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danalex

Contributing Member
My 1986 60 3 cyl merc burned the electrode off the top spark plug. I am trying to look at the manual to see what I might be able to do. It did not burn a hole in the piston but I know there is aluminum in the cylinder. Anyway, any idea why access to the manual is suspended? I have used it a lot and it is a tremendous help.
 
I might be able to get to the side of it. I am wondering and researching, is it worth rebuilding. The solenoid seems to have went out during that same trip night before last. A rebuild kit is about $600. When I took out the top plug, the bottom of the plug was almost sealed with forged aluminum. Put the plug in and tightened and it broke that out of the way, so it is in the cylinder now. I still have 80 lbs compression across all three cylinders which is amazing. I have no idea what to do next. Is it worth getting a look inside?
 
On the upside, the seals in the foot are great, oil is perfect, no leaks and shifting wonderfully. Water pump is great. Man. I have put a lot of time and money in this thing.
 
I pulled the side cover. The bottom two pistons and cylinders look pretty good, minor carbon on top, rings all free and tight in cylinder. Top piston looks good, the side I can see; cylinder is scored, but nothing that would hold a fingernail, more cosmetic. (Best I can see). Top ring moves, bottom two either froze or move very little. careful Press with tip of screwdriver on the bottom two rings does not move noticeably. I only broke off one bolt getting that cover off. Got some medium corrosion going on with the bolts.
 
Typical of those engines is that the fry their top cylinders.

First of all, I would do a compression test and see what's left up there.

Jeff
 
That plug in cylinder was aluminum throw off from piston deflector...typical sign of pre-ignition. Can be caused by wrong plug type, plug lose, ignition problem. Will need to be torn down and repaired.
 
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the first thing i did when I got back with it, next morning, was test compression. 80 pounds all three cylinders. No deviation. Low compression, yep. But with the same across the board, which is strange, I might put it back together, put new plugs in and run it till it won't. I am deep enough that I could proceed pretty easy, but I don't have a manual, and there are a couple other things I am missing for a rebuild. I have no shop here, working on the motor on the back of the boat; have to build a table to hold the head, putting the pistons back in is gonna suck without clamps, and I want to go fishing. Kit for rebuild is 600 dollars. I can do it cheaper, I don't need the pistons, just rings and gaskets. Unless I find piston damage. I need to find someone who can bore or sleeve it, I have no idea where or who. Argh. And I have a bolt with the head broken off I've been working on for 2 days now. About a half inch of the threads showing. Holds the exhaust cover in place. Guess I will try to drill it out, wax and heat and pb blaster arent moving it. And I got cheap vice grips, cannot find my good ones, will go get a new pair that actually works and try them before drilling.
 
Before you do anything, try another compression tester. From my experience with these motors (and lots of it) those even readings--if they are low because of that tester--MIGHT mean your motor is okay. Find out FIRST. Good readings with a good tester should be above 140 psi.


Jeff
 
Wow. Had a wall of text and got an error on submission. I just got back from six hours on the water. Motor does excellent at WOT. Doesn't like to idle unless I run fast for 5 minutes or so, then I can putt around as much as I want for at least 20 minutes. If I crank it and try to drive at idle speed it dies unless I snatch it wide open; sometimes dies then also, have to start over with cranking routine at that point. Crank routine: Choke while turning over till it fires(5 -6 revs). Take choke off, start it. Maybe 3 - 5 revs. Then snatch it wide open or it will die. After a little WOT, will idle fine. When first launching, ran fine at idle all the way through no-wake zone, a good 12 minutes. Just after running a bit it gets cranky. Ideas?
 
I'm going to start another thread. I am not going to get any info on this thread subject and it is misleading. Thanks for the help, hope I see you guys on the new thread.
 
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