OMC 2.5L milky oil after short time

[iflyboats]

I have good news!

Got the engine in the driveway, ran it for 5-10 minutes hooked up to water. So far so good! Ran decent considering there was no carb gasket, and no signs of water or fuel in oil! Got the temp up to about 130 or so, but it started snowing pretty good and I wanted to get everything back inside.

Pulled the riser off immediately after, no signs of water in exhaust - still going to replace the manifold though on account of all the exterior cracks - I just don't trust it.

One bit of bad news though - my rear main seal is leaking pretty badly. Is this changeable by just pulling the oil pan, or does the bell housing have to come off? When I pulled the engine I tried to remove the intermediate housing, but I just could not get the sealant to bust loose after beating on it with a deadblow for half an hour.

 

[iflyboats]

Now I'm just confused by that rear main seal leak.

Ran the engine again for ~20 minutes. Rear main is literally pissing oil. Weird thing is...the oil dripping from the bell housing is very milky, but the oil on the dipstick is still clean. Is there some sort of water passage near the rear main seal that could be mixing on its way out? Or is this block just FUBAR...

 

[iflyboats]

Took off the flywheel cover to get a better look at the oil coming out. Not as milky as I thought, caught some on paper and its the same color as what's in the pan (still has a tiiiiiny bit of white color to it, I've changed the oil twice but can't pump out the last little bit in the bottom of the pan).

 

[iflyboats]

Found source of leaking rear main seal - crankshaft had a bit of rust on the sealing surface. Cleaned the shaft up and put in a new seal, no more leaks! Also took the opportunity to clean out the oil pan - had about an inch of standing miky oil that couldn't be pumped out through the drain tube. Oil now looks nice and clean after running.

I also checked out the distributor rotor & cap, set the breaker point gap and set the timing. Also rebuilt the carb. It runs pretty reasonably well but has an occasional stumble when revved up at a constant speed. Idles great, accelerates great, but holding at (guessing, can't see the tach with the engine in the driveway) around 2k-3k rpms, it seems to have an intermittent stumble/miss. Is this somewhat normal for a marine engine designed to be under load? I figure the carb is setup for when the prop is in the water, and maybe it's a bit rich or lean with no load on it. Any ideas here?

 

[PITBoat]

You may have mentioned it earlier, but plugs and wires? I've found bad plug wires before by checking the resistance.

I'd think if it's missing in N, it wouldn't be any better under load, or maybe worse, depending on the cause. I've had some stumbling or missing from mine, that has smoothed out nicely after just cruising a while. Using the boat regularly helps too.

 

[kenny nunez]

Take a look at the rotor shaft to see how much the shaft can be moved against the points. There is a good chance that the distributor is worn. The bushing in the block wears and the causes the points to not hold a steady gap which effects the timing to also not hold.
Also remove the breaker plate and inspect the counter weights and springs, sometimes the pins that support the weights and springs loosen up.

 

[iflyboats]

I'll take a look at that distributor shaft. I took a look at the counterweights etc already, everything seemed in order there.

I don't think it's really a miss - it sounds more like a burble from being too rich. I've tuned plenty of motorcycle carbs, but those are easy - just move a clip on the needle and all is done. Not sure if I need to swap out the main jets, or maybe the ratio would actually be perfect when under load but with no load it's just too rich. If the boat itself was seaworthy yet I'd just go take it out and find out!