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Scored Piston Skirt

bill_w

bill_w

Advanced Contributor
Continuing on my partial teardown of an 89 115 Johnson. I had a leaking head gasket, that was letting the combustion gasses into the cooling water, that totally screwed up both thermostats, and melted the plastic reflief valves. It also looks like it caused scoring of the piston skirt, that is visible thru the exhaust ports. Can I run the motor like this, or am I looking at a total meltdown? The rings and area of the piston above the rings are good, and the cylinder above the exhaust ports is good. Only the one piston is affected.

I'd like to get at least this season out of the motor, without having to do a complete teardown and re-bore. Any thoughts on being able to run it as is?

thanks,
Bill
 
I guess this is what happens when you buy a used motor , perhaps without warranty.---------------Pay me now or pay me later.------Myself I would tear it down and do a rebuild.----------Everybody works to a different standard.
 
Your unwillingness to tear the engine down at the present time is understandable, and of course that is your judgement call. The main portion of this decision, in my opinion, would be the compression readings. If the psi readings of "all" cylinders are in the 100+ range and close to even on all cylinders, then there is a good possibility that the engine would last the season... and then some.

However, keep a close watch on the compression readings. At the first sign of a major change in those readings, or the entrance of a foreign noise (knock, tap, whatever)... this would be the turning point for you.
 
I guess I'll have to bolt the heads on and see what compression numbers I get. I'll be testing the engine cold, so what numbers should I be looking for in this situation? I knew the engine had issues, but I didn't think they were this bad. And, I got it cheap enough that if I have to go to a total rebuild, it will still have cost me a reasonable price.
 
I think the scored piston will seize the engine and cause more headaches. Once there is a transfer of aluminium, it just snowballs from there. You probably have aluminium transfer because the piston overheated, by your account. Fix it now or curse later.
 
Alright, I've got another 115 (1980) that I can use for now, until I get the block pulled apart on the newer one. It runs, but I've been told that it's 'tired'
 
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