Merc 502 spitting oil
 

I Finnaly moved from Cruisers to a performance boat. I took my new to me 312 Formula out yesterday for a test run. Everything on the gauges looked fine all day even at several WOT stretches. When we returned the front part of the motors had dropped a small amount of oil into the bilge. How concerned should I be about this? I have heard the 502's burn oil, but didn't think they spit it out. These motors are 98 models, look clean (whatever that's worth), and have 380 hrs.
I guess I'll need to post some pics of a new members boat sometime too!

Re: Merc 502 spitting oil
 

It's good to hear that you finally got it home!!!! :D

If it's just a small amount, it's possible that it's coming out of your trim pumps. Get some leak-proof caps from turbosonic.

Re: Merc 502 spitting oil
 

Both engines had the same oil leak? Did any of the belts or pulleys whip the oil around to the underside of the engine hatch?

Re: Merc 502 spitting oil
 

Gotta know where its coming from. Might be a big deal. Might not.

Re: Merc 502 spitting oil
 

Thanks guys!
When I got home last night it was dark, I'll go dig around now and be back in a little while.

Re: Merc 502 spitting oil
 

ok....I see where the oil is coming from. It's the same from both motors. It appears to be the front seal behind the timing belt? The lower center pulley that has the timing marks on the disk behind it right?[IMG]http://[/IMG]
I'm attepting to attach the photos of the motors, hopefully they help.
Thanks again.

Re: Merc 502 spitting oil
 

I am trying to figure out what kind of oil leak at the front of the engine could be a big deal. Should be either timing cover seal, oil pan seal or front intake seal. Maybe I missed something... Please enlighten.

BT

Re: Merc 502 spitting oil
 

Front crank snout seal isn't a big deal (there's no timing belt, it uses a chain unless it has a massivley expensive aftermarket Jesel drive). It's a little odd, though, that they're leaking unless the motors have been into a few times (without new seals each time).

Easy to replace.
It MAY however, be an indicator of a worn front main bearing due to possibly having had a previously installed supercharger on the motor before you bought it. If that is the case, you could have some other issues as well.

Re: Merc 502 spitting oil
 

For some reason I don't think anything aftermarket has been done to these motors. Sorry about the timing belt comment... I meant chain. I am a novice though obviously. I just dropped the thing off with my mechanic to check out a number of things, this just got added to the list.

Re: Merc 502 spitting oil
 

testing downloading photos.....These were supposed to be in an earlier message.
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If there are no photos here, what am I doing wrong?

Re: Merc 502 spitting oil
 

Is it dripping from behind the harmonic balancer or is the oil dripping from inside of the front pulley??????
My factory sealed 525sc dripped out the center of the pulley. It barely dripped, but when it was running, it would spray little drops all over.
If its just dripping and not getting flung around, then it probably the oil pan seal.

Re: Merc 502 spitting oil
 

Good point. If the damper has ever been removed (or sometimes if it hasn't), there can be oil creeping thru the bore of the damper and coming out behind the flange washer.

Re: Merc 502 spitting oil
 

Its common practice (or should be) to use some Ultraseal behind washer and bolt for the harmonic balancer. The oil can leak through the keyway slot in the balancer. Easy fix if that is where its coming from.

Re: Merc 502 spitting oil
 

Thats not unusual for these motors. If nothing else was touched before this is most likely where its coming from. I have replaced a couple of vibration dampers with fluidamprs and noticed oil seeping from around the bore on more than one motor.

Re: Merc 502 spitting oil
 

I'm not sure what the "harmonic balancer" is. The lower center pulley has a disk behind it that has the timing marks on it (Is that the Harmonic balancer?) Anyway if I reach behind that disk to it's center, I get oil on my finger tips. Look at the center of my 2nd pic. Oil dripped out and did not get slung anywhere else in the bilge. Each engine lost approx a tablespoon over 2 hr run at RPM's from 3500 to 4000 with a few minutes of 5,000 RPM's.

Re: Merc 502 spitting oil
 

That disk with the timing marks is the balancer. It sounds like the oil is seeping through just enough to be an annoyance. I would monitor it if you are still running the boat and if you are not using it, take the lower pulley and damper off. You will gain access to the front seal and you will have a much clearer view of the timing chain cover and any other possible areas for the oil to leak out. That isn't a bad project to do. You will need a damper puller, a torque wrench, and definitely some Ultraseal like Formula31 mentioned.

Re: Merc 502 spitting oil
 

If its not getting slung around and its behind the the harmonic balancer(yes, thats the disc with the timing marks :D ), then the timing cover gasket is probably leaking in the corners or where it meets the oil pan. It's a pain in the a$$ to get them resealed completely once they are removed.

Re: Merc 502 spitting oil
 

If you pull the balancer check the snout for a groove cut into it from the front seal. It always amazes me that a rubber seal can groove a steel part. Anyway it to is an easy fix. They make a sleeve that goes over the balancer snout and then replace the seal in the timing chain cover. Good luck.

Re: Merc 502 spitting oil
 

Thanks for the feedback.....
My mechanic says the material cost in a non-issue, but the job should take aprox 2 hours per motor....On the plus side, he is only charging me $50.00 per hour. Should I just do it, or wait and see how bad the leak gets in the spring?

Re: Merc 502 spitting oil
 

Do it Now! While the boat's "down". That's what winter's for. (Only thing I can figure) It won't fix itself and it could make a big mess of your boat, ruin a day or weekend, and still have to be fixed.