90HP Dead Cylinder Question

[again]

The boat was a recent purchase and I think this was the 4th time I took it out. It ran fine for 15 minutes, then would not idle. Got towed back to shore and put it in the shop. A compression check showed cylinders 1 and 2 at 135, cylinder 3 had 40. Shop quoted $4400 for a new power head & labor (not gonna happen).

I borrowed a gauge and verified 40 psi on #3. I took the head off and found that all 3 cylinders had the cross-hatch scoring on the cylinder walls and cylinder 3 had a couple of gouges in it (I'll attach a link to pics once I get them uploaded to Photobucket). Guess somebody's been in the motor.

The gouges are not consistent up the entire cylinder wall. Could it be a broken reed valve? I don't want to put alot of time and money into a repair as money's tight enough. I'm just trying to decide if I should cut my losses and sell it as is or pull the carbs to see if it is the reed valve.

Opinions please.
Thanks.

 

[Barnacle_Bill]

Re: 90HP Dead Cylinder Question

Reeds are not causing that low compression. Probably broken rings. That motor needs to be rebuilt.

 

[again]

Re: 90HP Dead Cylinder Question

Here are the pics - doesn't look good.

 

[Frank Acampora]

Re: 90HP Dead Cylinder Question

4400? OUCH! You can do it (all three cylinders) yourself for less than 1000. It does look like the engine swallowed something, or a ring may have broken. At any rate, a .030 overbore on the affected cylinder would probably clean up everything.

AND, You need only to do the affected cylinder. Figure about 3-400 if you do the labor yourself.

Get a manual. Primarily hand tools are needed with a flywheel puller and an inch pound torque wrence as the only specialty tools.

Depending upon the engine year, you may not need a press to push out the wrist pins. Before 94 they were press fit; after, I don't know exactly when, they were held with circlips.

Strange: in the photo, the piston crown looks too new for the damage that scored the cylinder. Too clean too. I would have expected to see dents in the top of it and more carbon. Perhaps the previous owner replaced the piston and was not satisfied with the result so sold the engine?

 

[GrindKore]

Re: 90HP Dead Cylinder Question

It don't look too bad, I have had similar problem last year and after about 1 week in the garage (mostly waiting for parts to arrive) and just over $400 I was able to repair it. Check out my thread here http://forums.iboats.com/showthread.php?t=266436

 

[again]

Re: 90HP Dead Cylinder Question

Can I do the overbore with the motor (or power head) in place? Excuse my ignorance - never done anything like this. Looks like pulling the piston(s) is pretty simple - pull the carbs and reeds and unbolt them from that side. Is that correct?

Thanks for the help.

 

[GrindKore]

Re: 90HP Dead Cylinder Question

Can I do the overbore with the motor (or power head) in place? Excuse my ignorance - never done anything like this. Looks like pulling the piston(s) is pretty simple - pull the carbs and reeds and unbolt them from that side. Is that correct?

Thanks for the help.

No, to bore cylinders you will need to remove the head and disassemble the block completely. However, in all likelihood you may get away with just replacing rings or a piston. Truth is these are old motors, unless you have skill and dedication to make it perfect again I would not bother. My motor after last years piston replacement is chugging along very well, I have compression in mid 120s on all 3.

 

[mmccoy555]

Re: 90HP Dead Cylinder Question

Judging from the holes in the cylinder wall and the nicks on the ports the bottom of the piston is busted. Obviously you will see it when you take it apart but I'm willing to bet you need atleast a new piston, bearing, rings and a honing might do the trick on the cylinder wall. The two holes don't look good though.

 

[again]

Re: 90HP Dead Cylinder Question

I fixed the problem. I SOLD THE BOAT!!!!

Thanks for the help. This forum has been great.

 

[GrindKore]

Re: 90HP Dead Cylinder Question

I fixed the problem. I SOLD THE BOAT!!!!

Thanks for the help. This forum has been great.

That works too. I'm just curious, were you able to break even or perhaps profit on this transaction? Did you disclose the problems you have discovered to the buyer?

 

[again]

Re: 90HP Dead Cylinder Question

Of course I told the new buyer the problem (unlike the person who sold it to me). I showed him pictures of the cylinder and advertised it as needing a new motor.

I bought the boat in January. I put new tires, wheels, tow chain, lights, registration, spare tire carrier w/lock, and straps on the trailer.

I put new 2 year lake registration, a new 160 watt Jensen CD stereo and speakers, Hummingbird fish finder, recovered one seat, new ski rope, skis, new life vests, new horn, dock bumpers, starter, lower end grease, spark plugs, and hydofoil, and a 5 yr boat cover on the boat.

I sold it for $1500. Lost $2000.