40 hp rebuild

[digtech]

My 40 hp Johnson, J40ELESR, burnt up the pistons. I have taken the powerhead down and sent the cylinder block for reboring. I am now in the process of ordering gasket kit, carb kits etc for the rebuild, will wait to see how much oversize needed before ordering new pistons. Even though this motor is 13 years old, it has not been used all that much for it's age. My question, the only damage was to the pistons and cyl walls, do I need to replace bearings? They all look like new and spin freely, no signs of wear . I need to save that $160 if possible. Thanks

 

[Mufasa]

Re: 40 hp rebuild

Hello Dave,<br /><br /> The 40 hp you have is a 1990. Does it have a VRO oiling system?? <br /><br />Don't waste your time going less than .030" over. Most of the time it will take that much just to make the cylinders round again. The main bearings and large rod/crank ends are very expensive. If they did not get metal into them and no discoloring from heat I have been reusing them for years. Make sure the shop that does the boring has had experience with the product and piston fit. If you have the VRO set up I suggest removing it and replacing it with the standard fuel pump. It is much less expensive to purchase than a replacement VRO and easy to convert. You also need to install a new water pump impeller to protect your rebuild. You can't short cut these jobs without getting burned.

 

[digtech]

Re: 40 hp rebuild

Thanks for the reply Master Tech, yes I do have the VRO which I have considered doing away with after the rebuild. I felt like the bearings would be okay to reuse but just wanted to hear it from someone else I guess