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and refill with OEM quality gear lube…
Any suggestions what should be used? In ’57, the OEM said OMC type C which, if I’m not mistaken, was SAE90 gear oil. Lubricants have come a long way since then…is there anything wrong with the WestMarine 80W-90 Hi Viscosity marine gear oil that I’ve been using? Is it not “OEM quality”?
I know there’s some gear oils available that are specifically marketed as “Type C”….but they all say that they’re for electric shifting, which I don’t have. Does it matter? Should I be using this?
Don’t overthink this too much, looking for issues that might not be there…
That may be the best suggestion of all! …and I thank you for it!
One last thought: the more I read, the more I find people saying “never re-use the plug washers”. Guess what I’ve reused? 🙂
But as I look over the ‘net, I’m not seeing a real clear picture of what washer to use. The plastic ones seem to be the most common, but I’m not certain which to buy. Johnson part # 27-284 is the correct-but-obsolete OMC number. What is a modern, plastic equivalent? Is it Sierra 18-4248-9? As absurdly overpriced as these are, I’d prefer not to make a purchasing error .
.Theoretically, they should be replaced everytime, but it is rare that this actually happens. And, it is rare that they actually leak…But, it surely is possible. Like I said, the biggest issue is inadvertently having two washers in one hole, and none in the other…Or, perhaps adding an extra washer when there is already one hiding in the housing cavity…You would have seen oil dripping on a hard surface below the gearcase if the lower washer was an issue…Not so much with the upper washer though…Again, please get a good look inside those cavities using a pick to make sure a washer isn’t hiding in one/both of the cavities in addition to one that might be on the screw.
There were a few different of these washers used back in the day, didn’t mean to blanket prescribe the 311598 which might be a tad too big for some of those RD/Bigtwin/40hp gearcases. What year/hp is your engine?I think I may have had a “eureka” moment today…and it dovetails with fleetwin’s post above: A gasket is a gasket & a screw is a screw, right? Not so fast!
Unlike most of you, I’ve had…over the years…a few ’50s and ’60s engines, but right now I only have one. My “pieces & parts” drawers are not as extensive as yours…so all I seem to have are four (4) plugs, and they’re all different head diameters:
At this point I can’t tell you which 2 were in this engine and which were in my parts drawer. But what’s even more interesting is my gearcase: the two race holes are not the same size. Yes, they’re both 3/8-16, but the race where the washer & plug head seat are different.
Lower plug hole race: 0.546″
Upper plug hole race: 0.610″
I have only one (1) plug that fits my lower…the 0.534″
…but my 0.546 plug will not fit in my 0.546 port.
It is entirely possible that my “seal” was metal-on-metal and the washer wasn’t compressed at all. This could be the source of my leak
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