OMC switch from copper oil tube to rubber hose.

[adam1961]

Can anyone tell me what the story is behind OMC not using an O-ring on their top bearings in the years that had the copper oil drain line, and then in 1962 adding an o-ring to the upper main and swapping a rubber hose in place of the copper tube? I am talking about RD and RK series here.

Are these changes related?

[chris-p]

Im no expert, but I don’t think they are related per se.

There were many changes that year, as you know. I think the o ring has more to do with the crank change and design.

[dan-in-tn]

I am with Chris in that they were not related to each other. The copper hose change was cost related and I may remember a fatigue excuse being given. Excuse being the key word! The upper bearing oring continues to be debated. I use a touch of gasket eliminator around my bearing shells to stop oil seepage. I have done that on all the large engine mains for years to control bearing chatter with great success. To me if you look at the block casting it doesn’t look like it should accept an oring. The groove is not well formed and there is not any fastners up high enough to offer a good crush on an oring. I did an FD and made the mistake of putting in an oring and the mag plate would not fit. Had to go back in and remove it. Just my opinion.

Dan in TN

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