gearcase drain plug leak

[Tony Sopranzi]

leaky drain plug

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?

[TownsendsFJR1300]

Just crawled under the gear case to take some photos to show the dealer.
Appears the oil is seeping out of the center of the pilot hole thats drilled into
the top of the plug in the middle of the screwdriver slot. Another one of life's
unexplained mysteries.

Sounds like the magnet in that lower bolt loosened up and oil's getting past it then...

[Tony Sopranzi]

gear case drain plug leak

Just crawled under the gear case to take some photos to show the dealer.
Appears the oil is seeping out of the center of the pilot hole thats drilled into
the top of the plug in the middle of the screwdriver slot. Another one of life's
unexplained mysteries.

[pstephens46]

Dealer says this morning doesn't know why its still leaking. Says the threads are fine. Wants to put in a new drain plug but has to order one in with a magnet. I'm obligated to wait for that - see if thats the problem - maybe a fracture from over torqueing?? I don't know. For now I'll have to standby.
If that doesn't work - he's at a major decision point.

I looked up the gear case exploded diagram and also the service bulletin covering the new black plug gasket installation and torqueing procedures.
Thanks to all for those suggestions as well as the helicoil and stainless
insert approach. Machinist neighbor says if they have a larger drain plug,
he would re-tap the hole for the larger size. I hope the new drain plug solves
this mess.

Wonder if your dealer is aware of the recommendations on how to torque that new gasket/oring? Posted above in a link to a different forum.

[Tony Sopranzi]

leaky gear case

Dealer says this morning doesn't know why its still leaking. Says the threads are fine. Wants to put in a new drain plug but has to order one in with a magnet. I'm obligated to wait for that - see if thats the problem - maybe a fracture from over torqueing?? I don't know. For now I'll have to standby.
If that doesn't work - he's at a major decision point.

I looked up the gear case exploded diagram and also the service bulletin covering the new black plug gasket installation and torqueing procedures.
Thanks to all for those suggestions as well as the helicoil and stainless
insert approach. Machinist neighbor says if they have a larger drain plug,
he would re-tap the hole for the larger size. I hope the new drain plug solves
this mess.

[TownsendsFJR1300]

Scott,
I don't like the drill marks on your drill press table...I hope you were not the perpetrator of that now....lol

Heck no!!!

The Russians did it!!!




.

[panasonic]

Scott,
I don't like the drill marks on your drill press table...I hope you were not the perpetrator of that now....lol

[TownsendsFJR1300]

Townsend I think the actual part number is the same just shown as 29 an 34 but has part # 90430-08020-00 unless I am seeing wrong?

No, your correct. I don't know why they did it that way. Doesn't make sense but what's new..

The same anodes thru out (at least my engine), will show say part #29 on all of them...

[dray0151]

[QUOTE=TownsendsFJR1300;149363]I would insist, when they remove the drain bolt, to see the threads on the LU. T

Look at the parts fish for your engine:
2006 and Later F25LA Yamaha Outboard LOWER CASING DRIVE 1 Diagram and Parts TWO different part #'s for each sealing washer.. Odd, why improve/change one and not the other.. I don't believe the thread size is different, just the lower bolt is magnetic..
/QUOTE


Townsend I think the actual part number is the same just shown as 29 an 34 but has part # 90430-08020-00 unless I am seeing wrong?

[TownsendsFJR1300]

et al,
Thank you for your input. The model is: F25LA ser. 6BPk 1005486

The flat red gasket was not creating any issues. There was no leak with the red gasket installed. The leak occurred after the lube was drained/replaced. The tech may not have replaced the old red gasket with a new one.

The red gasket was replaced with a flat black gasket then the "O" ring.

The boat won't go near the water until the leak is corrected.

The leak is definitely not at the vent plug but rather at the drain plug.
also not coming through the rear prop shaft seal.

The dealer has yet to articulate what the cause is - they're just changing
out gaskets. I do know they did not have a new drain plug in stock. They may have ordered one when they put in the "O" ring.

I hadn't considered that the tech may have tried to put the vent plug in the drain hole - its possible. Its also possible the tech cross threaded the threads. When I took it back the first time, a different tech did the replacement and when he hand threaded the drain plug in he said it stopped,
feeling like there was a burr or something in there but eventually he was able to screw it down to the seat against the gasket. That may have exacerbated
the problem.

If the threads are damaged, and if they tried "chasing" them before they
put in the "O" ring and it didn't stop the leak, perhaps it may require going to
a larger drain plug from a larger gear case (if they make larger plugs) and re-tap the hole for the larger plug If there is enough room up there to take a larger plug.

What a mess. All because I was too lazy to do it myself. Will know more
tomorrow when I inform the dealer he hasn't treated the cause of the leak yet.

I would insist, when they remove the drain bolt, to see the threads on the LU. The metal SS drain bolt would survive easily.

Sounds like the original tech, cross-threaded the screw, then installed an O-RING to "get by".

If the threads are messed up, your best off (either them or machine shop), installing a heli-coil or time sert.. It'd be the same size threads when done AND, you now have STAINLESS STEEL threads, much stronger than the aluminum.

Look at the parts fish for your engine:
2006 and Later F25LA Yamaha Outboard LOWER CASING DRIVE 1 Diagram and Parts

(deleted wrong information)...


*Just as a side note, I install heli-coils in carb float bowls in generators to make sure they can be FULLY drained. But, I use RED loctite, wipe out excess and let dry over night. Those threads are NOT going anywhere.(You can say overkill but I don't have and comebacks or"do overs" with my customers.).

The aluminum below is maybe 1/3 as thick as your LU (but now has plenty of threads):

[Tony Sopranzi]

leaky gearcase drain plug

et al,
Thank you for your input. The model is: F25LA ser. 6BPk 1005486

The flat red gasket was not creating any issues. There was no leak with the red gasket installed. The leak occurred after the lube was drained/replaced. The tech may not have replaced the old red gasket with a new one.

The red gasket was replaced with a flat black gasket then the "O" ring.

The boat won't go near the water until the leak is corrected.

The leak is definitely not at the vent plug but rather at the drain plug.
also not coming through the rear prop shaft seal.

The dealer has yet to articulate what the cause is - they're just changing
out gaskets. I do know they did not have a new drain plug in stock. They may have ordered one when they put in the "O" ring.

I hadn't considered that the tech may have tried to put the vent plug in the drain hole - its possible. Its also possible the tech cross threaded the threads. When I took it back the first time, a different tech did the replacement and when he hand threaded the drain plug in he said it stopped,
feeling like there was a burr or something in there but eventually he was able to screw it down to the seat against the gasket. That may have exacerbated
the problem.

If the threads are damaged, and if they tried "chasing" them before they
put in the "O" ring and it didn't stop the leak, perhaps it may require going to
a larger drain plug from a larger gear case (if they make larger plugs) and re-tap the hole for the larger plug If there is enough room up there to take a larger plug.

What a mess. All because I was too lazy to do it myself. Will know more
tomorrow when I inform the dealer he hasn't treated the cause of the leak yet.

[dray0151]

Last time I ordered and got the gaskets I got the new black ones. Just assumed it was again new and improved, but no note of any type about different process to install. Since my new ones did not leak I must have has a bit of oil on them which I usually will do with a gasket and just screwed in snug no torque wrench to use on a screw like this.

[TownsendsFJR1300]

Found it

https://www.bandofboaters.com/forum/...unit-vent-plug

Interesting...

Sounds like the gasket probably wasn't lubed (as mentioned in
that snippet) and probably bound up, ripped, etc.

It'll have to come off and inspected and / or replaced at this point.

It also mentions ALL new drain gaskets will be this...


.

[pstephens46]

Found it

https://www.bandofboaters.com/forum/...unit-vent-plug

[TownsendsFJR1300]

There is a new gasket/oring. Don't know for how many models but assume the flat red gasket was creating issues. The screw becoming loose was the issue I noticed. The update bulletin was posted on another forum.

Apparently the new and improved ISN'T so improved...(No mention of leaks previous to this service)

Just like the new and improved mushroom poppit valve...