1988 jOHNSON 60HP, RAN LOW OIL, KNOCK, REBUILD?

[newuserguy]

Hi all, I'll try to be computer savvy. I have an opportunity to buy a 1988 Johnson 60hp, one owner, with a bad knock. He thinks his teenagers ran it on low/no oil. Now it starts but knocks. My ? is related to the rubuild area. Rod and main bearings? Rings? I have not yet obtained or broken down the motor. Advice from you pros would be great. Sorry for my last idiot post. I searched and Joe Reeves had already answered the ?. Next time I'll search first. I just did on rebuild and did not find anything specfic to a general rebuild after low oil run, but still start and run with a knock. Again, thanks, Jim.

 

[KYHunter2]

Re: 1988 jOHNSON 60HP, RAN LOW OIL, KNOCK, REBUILD?

The only way to know for sure is to tear the powerhead apart.

Its probably dropped a cylinder, the knock could be a piece of broken ring, banging against the top of piston and head.

Or the piston , minus the broken ring , banging around inside the cylinder.

I'd do a compression test first, though it will probably tell you , the same thing.

I'd be sure to quit running it , until you get it apart.

You can / will cause further damage, meaning alot more money.

If it locks up totally, and the crank breaks , con-rods, etc. etc.

Heck, don't even turn it over .

In other words , pull the heads first and take a look.

Unless your getting it real cheap, you might want to pass.

If it needs to be bored , and rebuilt , it may not be worth it .

KYHunter

 

[newuserguy]

Re: 1988 jOHNSON 60HP, RAN LOW OIL, KNOCK, REBUILD?

OK, More info. It is a one owner, relatively low hours of use, tilt/trim, extra power pack, oil tank, all controls, factory omc manual. It's approx $300 for all. Hmm, I think you have the right idea, pull the heads and visual check. How about just cranking for a compression test? Is it a real risk to try it? Thanks for the info KY, I still think you guys on this forumn site are the best. Kudos to all.

 

[Walker]

Re: 1988 jOHNSON 60HP, RAN LOW OIL, KNOCK, REBUILD?

If it indeed went bad because of low/no oil then you'd be better served to pass on the deal. Every internal moving part probably has some damage, visible or not.

 

[DHPMARINE]

Re: 1988 jOHNSON 60HP, RAN LOW OIL, KNOCK, REBUILD?

1988 is a clue to what you should do.That's too old to play with.Two stroke motors can't really knock unless they are self destructing

DHP

 

[KYHunter2]

Re: 1988 jOHNSON 60HP, RAN LOW OIL, KNOCK, REBUILD?

I'll tell you what I would do. If the tilt trim , and other items you listed are good.

As well as anything else on the motor.

And you had a mind to , sell the parts on ebay .

No doubt , at bare minimum, a 50% profit .

Heck, the tilt/ trim , and controls will get your 300 back .

You still have lower unit , cowling, starter , carbs , etc. etc.

Probably at least double your money, the more I think about it.

KYHunter

 

[newuserguy]

Re: 1988 jOHNSON 60HP, RAN LOW OIL, KNOCK, REBUILD?

KY, that was part of my thinking, though, I am an experienced mech. on automotive stuff, I'm pretty new to 2 stroke. Hey, Walker, that is a good point. I'll have to do some thinkin' on it. Again, thanks to all for the info/advice. You guys make puttin' up with this blankety-blank computer worthwhile.

 

[newuserguy]

Re: 1988 jOHNSON 60HP, RAN LOW OIL, KNOCK, REBUILD?

Hey, I forgot to thank DHP. I know that in 4 stroke a knock (assuming rod bearings) is not a "throw it out" problem. Basically, I'm assuming per your statement that if it knocks, the dollars necessary to get it back are ill spent 'cause everything else is/has excessive wear/problems. Is that a correct asumption. Thanks, Jim.

 

[KYHunter2]

Re: 1988 jOHNSON 60HP, RAN LOW OIL, KNOCK, REBUILD?

There are alot of variables involved.

The only way to know the extent of the damage is to tear it down.

As far as being worth it , its up to you.

I just recently rebuilt a 115 hp , v-4 crossflow, bought a freshly bored evinrude block .

New crankshaft, pistons bearings, used old con-rods.

I've roughly 2k in the motor.

Now I have in essence, a brand new motor.

To me it was worth every penny and the time.

These motors are pretty tough, if the crankshaft didn't crack /break.

And the block is not beyond repair/boreing.

Its more then likely rebuildable.

Whether or not its worth it , your call.

I do know its nice , to know that everything on my motor is right .

And as long as I maintain it properly.

It'll be running long after I can't.

KYHunter

 

[Silvertip]

Re: 1988 jOHNSON 60HP, RAN LOW OIL, KNOCK, REBUILD?

Price out three pistons, rings, rods, rod bearings, main bearings, a crankshaft (new, used or rebuilt), gasket set, boring and carb rebuild kits. If that's within your budget go for it. If not, better pass. Oh -- and make sure the VRO works. If not, add another couple hundred or so.