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Oil pouring from distributor mount...

Runnin'OnEmpty

NAXJA Forum User
Location
Southeast USA
It's a 96 4.0 XJ with a new Omix-Ada distributor installed
a few months ago. Since then I've been searching for the
source of a huge oil leak; should have suspected the dist
but I did install a gasket with it and thought I did a good
job.

After a 5 mile drive today I immediately popped the hood
and felt around the dist base and it was wet with oil. I can't
see the distributor mount but I can feel the oil. Couldn't
believe that much oil could come from the distributor...?

The supplied gasket for the new distributor was very thin.
I plan to cut a new one out of thicker gasket material and
install it using a gasket sealer.

Could the new distributor be hanging on something and
not be mounted flush to the block?

Thanks for any ideas.
 
Its is a very thin gasket for it, I never had a problem when I did one. Since its right next to the oil filter adapter, and those are known leak points, are you positive its from the dizzy and not the o-rings right there?
 
did you get the oil pump slot aligned with the tang on the dist?
I thought I did. The slot was slightly out of place and I
moved it with a screwdriver to get the dist shaft to engage.
The old dist shaft had wear marks on each end of the tang,
like it was a loose fit, but I guess that's normal for this engine...? The oil pressure is the same as with the old dist.

Foxwar71 said:
Its is a very thin gasket for it, I never had a problem when I did one. Since its right next to the oil filter adapter, and those are known leak points, are you positive its from the dizzy and not the o-rings right there?
At first I suspected the filter adapter, and looked at it
very closely, but it was always dry. The oil is definitely
coming from the dist base. It is wet with oil and draining
down on the front axle, oil pan, etc. I never thought this
much oil could come out there. That's what made me
think it must not be seated correctly.

Thanks for the replies. I'll know more when I pull the
dist again, maybe tomorrow.
 
Check the small vent tube (CCV) that comes out of the rear half of the valve cover. Blow through where it mounts into the valve cover, blow through the tube and blow where the vacuum nipple is on the intake. I've had both ends and the tube itself get mostly clogged.
 
Do you still have the old distributor?
Perhaps the tang is slightly longer, and will not allow the distributor to seat fully.

If you have oil pressure, then it was engaged as the cam drives the distributor which then drives the oil pump
 
Thanks for the tips guys, both good ideas.

I found the source of the leak, and you'll never believe it.

The distributor casting is a hold-over from the old days
of the AMC 258 engine, which had an oiling tube sticking
out of the distributor base and turning upward with a
spring cap on the end. (You old-timers know what I'm
talking about.) The distributor top bushing could be oiled
through this tube using a squirt type oil can.

The newer distributors have this hole plugged.
The hole was open in the Omix-ada distributor I had installed recently, and this was where the oil was coming out. So I'll pull the distributor again, tap the hole and plug
it. (It's a 1/4" hole.)

For anyone replacing their distributor, pay special attention
that this hole is indeed plugged...Thank you Omix-ada.

And thanks for everyone's help, appreciate the replies.
 
The shaft inside the distributor have a spiral grove cut into it to act as an oil slinger i.e. to push the oil back down as the shaft spins. They are cut in the opposite rotation to that of the shaft. outside of that, there is no seal inside the distributor itself. If the shaft is worn or worn bushings (I do not remember if there is bushings inside the distributor) in the distributor body it will be possible to get oil inside the body of the distributor. That may not be the issue in your case but it may be worth looking at.
 
The single biggest reason for a distributor leaking has nothing to do with a gasket. It has to do with pressure buildup in the crankcase.

This is normally cause by a plugged CCV tube, but it can be made worse by worn valve guides or shot compression rings. If the tube is plugged, you can clean it or they are quite cheap at the dealer. The last time I checked, they were less than $20 and there are aftermarket items as well. IIRC Napa has them.

You can prove this to yourself easily. Start it up and drive it like before, but loosen or remove the oil filler cap. If it is pressure buildup, it will go away when the cap is open.
 
Wow, I'm learning a lot about these XJ distributors and oil
leaks. Thanks for the replies.

I'm sure the source of the leak is the open port in the dist
base, since there was no leak before replacing the dist.
But it might be leaking more because of a partially clogged
CCV. I removed the rear tube and blew into it; it was open
but don't know if it was completely clear or not. I'll remove
it and check again once the distributor is back in. This will
also give me a chance to see if oil is actually inside the
distributor housing.
 
Finally had a chance to pull the distributor, and I was wrong
about the port in the side, it did have a plug in it from the
rebuilder. So the oil leak is coming from the gasket area
where the dist meets with the block.

I did notice something strange. When the dist is fully seated it is easy to turn when holding downward pressure
on it. It's almost like the dist shaft is bottoming on the oil
pump drive, and there's very little friction between the dist
gasket and the block. After removing the dist, I measured
the shaft length from the base to the end, and from the
cam gear to the base, and the measurements were within
1/32" compared to the old distributor. Close enough for
Government work.

So my fix was to double up on the gaskets along with adding a coat of gasket sealant. Also pulled the CCV hoses and they looked clear. The air filter was clean, and the XJ only has 64K miles so no blowby. I'll post back the results after a few days of driving....
 
Thinking back, that's what I should have done.

I assume yours was leaking oil too, and that's how
you found the shaft was too long?
 
Had the same problem with a rebuilt. I caught it upon installation. I ground the end of the dizzy shaft down about 1/8".
I got to thinking about your post, and pulled the distributor
again. Looked into the engine with a flashlight and the oil
pump drive slot appeared to have tapered sides, sorta
like a slot for a screwdriver. The distributor shaft tang has
flat sides, and the Omix-Ada tang seemed to be slightly
wider than the stock dist tang. So I filed the Omix-Ada tang
on both sides, in the shape of a screwdriver head, very
slightly. Figured this would give a better fit if indeed the
shaft tang was binding in the oil pump drive slot.

Then I installed the dist...again...using two gaskets. After
about 15 miles of driving today, no leaks. The paper placed
underneath the XJ is completely dry, and I can't feel any
oil at the distributor base. It's probably fixed, but a few
more miles will tell for sure.
Thanks again for all the help.
 
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