DUI dustributor problem

[77CJ7SC]

I have a DUI distributor in my 1977 Jeep CJ7 with a AMC 304 V8. Occasionally it will not crank and i have noticed that when this happens, there is a spot of oil on the rotor button. There is oil no where else in the cap. I can wipe this oil off with a rag, and it cranks right up. This is happening more and more often. The distributor is 2-3 years old. Do you know what the problem may be? Is it the oil from the coil? Any help that you could offer would be greatly appreciated.

 

[BusaDave9]

You say "it will not crank". That's a problem with the starter system and not the ignition. Battery terminals, starter solenoid, etc.

If it cranks and won't start then it could be the ignition system.
I would replace the cap and rotor

 

[77CJ7SC]

It turns over, but won't spark. I wipe the oil spot on the rotor button clean and it cranks right up. I don't have to change anything else.

 

[csuengr]

Sounds like the coil is going bad.

 

[77CJ7SC]

Can you replace just the coil on a DUI or does the entire thing need to be replaced?

 

[BusaDave9]

Yes, It's a HEI coil. you can get one at any parts store

 

[77CJ7SC]

UPDATE ! I replaced the coil, distributor cap, and the rotor with a new one. It ran good for a few days, but i am having the same problem today. It would not crank and i took the distributor cap off and found the same spot of oil on the rotor button. No oil anywhere else in the cap or around the rotor.
Any ideas?

 

[Torxhead]

I would think about tearing into that distributor and finding out how that oil got in there, like up through the shaft or down through the top, there must be some more in there.

 

[BusaDave9]

This is confusing. Originally I was thinking a PO used dielectric grease. By this point that's an impossibility. I also thought of engine oil but that has too far to go. It's also an impossibility that engine oil could get on TOP of the rotor but no where else. If engine oil was getting on top of the rotor it would also have to be splashed everywhere on it way up to the top of the distributor cap.

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This is very confusing. How much oil are we talking about? Can you tell if it is oil or grease?

 

[mtnwhlr]

I'm with you BusaDave, I thought maybe it was coming up from the motor but you are right it would be all over the dissy not just on top of the rotor but I don't know where else it could be comming from This is a tough one I can't wait to here the answer.

 

[Torxhead]

Well guys, I threw that one out because that is just about all I could think of. It is odd that one spot of oil lands on top of the rotor button like that and breaking the circut.

 

[77CJ7SC]

Its hard to tell. It looks like oil, but it could be a very thin grease.

When i took the old cap and coil apart, there was a fair amount of grease on the bottom side of the coil. Could it be that they come from the factory with the grease? Should i take the coil out of the new one and check it out?

 

[Torxhead]

http://jeepsunlimited.com/forums//showthread.php?t=443548

Here is a post from another forum on how to to use dielectric grease on an hei distributor.

 

[Les]

Ok, what I'm going to say may sound nuts, but here ya go.

While I've never head of this problem on a Jeep engine, I have heard of this problem in rare instances on various Japanese engines. In some import engines, you can have a blocked or partially blocked PCV valve, and this can have an effect on a distributor that has a weak o-ring shaft seal in it. What happens is that when the engine is running at temperature, it can cause a tiny bit of oil saturated, hot crankcase gas to be forced past the o-ring and introduced into the inside of the distributor cap. Once this vapor is inside there, it will tend to condense on the first surface it encounters which is cooler. Because of the heat transfer properties of carbon, or the lack thereof, compared to the other materials inside the distributor, the button will be the first place the oil ends up. It cools, condenses, and voila, you end up with a bit of oil on the top of your rotor. Since it is then fouling your ignition system, you never have the opportunity to run the engine long enough for any significant amount of oil to show up inside your cap.

Unless you find another reason for this oil being there, you might want to make sure your PCV valve is functioning properly, and if the problem doesn't go away after that, you can reseal the distributor shaft.

 

[77CJ7SC]

I'm a rookie at this, but i don't if i have a pcv valve. Isn't it usually on the valve cover? If not, can you tell me where it is and how to check it?

Thanks

 

[Les]

Yes, if you have a PCV valve, it should be somewhere on top of one of the valve covers. You will have a hose coming off of it and connecting to a fitting somewhere on the intake, although depending on the setup, it can be anywhere from the manifold to the carb, or on the air cleaner box. You might also not have the valve and just have a crankcase vent instead, which could be at least partially stopped up, and allowing pressure to build up inside your crankcase.

 

[CJ]

Crankcase ventilation system - Wikipedia, the free encyclopedia

 

[77CJ7SC]

I don't have anything on the valve covers, but here are a few pics of my setup.
I have what appears to be a vacuum hose that goes from my distributor to my carb. Is that it? If so, do i just remove the hose and make sure that it's clear?

Sent from my DROID RAZR using Tapatalk 2

 

[BusaDave9]

No that's for the vacuum advance.
The PVC valve on a AMC V8 is on the rear of the intake manifold.

 

[77CJ7SC]

I found it. It was hooked to the intake. I removed the hose and saw nothing in the hose itself or immediately around the connections.