55 Johnson CD12

[iron]

I just completed a powerhead rebuild and other lower unit parts and when I inspected the bearing and seal housing below the impeller plate I noticed a small crack and replaced that as well. After i installed it I found that the driveshat was very hard to turn. I then inspected the driveshaft and noticed a small burr around where the driveshaft comes in contact with the brass bearing. I then sanded the burr down and that seemed to loosen things some. I then decided to install the powerhead and then pulled the cord a few times but it still seems way too stiff. I assume that it is tight because of the bearing being new. Since the housing is aluminum , the bearing is brass, both soft metals. Does anyone think it would harm anything if I fired it up? or that it just needs to break in?

 

[Joe Reeves]

Re: 55 Johnson CD12

1955 5.5hp Johnson, model CD12. I'd suggest that you double check your work and parts. There should be no tightness, binding at all. Running a engine that has a binding problem usually results in the overheating of metal... steel turns blue, that sort of thing.

 

[Chinewalker]

Re: 55 Johnson CD12

Hi Iron. Usually a tight turning lower unit of that style indicates a problem with the lower driveshaft/shock absorber assembly. Could be as simple as not having the right gasket (or any gasket) between the bearing plate and the main housing. Check to see if loosening up the bearing plate changes anything. If it does, you may want to try a thicker gasket.

Wouldn't hurt to inspect the lower driveshaft assy. while you're in there...

- Scott

 

[F_R]

Re: 55 Johnson CD12

The very thick spring breaks in the mentioned shock absorber, and when the ends ride up on each other the assembly grows in length, making it too long to fit in the alloted space. That breaks the bearing plate and/or causes the burrs and tightness that you mention. It's actually fairly common. The shock absorber body is two pieces which are able to rotate in the center. The spring is inside. You can see it in there if you look down through the hole that the upper drive shaft goes into. The whole absorber is replaced as a single unit.

 

[wbeaton]

Re: 55 Johnson CD12

Second to what FR said. I had the same thing in a 1955 7.5hp. However, I wasn't as fortunate as you. I haven't found a replacement bearing housing, yet. At least not at a reasonable price.

 

[iron]

Re: 55 Johnson CD12

1955 5.5hp Johnson, model CD12. I'd suggest that you double check your work and parts. There should be no tightness, binding at all. Running a engine that has a binding problem usually results in the overheating of metal... steel turns blue, that sort of thing.

I will be checking out the inside when I tear it down again. Everything seemed to be turning fine before I installed the new bearing plate. I suspect that the bearing may be a little too small for the shaft ( no play at all) Since this is a friction bearing, some play is needed for oil to lubricate the parts. I will mic the shaft and bearing to make sure. Like I said earlier, the lower turned smoothly with the old bearing plate so this is why I suspect the new housing. One thing though, is when I tighten the impeller housing that is when the tightness occurs. But since I am not the greatest with lowers I am shipping it off to my good buddy Ralph at The Outboard Wizard (Lindenhurst outboards) for a good inspection.

:/:/:/:/