Motor stop = slag on piston top !

[thebulldog]

Hello boaters, i have run into a snag with slag !
my 1984 2 stroke yamaha ETLN 90 hp outboard stop runing, so i take off the cylinder head and found a metallic chunk of slag about the size of a large coin,
i removed the slag & dust and used a pc of wood and a hammer to lightly tap on the piston, well that got it moving, i put it in gear and slowly turned the propeller, well the pistons move!
anyone think that the slag was a valve ?
anyone think i am into a big dollar repair if i do it myself ?

Many Thanks in advance & happy boating.

 

[99yam40]

Re: Motor stop = slag on piston top !

Slag to me means something melted.
probable piston.
Is the slag aluminum.
you will have to take apart to see what all is bad and figure out what caused it

 

[thebulldog]

Re: Motor stop = slag on piston top !

Hello and many thanks for the reply,
i have taken a magnet the the slag and it is magnetic,
the piston top has no hole through it and turning the motor over by hand is pretty easy, although it gets kind of stuck/locked at times at which reversing the direction of rotation frees it up.

what ya think ??

 

[steddy]

Re: Motor stop = slag on piston top !

Rod/crank bearing.

 

[thebulldog]

Re: Motor stop = slag on piston top !

This is not good news ....... from a motor mechanic !

what ya all think ??


A rough estimate to rebuild your motor would be about $1200 - $1500.00 which includes parts and labour. To give you an exact estimate, I will have to take apart the engine and inspect the amount of damage

 

[steddy]

Re: Motor stop = slag on piston top !

Mine cost me $1600 in parts/labor. A lot depends on the engine itself. Some 2 strokes are real cheap to rebuild. Some aren't. My experience is that multi cylinder 2 strokes are all expensive. Singles are mostly cheap; unless you have something exotic or rare.

 

[thebulldog]

Re: Motor stop = slag on piston top !

Any ideas on what could have caused the problem ????

 

[sigma]

Re: Motor stop = slag on piston top !

Cause was probably from old age.

You could tear it down and start replacing parts or get a hold of Hydro tech and see what a new power head will cost you.

IM me for more info

 

[stylesabu]

Re: Motor stop = slag on piston top !

you need to know what melted and were it came from. what caused it to get this hot? a lean run condition can cause things to melt. how thick was the "slag" aluminum melts alot faster than steel or iron, you said it was magnetic.

 

[steddy]

Re: Motor stop = slag on piston top !

Bearing desintegration?

 

[thebulldog]

Re: Motor stop = slag on piston top !

Well i got the cylinder head off and there was a pc of compacted slag , magnetic, so when i turn the flywheel to bring the piston fully up, and then back the piston down a bit, take my finger and push down on it, it will go down about a 1/8 of an inch , this is free play/slack, so there is a problem on the bottom end, crankshaft, the slag must have come from the crankshaft, the other 2 pistons dont have this slack.
Any ideas ?????

 

[steddy]

Re: Motor stop = slag on piston top !

Well i got the cylinder head off and there was a pc of compacted slag , magnetic, so when i turn the flywheel to bring the piston fully up, and then back the piston down a bit, take my finger and push down on it, it will go down about a 1/8 of an inch , this is free play/slack, so there is a problem on the bottom end, crankshaft, the slag must have come from the crankshaft, the other 2 pistons dont have this slack.
Any ideas ?????

Start tearing down on that lower end. Exploratory surgery will be your only answer. That and a bearing. How the heavy solid slag makes its way up there and beats itself into the piston, I have not a clue. I'll bet if you dump your exhaust out, you will might some slag in there, too. I did when I took mine apart...