Aluminum on cylinder wall?

[witenite0560]

Here's a motor question: I bought a 1960 75HP Johnson to rebuild or for parts, whichever works out. I knew going in it had at least some compression on 3 cylinders and none on the 4th. I pulled the head off the right bank after determining that it was the top cylinder on that side that had no compression. I found the cylinder has a flashing of aluminum, presumably piston skirt material, on the upper and lower areas. (Roughly from the 11 - 2 and 4 -7 positions, relative to a clock face.) My question is, is this normally caused by lack of lubrication, overheating or what? I set the motor aside, figure it's going to be at least a powerhead rebuild. I used a wirewheel on a dremel to carefully remove the aluminum as far as accessible and the bore doesn't look damaged. But,???

 

[Bubbles Up]

Re: Aluminum on cylinder wall?

Use muratic acid to remove the aluminum ,it wont hurt the chrome or the the nikasil on the bores.

 

[DJ]

Re: Aluminum on cylinder wall?

The transfer of AL to cylinder walls is almost always a lack of lubrication. In your case that means a carburetor problem.

 

[R.Johnson]

Re: Aluminum on cylinder wall?

That is a 1960 engine. The cylinder sleeve's are cast iron, not chrome, or nikosil. Measure the bore's. This will let you know what action to take.

 

[witenite0560]

Re: Aluminum on cylinder wall?

DJ, from running too lean, I presume?