Merc 260 Losing Oil

[greg82255]

Hello,

I have a 1986 Merc 260/Alpha One. The engine has about 770 hours on it and I bought it last October. I was told it was always dealer serviced. I changed the oil as part of winterizing last year and checked it at the beginning of the season, and it was full. I think it took about 5 quarts. Anyways, I have used the boat about 25 hours this summer and checked the oil yesterday and it was down more than a full quart. I immediately stopped using the boat until I got more oil. I put in a full quart and it still was not full. Is it normal to lose this much oil in this much time? or could I be leaking or burning oil? The bilge is clean and I don't see any oil, and I couldn't find any leaks when I looked around while it was running. Anyone know what might be going on here? Thanks in advance

 

[greg82255]

Re: Merc 260 Losing Oil

I don't have a compression tester but I am going to go out and get one today. Probably do the test tomorrow and post the numbers. If oil is being burned, any guesses as to what is happening? I should probably mention I haven't experienced any loss in power - then again, I just bought the boat in October so I don't know what it was like before I got it.

 

[jmorgan87]

Re: Merc 260 Losing Oil

burning oil is usually a sign of worn rings.

Does it smoke if ran on muffs?

 

[greg82255]

Re: Merc 260 Losing Oil

Does it smoke if ran on muffs?

It smokes a little. There was one point where I noticed a little more smoke than usual but that lasted about 30 seconds and then it went away. I can't really say I've been paying attention to the exhaust, but I'll take a look when I go out on it today. I have thru hull exhaust so I assume I should be able to see it coming out the pipes

 

[jmorgan87]

Re: Merc 260 Losing Oil

On cars, boat gurus please correct if different, worn rings depending how worn can smoke at different times.

On startup, from oil seeping down while the engine is not running.
when 'getting on it', a revving causes oil to get through and burn
if the rings are real worn out, it can smoke regularly.

Assuming these principles are same on a boat, i'd see if she smokes on a cold start. Then also a few revs on muffs and see if that causes a puff of smoke on each rev.

 

[scoflaw]

Re: Merc 260 Losing Oil

You could replace the valve seals, quick and easy, and see what happens. If that doesn't work, and you can't deal with adding oil, the fix is gonna get mighty expensive.

 

[greg82255]

Re: Merc 260 Losing Oil

Assuming these principles are same on a boat, i'd see if she smokes on a cold start. Then also a few revs on muffs and see if that causes a puff of smoke on each rev.

It definitely smokes alittle when I rev it out of gear. I'd say the smoke is white.

If that doesn't work, and you can't deal with adding oil, the fix is gonna get mighty expensive.

I can deal with adding oil, that's not a problem. If I have a problem that isn't going to go away and is probably going to get gradually worse (if the rings are worn), then I might as well rebuild it after the season is over. I want to build a new engine anyways but I couldn't justify spending the $ on something I don't need.

I think Bubba has it right. Going to do a compression test tomorrow, and that should tell me for sure what's going on.

 

[jmorgan87]

Re: Merc 260 Losing Oil

err, I made a mistake...not big since you said smoke during reving..but smoke on a cold start can also be valve stem seals. Basically if it only smokes at start, and not during reving or normal use it could just be valve stem seals... correct me if I am wrong please.