2002 merc 25 motor seized after being laid on side for years

[jbjennings]

Re: 2002 merc 25 motor seized after being laid on side for years

If you determine it is the powerhead, I'd go ahead and tear it down. Too many things can be causing the stuck-ness to chance it otherwise. As new as it is (by my standards) it's worth putting some time and money into it to make it right.

I'd listen to that advice! That will be a nice motor when gone through properly, or quickly become a good anchor if you don't.

 

[jastampke]

Re: 2002 merc 25 motor seized after being laid on side for years

ok. i got the lower unit off. everything is free on it. the motor is locked up tight. the cylinders have been soaking with atf for 3 days. what do i do now?

 

[orbanp]

Re: 2002 merc 25 motor seized after being laid on side for years

I guess you need to take your engine apart, take out the crankshaft and pistons and see what is wrong.
Hopefully you have already got the service manual for your engine by now. In case you have not, here is an on-line version of it: http://boatinfo.no/lib/mercury/manuals/20jet-20-25.html
Best course of action is to look at the power-head dis-assembly sequence in the manual and proceed according to that.

Peter

 

[jastampke]

Re: 2002 merc 25 motor seized after being laid on side for years

ok, I got the motor completly torn down. The cylinder walls look good. There are no visible defects. No grooves or gouges. So should i leave the cylinders alone and rebuit the motor or should i go ahead and have it honed out? And if so where should i send it to have it honed? I see there is a rebuild kit by mercury for my motor that comes with pistons, bearings and all gaskets that runs about 400.00. Is that what i should use and how do i know what size piston to order because i dont know if the motor has ever been bored out

 

[jbjennings]

Re: 2002 merc 25 motor seized after being laid on side for years

Take it to a machinist and have him check the cylinders for out of round, size, etc. They'll know what to check. If the cylinders are perfect and you can't feel any scratches with your fingernail, and no rust or pitting anywhere on the rod journals or crank bearings, I'd just put it back together with new rings. I'd check the pistons, but oversize pistons should have a size on the piston crown, like .020, .010, or something like that. I'd get new gaskets, particularly new upper and lower crank seals. If there's no runst anywhere and the pistons check out in spec (measure the skirts for sure), I'd reuse the pistons and bearings.
I'm no expert, however. You should wait on a pro to answer your thread. Just some ideas to think about while you wait on a better answer.
JBJbj

 

[Chinewalker]

Re: 2002 merc 25 motor seized after being laid on side for years

What did you find to be the cause of being stuck?

 

[jastampke]

Re: 2002 merc 25 motor seized after being laid on side for years

What did you find to be the cause of being stuck?

seems to me just setting up for years. the pistons were stuck pretty good, and a rod bearing was pretty stiff. I had to beat the pistons out. One piston has a smalll burn mark (discolored) on the sidewall, the other piston was brown like rust and it was the stuckest of the two. but as far as the cylinder walls i cant see or feel any thing wrong. There is somecrusty corrosion stuff on the cylinder wall where the piston was stuck but all that comes off with some elbow grease and scotchbrite.

 

[jastampke]

Re: 2002 merc 25 motor seized after being laid on side for years

from reading the mercury manual its looks like honing the cylinders can be done with just a regular honing stone. Does anyone have any experience with honing a mercosil block?

 

[oldman570]

Re: 2002 merc 25 motor seized after being laid on side for years

As long as you have it torn down, now is the time to replace everything that dose not look good. It could save you another teardown an more $$$ if just one item is not up to specks, and goes south in a short time. JMO
Oldman570

 

[Faztbullet]

Re: 2002 merc 25 motor seized after being laid on side for years

from reading the mercury manual its looks like honing the cylinders can be done with just a regular honing stone. Does anyone have any experience with honing a mercosil block?

What the manual neglects to tell you is cannot hone this with regular honing stones. Measure the bores as if motor has been the slightest bit hot the bridges on ports will warp. To repair these blocks you must bore them several times(work your way up to finished size) and hone with diamond hone to spec which is almost a polish. The pistons are a specially alloy and rings are hardened and .020 is about as large as you want to go as the bridges get to weak and flex scuffing piston. I get $135 a hole to fix these as its time consuming to deglaze cylinders,set-up to bore, and mike/watch the final honing to finish spec. To do this properly you deglaze cylinders, measure bore, set up boring bar, take a .003 truing cut and reset and take 2 more .003 passes as if you try to cut to heavy it will pull cutter into wall if it hangs. This is a bear as it is all blind cutting and then you can finish with the diamond sunnen stones as you only taking out about .0005. Also the stones(diamond) arent cheap as I gave $250 for my set.

 

[jastampke]

Re: 2002 merc 25 motor seized after being laid on side for years

ok. so i will be taking this block off to the machine shop to make sure the cylinders are good. I am going to buy new piston sets and bearings and gaskets. I have found a mercury rebuild kit with all that included for 400$. would i be better off going with aftermarket stuff and where is the best place online to get aftermarket parts for mercury?