil filter. I had never seen that before.
Is it possible the synthetic is making it's way past the O-ring on the adapter?

Any info would be appreciated.

Thanks,
MAP

Well...

Even though there's no pressure on that side of the engine (just drainback under gravity) it's useful to remember that the typical head gasket is designed in "zones" - the compression sealing rings are toughest, the coolant passages are sealed fairly well (only 15-20psi max) and the drainback area is mostly a "shim" for even clamping force and a light seal. Still...

Take the time to clean that side of the engine (I like LPS PrecisionClean) and run it for 15-20 minutes. Blip the throttle a few times. Recheck the leak.

Possible leaks on that side - top to bottom:

Seepage from CCV hoses at very top (highly unlikely)
Seepage from valve cover gasket/seal (quite likely)
Seepage from head gasket drainback area (fairly unlikely, but possible)
Seepage from distributor mount (if present) or oil pressure sensor fitting
Seepage from oil filter adapter o-rings (there are three, and replacement jobs for these are legion.)
Seepage from oil sump pan gasket (possible - and a headache to fix. I'd sooner do a head gasket!)

5-90

Thanks for the quick reply.
Any seepage from the CCV hoses is localized so that's not it.
It's definitely not the valve cover gasket. It's dry.
It probably isn't the distributor since there would be no reason for the leak to travel up and stop right at the head.
The oil filter adapter is a possibility and I'll look into getting those O-rings. Is this a dealer only item? My local autoparts stores don't seem to list these.
The oil pan gasket also isn't the problem.

It has to be the head gasket. It's hard to believe but I guess it's a possibility.

I'm going to have to remove the starter to clean the mess. I like to use simple green. It cleans up oil/grease nicely and doesn't leave the engine smelling like it's been covered in charcoal lighter fluid.

I'll add a bead of silicone right at the engine head interface. If that stops the mess I guess I found the source.

MAP

There are three orings in there - the OEMR parts are around here somewhere, and someone might have posted specs. DEFINITELY do a search to see if someone around your year has done the job - it's a pain!

In most engines, the distributor shaft is also a low-pressure seal, with supply pressure from the oil pump coming up or near it, and the distributor bore usually intersects with one or more oil galleries. Something to watch out for.

LPS works better than SG (y'ask me...) and it doesn't leave any funky smells. It's biodegradable and designed as an industrial cleaner - which probably explains why it works so well (I don't mind "Earth-Friendly" solvents - when they work at least as well as the stuff they're meant to be replacing.)

If you're going to "bead in" the edge of the head gasket, use something sharp to shave the outside edge of the gasket (you want an internal double bevel - kinda like if you were welding two heavy plates) and make sure to press the sealant in well when you work it in. RTV Black should do the job.

5-90

Just curious. Any updates on this. I'm having pretty much the exact same issue.

ya mine leaks at the head gaskes also how bout retoqureing the head???

ceb0217 said:

ya mine leaks at the head gaskes also how bout retoqureing the head???

Click to expand...

If it's on the pax side - where the valvetrain runs - that may not help. The head screws are down the driver's side of the head and more or less in the "middle" of the casting, while you're dealing with the extreme right side.

Note my comments on head gaskets, above. If you've got a leak on the pax side deck, you've probably got a fully failed head gasket somehow, and you should just replace it outright. Note that there is no compression pressure and no oil pressure on that side of the head - just the crankcase internal pressure caused by blowby. The oil is draining back down that side under gravity (it gets pumped up inside the pushrods,) so if it's leaking at the cylinder head-engine block junction, the gasket is shot. There's as much pressure on that side of the head gasket as there is on the valve cover gasket.

Pull the head off, make sure it's not warped on that side, and check the block if time & equipment permit. Then install the new gasket.

The only other thing I can think of would be the CCV being plugged up, but I'd still be inclined to think the valve cover gasket would blow out first - not the head gasket. I could be wrong...

Yeah, I retorqued the head bolts when I did the valve cover a few months ago. CCV is clear as well. I started a new thread on this http://www.naxja.org/forum/showthread.php?p=244152479#post244152479. This could easily expand into an engine overhaul, so I might just cheap out and look for a low mileage replacement.