gearcase drain plug leak

[pstephens46]

The LU oil DOES have to be removed for testing purposes...

Absolutely. Oil is about $10. No one has a right to complain either. "Oh I just had it changed at the dealer. I can't believe there is an issue"

I am not ragging on the OP. Just amazing that some on other sites make things so hard. Such as advice like this. "To find a leak, wait until nighttime. Get a flashlight with a purple lens. Lay down on back under lower unit with light and wait for a dribble. Could take awhile"

Or my favorite. "Go out and sniff your lower unit. Lower unit oil is stinky"

[TownsendsFJR1300]

Such an easy, quick test as shown by Scott's post. Amazing the pages of posts over at THT on leaking lowers. Just a simple test, that's all.

The LU oil DOES have to be removed for testing purposes...

[99yam40]

I believe Yamahas have the seal lips toward the outside so the inside pressure would not help to push then against the shaft

[pstephens46]

Such an easy, quick test as shown by Scott's post. Amazing the pages of posts over at THT on leaking lowers. Just a simple test, that's all.

[TownsendsFJR1300]

I would have though a couple of PSI would be adequate to simulate actual pressures encountered in operation.

10 PSI, although clearly specified in the drawing, might be a tad too high in that it might actually make the seals seal better by pushing them harder against the shafts, thereby masking the possibility that they maybe actually not be quite tight enough fitting (worn out or hard), allowing some water to pass through under normal operating pressures.

There's really nothing moving inside to make pressure (like a piston going up and down).

The PSI is just to make sure the unit is sealed tight and water will NOT intrude (or oil leak out). 10 PSI for such a short period is plenty to make sure the LU is water tight (which is the bottom line).

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[zenoahphobic]

I would have though a couple of PSI would be adequate to simulate actual pressures encountered in operation.

10 PSI, although clearly specified in the drawing, might be a tad too high in that it might actually make the seals seal better by pushing them harder against the shafts, thereby masking the possibility that they maybe actually not be quite tight enough fitting (worn out or hard), allowing some water to pass through under normal operating pressures.

[TownsendsFJR1300]

Spec's are to hold 10 PSI for 10 seconds with no leak-down/ leakage.

At least for my F150:




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[Tony Sopranzi]

Leaky drain plug

Et Al,
Sorry it took so long to get back. The tech is a friend who works at the shop. Mistake they made was to give the problem back to the oil change techs rather than a skilled technician.

The float is a black composition of some sort. I haven't installed the new one yet. Need to fill the tank with fresh gas to dilute further the ring free and Sea Foam thats in there for good measure.

Test pressure on the gear case I was told was 2psi. Just checked the plug again - bone dry, Yea!!

Now thinking about converting my manual tiller/shift/electric start/trim/tilt 2010 yamaha 25 to remote control. Thats going to be fun.

[rodbolt17]

have them look up the pressure test specification.
it is a tad bit more than 2 PSI.
your dealing with about 4 threads.
cross thread it and it is usually done.

[99yam40]

is it plastic,metal, or real cork?

[TownsendsFJR1300]

Glad it's fixed!

Was your friend associated/paid by the shop or did they leave you hanging? (just curious).


As for the float, as I re-call, it's a a solid piece, correct(like a cork)?

I doubt it's fuel additive related. Most of the generators I work on
(with a a 5 or 6 gallon tank) have a very similar float.

Same set up, floats and spins the needle clockwise.

Most don't work (float) over time. If you could find a fuel resistant
sealer (float won't soak up fuel), might be worth your while.

Or simply just keep an eye on the inside of the tank..

[Tony Sopranzi]

Leaky drain plug

Its over!!! They assigned my friend - a very seasoned and very good tech to the case and he promptly chased the threads, cleaned it up and that was the end of that. The plug screwed up nice and easy and you could feel the gaskt seat on the mating surface. between a quarter and a half turn after that "Voila" a nice even seal. He then pumped 2psi into the gear case and let it sit overnight. No loss of pressure. They filled the case and its been bone dry
over 24 hours now.

But guys look at all the fun we've had for the past few days or so. I promise not to come up with anything else for awhile. Don't want to wear out my welcome. Thanks to all who chimed in. All good stuff. But I can't resist a
parting query; Has anyone ever had a problem with the fuel floats in tempo
portable tanks absorbing fuel and sinking to the bottom? I've had two do that. Fuel was non-ethanol, enriched with Yamaha Ring Free and some Sea Foam. Sea Foam says cant be them because its nothing more than a petroleum product. Never had that problem with only Ring Free in the gas, Tempo says its either an additive causing it or a manufacturing defect. They sent me a new float which I have yet to put in. Cheers.

[TownsendsFJR1300]

Actually, a not-uncommon approach for a stripped Yamaha M8 plug is to drill and tap to 3/8-16

then stop by the Mercury dealer for a plug.

The plastic lube pump will now connect directly, no adapter needed.

Good idea but if your still drilling and tapping, the ONLY additional thing you'd be doing is screwing in the coil which is simple.

Now you have steel threads.

I believe (might be wrong) the hole for the heli-coil tap will be slightly smaller than the 3/8" tap too.

99yam, I don't think the dealer will now try to pull that. They would have earlier when they initially had it. When they gave back the boat, there was NO mention of their fix, or that it was damaged before...

In any case, a heli-coil or new larger bolt is an easy and safe fix..


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[99yam40]

I have a feeling they are going to say that they are not the ones that screwed it up and refuse to repair on their dime. I hope I am wrong

[boscoe99]

Fairdeal you need to step back away from the key board. You are making way too much sense to be on the inner web. Particularly on THT, where everyone but you, pstephens and I are crazy.