gearcase drain plug leak

[DennisG01]

There's definitely no venting of the gearcase through the plug - that could end up being a way to easily let water IN. The only way oil could leak through the plug is if the hole is drilled all the way through the length of the plug/threads. Never having seen one of these, I can't say one way or the other... but how deep is the hole compared to length of the plug?

What "air being displaced" are you talking about? When you fill gearcase? Sure - but that's why the VENT plug is removed.

Does gear oil show up inside that hole? If you clean the area well, you should easily be able to figure out where the oil is seeping out from.

[Tony Sopranzi]

leaky drain plug

You got it right. Thats what I was referring to. Hey I'm no machinist or expert in anything. Just thought they had to vent the cavity the magnet gets pressed
into so the displaced air can escape. Sounds good anyway.

[panasonic]

I would love to see it.
apparently a flat-bladed driver with a 3 mm centering stud
but I've searched the 'net without a finding a trace...

A driver tool that is in the production lathe to spin the plug blank to turn down the shank and cut the threads is what rod bolt is talking about. Other end is held by a tail stock.

The plugs in my engines are not like that..no hole in the head from manufacturing, made by a different process.

Having said that it is possible that the OP plug is leaking past the magnet and out through the center hole in head.

[fairdeal]

that hole in the plug is simply for production line assy.
makes it fit a tool.

I would love to see it.
apparently a flat-bladed driver with a 3 mm centering stud
but I've searched the 'net without a finding a trace...

[rodbolt17]

this is to funny.
3 pages on a simple leak.
why not simply pressure test the unit and fix the darn thang?????????????
it is two flat surfaces with a gasket.
aint rocket science.
that hole in the plug is simply for production line assy.
makes it fit a tool.

[TownsendsFJR1300]

On my plug there is as the link shows a whole in the middle of the head, I can not say what it is for but I too do not think it has anything to do with venting maybe how the bolt was cast to get the magnetic end on it. That is what the OP I think is talking about.

688-45341-10-00 YAMAHA PLUG, DRAIN

Agreed 100%.

[panasonic]

On my plug there is as the link shows a whole in the middle of the head, I can not say what it is for but I too do not think it has anything to do with venting maybe how the bolt was cast to get the magnetic end on it. That is what the OP I think is talking about.

688-45341-10-00 YAMAHA PLUG, DRAIN

Yes you are correct sir.

[dray0151]

On my plug there is as the link shows a whole in the middle of the head, I can not say what it is for but I too do not think it has anything to do with venting maybe how the bolt was cast to get the magnetic end on it. That is what the OP I think is talking about.

688-45341-10-00 YAMAHA PLUG, DRAIN

[TownsendsFJR1300]

No problem..

Just an FYI, there is no vent hole for the LU (or water would get in). It (the drain bolt) may very well be machined, but should not allow oil out/ water in, no venting..

Hopefully that's all it is..

[Tony Sopranzi]

leaky drain plug

Scott,
After thinking about it, I think you're diagnosis is closer to the truth.
If the magnetic tip is pressed in and became damaged somehow it would indeed open a path through the breather hole which is there so air the magnetic tip displaces when it is pressed into the stainless body has somewhere to escape. Thats why the hole is drilled through the plug.

We'll know soon enough when the new plug arrives. Thanks for taking
the time to opine.

Tony

[TownsendsFJR1300]

if it was cross threaded it will never seal.

It doesn't seal, it leaks..


.

[rodbolt17]

if it was cross threaded it will never seal.
if you need to heli coil it you must shorten the standard coil by about 4 threads.
I do a couple every year.

[TownsendsFJR1300]

I assumed that magnetic drain plug was all one piece. That magnet a
screw in fit or press in?

Very likely a press fit (snug), maybe some loctite.

Definitely was two separate parts at one point.

[TownsendsFJR1300]

Hi Scott,

Thanks for your input. Correct - I didn't look at the threads myself. The
boat is at home here in the garage and I haven't touched it for fear they'll accuse me of having boogered something. The drain plug (according to the dealer) has a new "O" ring on it. I was standing by when the tech installed
the round black gasket. I was talking with the service manager at the time and wasn't paying attention to what the tech was doing but he got my attentions when he said it feels like a burr or something up there - the plug stops turning
before it gets to its seat. But he eventually got it to seat. I wasn't aware of the new install procedure at the time having looked it up after the fact. Why is that little pilot hole on the top of the drain plug head? Is that for the lathe when the turn the threads on the plug?

I can't bold anything but will try to address your issues.

Frankly, I don't remember seeing a "pilot" hole in the middle of my drain plug but there is a magnet installed in that plug. Machining from the factory probably required it(I never knocked the magnet out so IDK).

It might be a communication problem, but even the new gasket (from what I can see, and how the LU was initially machined) is for a flat gasket. If their putting in a rubber style, thickish O-RING, NOT GOOD...

That "burr", when the bolt stops until forced, it's frigging CROSS THREADED, no doubt..

Yes it may be sitting flat now, but they screwed up the threads. Force anything hard enough, it'll seat.. Especially SS vs aluminum...

We both know it's a simple bolt screwed into a thread. Their NOT telling you
the threads are screwed up (as now their eating a self induced repair).

You NOT seeing the threads (and there's NOT alot there) leaves you in the dark.

As you've changed the LU oil before, un-screwing that drain bolt won't hurt anything. They've already damaged it.. And IF the threads aren't damaged, no foul, put it back, YOU KNOW, the threads are good.

Gentleman's bet it's tore up...

IMO, either pull the bolt (to inspect threads-it'll be VERY OBVIOUS if cross threaded), or have them do it and YOU INSPECT.

Them saying it didn't leak for a couple of days, but it does at your place?? C'mon, BS...


.

[Tony Sopranzi]

gear case drain plug leak

I assumed that magnetic drain plug was all one piece. That magnet a
screw in fit or press in?