1984 Johnson GT 150 rebuild???

[bighead]

Thanks for all the responses to my last post. I'm thinking about a tear down and rebuild on this engine after Christmas as the previous owner reported that the outboard has many hours not to mention the knock or slap that it still has. I won't be fishing for a couple of months so I should have time to get it all done. I've worked on many automotive and motorcycle engines including rebuilds but never a outboard. I've ordered an OMC manual for this engine but have some questions. Are there any special tools required to do this besides normal hand tools? Should the crankshaft be turned to an undersize and new bearings installed as is common on automotive engines? I have a dial bore gauge and will measure the bore taper. Is an auto machine shop able to bore the block should it need it? Any other advise you might have to offer? Thanks again. bighead

 

[Walker]

Re: 1984 Johnson GT 150 rebuild???

Should the crankshaft be turned to an undersize and new bearings installed as is common on automotive engines?

No, as far as I know there are no oversized bearings available. If your crank is damaged there are a couple of places that can rebuilt it to specs.<br />You will need a torque wrench calibrated in inch/pounds.

 

[R.Johnson]

Re: 1984 Johnson GT 150 rebuild???

Many automotive shop's can have a problem with the interrupped cut that a ported outboard engine present's, also the port's have to be lightly chamfered after boring, and honeing. After boring, on an OMC engine, the bottom of the cylinder should be slightly under-cut, plus the deck, or top of the cylinder liner, and block should be brought into agreement. This take's a very slight cut, as to not change compression figure's. After that, it is a rather straight forward rebuild. Check all bearing surface's for wear, or any sign's of pitting. Replace the bottom crank ball bearing, and of course, all gasket's, and seal's.

 

[TimMattson]

Re: 1984 Johnson GT 150 rebuild???

I work for a dealer who used to be OMC and still services them.We have a GT150 out back that the boss says is a good motor to rebuild.The Crank will be the key....Rebuild the carbs for sure and update the cooling system(thermostat may have a new version available) and a fresh waterpump is a must.Youll need a product called Gel-seal to assemble the crankcase halves,applied very carefully.<br /> Tim Mattson <br /> Sorensen Marine