Chevy EFI small cap distributor oil leak

[Learpilot]

I have a problem with an aftermarket Chevy Small cap distributor leaking oil up through the shaft. The star wheel is wet with oil and it leaks out of the bottom of the distributor cap. This distributor is not  GM made. It looks like it has a place for two o-rings above and below a small hole on the bottom just above the gear.. There is a large hole on the shaft about a 1/3 way up. I think it has a bearing on the bottom instead of a bushing, it spins freely. If it is supposed to have o-rings, what size ? Also is there a seal that could be bad that is letting oil through ?
Thanks in advance !!!
Rick Harris

[wayne petty]

just a thought....

is the pcv valve working good and the breather vent in the other valve cover instact??

i have had a bunch of dizzys apart and there are no seals on teh shaft .. sometimes there is a clear plastic cover over the vent.   but the vent usually has some felt and is a wick.....

any printing on it???   msd, accel, pertronics, crane, mallory,

fyi for people tearing down small cap dizzys

warning ...   when disassembling a small cap chevy distrubuter.. be really sure to drive the roll pin out with full support rigid support under the gear end.. to much impact with a hammer  rocking the entire housing may crack the ceramic magnet  that is riveted into a sandwitch that becomes the reluctor on the dizzy shaft...  when these magnets break the parts are trapped and cause weird misfiring... ac delco used to sell the shafts separate..like 25 cocos... the only aftermarket shaft was over 125 cocos... and that was probably a reboxed delco....fyi.....

[Learpilot]

just a thought....

is the pcv valve working good and the breather vent in the other valve cover instact??

i have had a bunch of dizzys apart and there are no seals on teh shaft .. sometimes there is a clear plastic cover over the vent.   but the vent usually has some felt and is a wick.....

any printing on it???   msd, accel, pertronics, crane, mallory,

fyi for people tearing down small cap dizzys

warning ...   when disassembling a small cap chevy distrubuter.. be really sure to drive the roll pin out with full support rigid support under the gear end.. to much impact with a hammer  rocking the entire housing may crack the ceramic magnet  that is riveted into a sandwitch that becomes the reluctor on the dizzy shaft...  when these magnets break the parts are trapped and cause weird misfiring... ac delco used to sell the shafts separate..like 25 cocos... the only aftermarket shaft was over 125 cocos... and that was probably a reboxed delco....fyi.....

Everything is A-OK with the rest of the engine. I borrowed a stock Small cap Distributor in just to test to see if it stop leaking and it did not leak. I would like to get this one to stop leaking oil, but if not I can always get a stock one. I got this distributor with the EFI system and before I blame a bad distributor I want to make sure I have done everything right. I still don't know it it needs o-rings on the bottom.  
Thanks, Rick Harris

[Charlie Chops 1940]

Something is not right with this engine.

I'm not sure what the o-rings would be sealing since the area just above the drive gear is in the same atmosphere as the  area above the upper o-ring and the interior of the housing is also in that atmosphere. Unless something is pressurizing the inside of the engine, and in turn the dist. housing, oil shouldn't be coming up through the dist. I think that was the gist of Wayne's question about the condition of the crankcase ventilation system.

Gravity makes the oil drain into the pan and crankcase pressure above  outside atmosphere pushes oil out through the most innocent appearing fissures. If nothing else has changed and the OE dist. doesn't leak then there is indeed something different inside your old dist that forces oil out the top of it.

I've never seen a Chevy dist. with o-rings on the bottom. I'm not sure what the answer is but I suspect its inside the dist. and maybe related to some malfunction in the PCV system.

Of course I could also be completely wrong....

Charlie

[Bob C]

Way too much crank case preasure.
Bob

[Learpilot]

Something is not right with this engine.

I'm not sure what the o-rings would be sealing since the area just above the drive gear is in the same atmosphere as the  area above the upper o-ring and the interior of the housing is also in that atmosphere. Unless something is pressurizing the inside of the engine, and in turn the dist. housing, oil shouldn't be coming up through the dist. I think that was the gist of Wayne's question about the condition of the crankcase ventilation system.

Gravity makes the oil drain into the pan and crankcase pressure above  outside atmosphere pushes oil out through the most innocent appearing fissures. If nothing else has changed and the OE dist. doesn't leak then there is indeed something different inside your old dist that forces oil out the top of it.

I've never seen a Chevy dist. with o-rings on the bottom. I'm not sure what the answer is but I suspect its inside the dist. and maybe related to some malfunction in the PCV system.

Of course I could also be completely wrong....

Charlie

This distributor is a billit type with a bearing in the bottom not a bushing like a stock one. I was told by my friend that loaned me the stock distirbutor that the area between the two o-rings is pressured by the engine oil system. There is a small hole in the area between the two boss that look like they need an o-ring. This distributors look like the ones that are sold on EBAY for about $50.00. I would bet these are made in China, but am not sure. I just want to stop the oil leak. The back of the block is dry when I use the stock type distributor.
Thanks , Rick Harris
ps I will go to ebay and get the number so you can see the same type of distributor I have.

[tomslik]

msd uses 2 o-rings but i leave the bottom one off (thinking that more oil on the cam/dist gears won't hurt a thing BUT i'm thinking too much crankcase pressure....

[Anonymous]

I made the mistake of purchasing one of those no-name $50 electronic distributors for my Chevy truck off of ebay.  Oil leaks into the top part of the distributor and runs out the little screen vent on the baseplate.  It also has a wierd intermittent miss at 2000-2600 RPM but im not 100% sure its the distributor yet.

It didn't leak with the old stock distributor so its not a crankcase pressure problem.

Has anybody discovered a leak fix for these cheap distributors? Did i demonstrate the old adage: You get what you pay for?

[Anonymous]

Problem resolved on my truck!
The oil leak was most likely my fault. In diagnosing the other problem, i ran RPMs up with air cleaner removed and PCV valve stopping pressure relief for a few minutes. PCV system hose draws vacum above the throttle body so there was a buildup of crankcase pressure - DOH!  I'll check for oil inside distributor after a few days of use to be sure.

The strange RPM-specific miss is gone after changing out the distributor module with my old one. I did notice one of the pin connectors inside the distributor was loose. I gently squeezed the female together so it is tight on the replaced module. The ebay unit either had a bad module or loose connector.