Main seals on CD-15

[TTravis]

Can anyone tell me about the main crankcase seals on a 1958 Johnson CD-15 5.5 HP? I suspect I have a air leek and being such an old motor, need to replace the upper and lower seals. Anyone know the part number and a good source? I don't see them listed in my Siara catelog.<br /><br />Tom Travis

 

[Paul Moir]

Re: Main seals on CD-15

I thought the early 5.5hp powerhead simply used an oil slinger rather than a seal for the top seal. It should be a little plastic thing that lifts off after the cam on the crank. Usually when I find an outboard with an upper seal problem, the coils and points are covered in oil from it blowing out.<br />If I'm wrong, a local bearing house should be able to fix you up with a replacement if you bring the old one in. Look in the yellow pages under 'bearings'. Normally they supply industry, but they often run a little retail counter too. <br />The lower seal is held in place by the driveshaft like later 5 and 6hp engines. This is made up of a cork seal, an o-ring, some springs and such. I think it's still available from the dealer.<br /><br />Hope this helps!

 

[TTravis]

Re: Main seals on CD-15

Thanks Paul, I think I will check out a manual again from my local library and look at the exploded diagram. I've got that 5.5 together and it runs ok in neutral but when I try to put it in gear to go, I don't have any power at all. It also seems to get worse as the motor warms up. You can see what all I did to it at http://www.outboard-boat-motor-repair.com where I just added a lot more context.<br /><br />Tom Travis

 

[Paul Moir]

Re: Main seals on CD-15

That doesn't sound like an air leak to me. My experience with blown crank seals is that the engine will never idle properly no matter how you adjust the mixture, but as you pick up speed the leaky cylinder starts firing so it runs with power. Detectably imbalanced but easily 80% or more of the power.<br /><br />Call me crazy, but I have seen brand new spark plugs cause a problem like that. Have you tried a spare set? Are the spark plugs telling you anything?<br /><br />EDIT: Another thought - have you checked compression since it's fired? Head bolt torque is 60-80 inch/lbs, and if you didn't retorque after the first warmup you're going to need to.

 

[TTravis]

Re: Main seals on CD-15

I'll throw a different set of plugs in there from my Lightwin and see if that makes a difference. The plugs seem to be fowling but I've tried a lot of different adjustments and probably caused them to get that way.