What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

distributer leaking oil

bp71k5

bp71k5

3/4 ton status
Joined
Mar 31, 2006
Posts
8,840
Reaction score
2,833
Location
Knoxville, TN 37922
I've been trying to track down a pretty serious oil leak for a while now and I've finally tracked it down to the tbi distributer I bought new.

The leak is serious enough that after I've degreased and cleaned the engine and dried it off, it takes about 2 miles of driving before I can see oil weeping out from under the distributer cap.

In this picture, the green arrow is pointing to the nice colored motor oil pool.

Any ideas on how to fix this? I didn't know oil even got up that far.

distributer leak.jpg
 
Make sure the PCV system is working properly. Also did the distributor have both O-rings on the housing before you installed it? The O-rings aren't what are causing this issue but i was just checking to make sure they're on there.

Too much crankcase pressure is what is causing your current issue and that can happen from the PCV system not functioning properly.
 
I have no idea whether there's any orings on it. I should check obviously. The PCV system is working as far as I know. Is there any foolproof way to confirm? Could I take a vaccum reading on the throttle body port?

Does oil somehow travel up inside the distributer? I don't understand how it's getting up there. I would expect it to leak out of the crankcase from the hole in the intake manifold.
 
PCV valve is sucking quite well. I put my finger over it and the engine speed change slightly and I feel a strong vaccum. The valve isn't a super tight fit in the rubber o-ring that's on the valve cover so I could try replacing that but it doesn't look like that's the problem.

Also, I need to pull the distribtuer, but I'm almost positive there's no o-rings except for the gasket that goes between the shaft and the intake manifold. None of the pictures I have show any other o-rings.
 
You should have a PCV valve in one valve cover and a clean air tube in the other that goes to the bottom of the air cleaner.

It looks like that is an MSD distributor which uses O-rings on the housing just above and below the oil galleys for the lifters.
 
You should have a PCV valve in one valve cover and a clean air tube in the other that goes to the bottom of the air cleaner.
Click to expand...
Here's what I got. First pic is the PCV vale and line to the tbi and the other is the breather hose piped into a port below the air cleaner.

It looks like that is an MSD distributor which uses O-rings on the housing just above and below the oil galleys for the lifters.
Click to expand...

I bought it pretty cheap from ebay with no mention of MSD on it or the auction ad. It just said these were a "closeout" type deal. Is there a seal somewhere inside the distributer that could have gone bad or do you really think I've got a crankcase pressure issue? It doesn't seem to leak if it's just idling, but the second a drive it even a mile and then look up there from underneath, there's more than a few drops of oil coming from inside the distributor cap.

pcv 001.jpg

pcv 002.jpg
 
I had an MSD distibuter do that, I called them and they sent me a little seal and it fixed it. it went down inside the distributer shaft, not on the outside.
 
I'm pretty sure it's not MSD after comparing some pictures. Do you happen to have a part number for that seal or know where to get it?
 
does that breather have vents around or on the bottom of it..the round piece on valve cover w/hose to breather base..is that a vent or is it a sealed container making a 90* turn?
 
blazin_blazer said:
does that breather have vents around or on the bottom of it..the round piece on valve cover w/hose to breather base..is that a vent or is it a sealed container making a 90* turn?
Click to expand...

It doesn't have vents on the outside, but it's supposed to be open from the hose fitting into the valve cover. I didn't actually confirm that though. I will now check it and make sure though.

This distributor no markings on it, but it does look like it's a billet aluminum style with the o-ring grooves for the oil galleys. No o-rings are installed on it though. Looking through the MSD brochure, they have this feature but you need to chamfer something inside the block to use the o-rings.

I dunno, my $50 brand new distributor is not looking like such a great deal anymore...
 
I checked the breather and it's open with a sponge inside. I assume that's to keep oil from splashing up through it.

I also disassembled the distributor and found nothing that looks worn out. It looks like the oil is being pushed up through the center shaft.

I'm now back to wondering about the PCV system even though it appears to be setup correctly.

Edit: This is a long shot, but my PCV valve is for an 89 350/v8 and my motor is technically a 71 350/v8. The valves for those years appear to be different.
 
i think that breather being open is your problem & would/could make it run lean and allow the pcv circuit to be ''open'' i do believe it should be a closed loop system from what i've heard 4x4high talk about the pcv workings. surely he will ring in and give us the scoop....if that breather is sucking outside air and not pulling vacuum on the crankcase, you may actually be having a positive crankcase pressure & the hose from the breather base that goes into a breather that is open to atmosphere, it could suck outside air there and act just like a vacuum leak.

4x4high would it hurt to run a pcv on both valve covers? i think replacing that breather w/a 2nd pcv valve will stop you from losing vacuum by keeping it from sucking outside air threw the foam in the holes i asked about, instead of pulling vacuum on the crank case, like it should be doing and this may help cure your troubles

edit: no 2 pcv valves would fight each other since they work as check valves, you need a 90* elbow from valve cover to hose w/o any holes in it instead of breather...i think it would be worth a try
 
Last edited:
blazin_blazer said:
i think that breather being open is your problem & would/could make it run lean and allow the pcv circuit to be ''open'' i do believe it should be a closed loop system from what i've heard 4x4high talk about the pcv workings. surely he will ring in and give us the scoop....if that breather is sucking outside air and not pulling vacuum on the crankcase, you may actually be having a positive crankcase pressure & the hose from the breather base that goes into a breather that is open to atmosphere, it could suck outside air there and act just like a vacuum leak.

4x4high would it hurt to run a pcv on both valve covers? i think replacing that breather w/a 2nd pcv valve will stop you from losing vacuum by keeping it from sucking outside air threw the foam in the holes i asked about, instead of pulling vacuum on the crank case, like it should be doing and this may help cure your troubles

edit: no 2 pcv valves would fight each other since they work as check valves, you need a 90* elbow from valve cover to hose w/o any holes in it instead of breather...i think it would be worth a try
Click to expand...

This is exactly how the system should be. That breather with the holes on the bottom isn't allowing the PCV valve to do it's job properly. There iscrankcase pressure building up and it will push oil out the easiest place first then start blowing all kinds of other seals/gaskets soon after.

There is a "breather" just like the one you have but without the holes.
 
Just to be clear, the round canister on the passenger valve cover does not have holes to the outside. The only hole through it is the big one for the hose that attached. It just has foam inside to filter the air before it gets into the crankcase.
 
bp71k5 said:
Just to be clear, the round canister on the passenger valve cover does not have holes to the outside. The only hole through it is the big one for the hose that attached. It just has foam inside to filter the air before it gets into the crankcase.
Click to expand...

I thought you said a couple posts up that there were holes in it? If there are no external visible holes and the only hole is for the hose then that is the correct "breather" and you either have extreme crankcase pressure building up OR the PCV valve isn't working correctly (PCV valves are cheap and i would replace it) also make sure the hose on the PCV and breather for that matter is the correct hose, you cannot use standard rubber hose as oil will attack it and make the hose squish closed under certain conditions then the PCV system can't function properly.
 
4X4HIGH said:
I thought you said a couple posts up that there were holes in it?
Click to expand...

Maybe there was some confusion, but blazin-blazer asked about the holes and I attempted to replay there wasn't any.

I'll replace the pcv valve and reassemble my distributor and try again.
 
I replaced the pcv valve with the part number for a 71 instead of an 89 like I had before. The suction on the end of the valve while the engine is running is noticably stronger. I don't know if the old valve went bad after 3000 miles, or the later style doesnt allow as much suction but so far no more oil leaking from the distributor. I still need to do a more long term test but it's good so far. Yipee!
 
Greg72 said:
Blame it on the engine builder....that's what I'd do! :D


:usaflag:
Click to expand...

You're a funny guy there Greg. :rolleyes:

Brian, do a compression check and post the results. With the detonation you've been having you may have broken some rings and or piston ring lands and are now getting excessive blowby which is resulting in the PCV system not being able to remove the vapors quick enough which is causing your leaks. If this is the case then unfortunately it would mean pulling the heads and pistons and replacing the rings (assuming you don't have any broken pistons). I know this isn't the news you want to hear but detonation that is left unfixed causes bad, very bad things to happen.
 
You must log in or register to reply here.

Latest Posts

Top Bottom