Re: 54 Johnson RD15A top seal (still) leaks

[frankr]

quote OLCAH:

Frank, I agree with the problems that you point out, yet if air is coming out the vertical drain tightness of the carbon does not matter. That would mean that when starting there would be some bubbling. (no vacuum). Do you have any take on why the redesign in 1955 or if a 1955 seal might be used? (Why redesign if the original arrangement was OK?)
Thanks.

OK, let’s clear that subject up. In 1955 they made a bad mistake. They replaced the upper AND lower bearings and carbon seals with regular lip-type seals. Why? Because they were cheaper. And they turned out to be a disaster. Many 1955 powerheads had to be replaced under warranty when water got into the lower bearing. So, in 1956 they went back to a carbon seal on the lower bearing, but left the lip seal on the upper one (cheaper). And they kept that design till 1961. And none of the above had an o-ring around the upper bearing.

1962 brought a major change. The crankshaft diameter was increased due to shaft breakage problems, and also the upper bearing was bigger to fit the new crank. And yes it got an o-ring on the upper.

Yes, you can use the 1955-up upper bearing and seal in older models. But don’t even think of putting one in the lower position.

I’ll bet that if you were real creative, you could put a lip seal above the bearing in the top instead of the carbon seal. But I haven’t felt the need to try it.