1993 Mercruiser 3.0 distributor leaking oil.

[Blueheeler]

After a 40 mile trip today i pulled the engine cover to look things over and noticed oil on top of the fuel pump so i looked all around and everything appeared dry so after some head scratching as there is nothing above the fuel pump i started feeling around and then found a significant amount of oil on the distributor underneath the cap and rotor plate. Seems like a odd place for a oil leak. Any ideas?

 

[alldodge]

The gasket (item 14) is either damaged or missing
https://www.mercruiserparts.com/bam/subassembly/30914/1604/80

 

[Blueheeler]

The distributor i have looks different than the one listed above. According to the parts book it is a EST unit. I checked the area around where the distributor meets the engine and it is dry it looks like it is coming from inside the distributor as there is oil on the plate where the cap bolts onto. Is it possible for these to leak from inside out?

 

[alldodge]

Your motor can have 1 of 3 distributors but all use the same gasket

Are you seeing any oil up by the valve cover?
After motor is warmed up remove the oil cap and see if there is any blowby

Remove the distributor cap and wiggle the rotor side to side. If its worn and there is some blow by it could be coming up the shaft

 

[Blueheeler]

There is a small amount of blow by as i can see a light film on my air breather where the hose aims toward it. I am going to go out and check the shaft for wobble here in a few min ill let you know my findings.

 

[Blueheeler]

The shaft has no play in it but there is clearly oil inside the unit. I called a distributor rebuilder and he said these units just have a bushing in them with no seal and that this is almost always caused by excessive crankcase pressures due to blow by. This motor has 140 psi across all cylinders and does have blow by as seen by the oil film by my flame arrestor. I then called the local boat shop and he told me to put a rag down or spend 4k to rebuild the motor. Seems dumb to me to design a short shaft distributor with no internal seal on a motor that turns 3500-4500 all day long. He suggested adding a PCV and a vented oil filler cap to reduce pressure but there is no port on the carb or intake manifold for this application. The motor runs great all day long so im not going to rebuild it at this time. hopefully this will not ruin the module in my distributor.

 

[Blueheeler]

[No message]

 

[Blueheeler]

[No message]

 

[alldodge]

Agree, but just run a hose from the valve cover into a quart bottle from the valve cover. The bottle will collect the oil and let excess vapor escape

 

[Blueheeler]

Ok ill give that a try and see what happens.

 

[Blueheeler]

All dodge.I am going to the auto parts to pick up a hose for a catch can. While i am there a am thinking of picking up a spare module and pickup in case of failure on the water. I had several cars in the late 80s and early 90s with these same distributors. The est distributor module in the marine catalog shows it works for 4 6 and 8 cylinder models so if this is the case how is the timing advance differentiated between these motors with the same module? I do not see any type of mechanical advance or am i missing something?

 

[Blueheeler]

I guess im trying to figure out how the module

​can take my 3.0 engine from 0 BTDC to 24 BTDC (24 deg. advance) but a 5.7 is 8-28 degrees of advance advance. How does it know to advance the different engines different amounts? Curious on any thoughts as i can pick up a spare at the auto parts store for much less than a marine branded unit that is physically identical.

 

[alldodge]

All EST advance are 24 give or take a degree. This is why the 3.0 is set at 1 ATDC. The EST wasn't used on V8 until EFI was also introduced. Depending on the year the V8 could have EST or TBV with MEFI ECM

The EST module and the magnetic pulse generator in the distributor is all the is used to control spark timing