2001 Merc 50hp 2 stroke..rebuild or take the risk??

[pilot0677]

Hello everyone...

New to the forums. Ok here's my situation. Bought a 2001 Odyssey pontoon. Boat in great shape and engine is very clean. Bought this from a marina that was storing it for a guy, winterizing, etc. They told me they went though the engine and everything was great. Trusted them, and that was my first mistake. Didn't run compressions. Sounded great out of the water on the muffs. They delivered the boat, got it in the water and heard a slight 'ticking'. Took it to the mechanic and he ran the compressions 130-90-120. Said there was a knock and need to rebuild. Wants to replace the powerhead with a Merc. powerhead for around $2500+800 install. Looks like I may be better off getting a used motor with more horsepower for that! Motor runs pretty good when warm. Starts up cold with choke and idle lever extended. Has great power at top end. It will stall sporadically when tooling around the lake, but it seems like its only when it's cold. I put a can of seafoam in about 5 gallons so far. Should I change the plugs? The guy I bought it from gave me $500 back in 'good will' for the rebuild. So I need your help...do i get this rebuilt right away? do i try to make it through summer? do i just get a different engine and sell this one as is? or do i not worry about it? It's a 2001 50hp 2 stroke...seems so premature! All of your help would be appreciated!

 

[pilot0677]

Re: 2001 Merc 50hp 2 stroke..rebuild or take the risk??

Oh yea,

Could I just change the one bad piston/cylinder/wrist pin, rod, etc? Or do I have to reman the entire engine? Should I just run it till it blows up? Is 90 lbs really bad compression? Could this just be stuck rings? I am tempted to pour seafoam in the cylinder and let it sit over night...I just need some advice...

Thanks,

Kal

 

[pilot0677]

Re: 2001 Merc 50hp 2 stroke..rebuild or take the risk??

Any help would be appreciated...

 

[dgengineer]

Re: 2001 Merc 50hp 2 stroke..rebuild or take the risk??

I'd be very carefull. Firstly, I wouldn't run it until it blows up. You may lose your core & not have anything left to rebuild. I would try to loosen up the rings first; confirm the results with a compression test before making a decision to run out the season or rebuild. I wouldn't run an engine with more than a 10% difference in compression readings between cylinders; it's asking for catstrophic failure. If loosening the rings doesn't help, I would be inclined to rebuild the power head completely. On a 2001 engine, it makes sense. partial rebuilds dont make sense because of all the labor to remove and reinstall the powerhead.

 

[hotrod53]

Re: 2001 Merc 50hp 2 stroke..rebuild or take the risk??

I was told about a product by a former marine repair owner called Ring Free, he claims that it is the best stuff on the market and that you will actually see carbon blowing out. Unfortunately I have been unable to find this stuff anywhere, but he claims that if you have a stuck ring, this will free it in one shot. It seems odd that a motor that new would have 1 worn cylinder when there's old motors from the 70's out there still going strong. But I guess it's what everyone tells me, boats = $$$

Anyone care to comment on what this stuff is and where it can be found?

 

[Faztbullet]

Re: 2001 Merc 50hp 2 stroke..rebuild or take the risk??

This model engine in the 50 & 60 hp are bad about the sleeves slipping in them. On a toon the engine has greater chance of this happening as its working it guts out at wot. You can rebuild it cheaper but have the sleeves pinned in place before assembling. I do this to all my rebuilds of these models.

 

[pilot0677]

Re: 2001 Merc 50hp 2 stroke..rebuild or take the risk??

Well thanks for the input so far! I have been running the boat this season, so far so good. I can only hear the knock at idle. It doesn't seem to get louder with higher RPMs. Boat starts up right away. I have to choke and advance the throttle to get it to fire, but it fires after about three or four seconds from being stone cold. Idles great. Great power at WOT. Doesn't bog in all power bands. I am having a bit of a problem with the primer bulb going soft, so I think I may have an air leak in the fuel lines? If I don't pump the bulb, it'll stall after about five or ten minutes of running. If I pump the bulb when it start to stall, it'll come back to life right away and run great. I'm thinking this may be the problem with the center cylinder (running lean from fuel starvation in the past??) Could this be the fuel pump or should I replace the primer bulb and fuel lines?

I have to say that I am always worried about the engine blowing up though? Not sure how bad 90 PSI in the center cylinder is really. A lot of guys from the lake keep telling me not to worry about and and keep running it...I am questioning the mechanic now about the compression readings and am debating whether I should take some readings myself. Maybe it's something under the flywheel? I just don't understand how it runs so great with the mechanic telling me how 'bad' it is??

Thanks for the input!!

 

[matth121]

Re: 2001 Merc 50hp 2 stroke..rebuild or take the risk??

i might be just talking out my arse here, but definitely run your own compression test. I may be lucky in the fact that i have a mechanic as a friend so was able to just grab his tester and run my own tests, but it'd be worth $20 to get someone to do it, while you watch.... the rings that may have been stuck might have freed up with you running it. Definitely time for a new test. Also, a full rebuild would cost less than the $3300 your dealership wants to charge- way less if you do it yourself. Get a manual man, you can do it, lol
matt