Johnson V4 only rep. og one cylinder ??

[Holten]

I have a Johnson v4 140 HP from 1993
One cylinder has lost compression and need a new oversize piston.

My dealer says it is ok to only rep. this one bad cylinder.

Is it ok ???

 

[fireman57]

Re: Johnson V4 only rep. og one cylinder ??

It probably is but the cost is tearing it down and putting it back together. Why not replace that bank with new and be done with it. There are others that do this for a living and not on the side like I do that can give you a better answer. The goal is to have fairly even compression on all cylinders and I think that if you just replace the one with an oversize it will have a lot better compression than the worn ones next to it. Have the others honed and at least re-ringed.

 

[jdupree]

Re: Johnson V4 only rep. og one cylinder ??

Holten,

I had the same problem with my 1988 90 hp Johnson about six months ago. Was faced with the same situation. I agree with fireman57 that the motor will have to be tore down. I went ahead and had my block bored and put 4 brand new pistons, rings, and gaskets in mine.

If you plan on keeping the boat, I would spend just a little extra money and go with new pistons and have it bored. In the long run you will be glad you did.

 

[F_R]

Re: Johnson V4 only rep. og one cylinder ??

Back in the 1960-70's we did a LOT of rebore jobs, replacing only one or two pistons and hone and re-ringing the others. Could not tell the difference between doing that and doing them all. But you are talking about a much later model that I am not familiar with. Reboring where it is not necessary removes metal and often the possibility of ever doing it again, should the need arise.