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-   -   Dropped a straw in my gearbox!!!! (https://www.cruisersforum.com/forums/f54/dropped-a-straw-in-my-gearbox-233960.html)

a64pilot 10-05-2020 15:58

Re: Dropped a straw in my gearbox!!!!
 
I’m thinking it’s a drain that’s in the water jacket, not the oil side, so it’s exposed to salt water if I’m right.

Compass790 10-05-2020 16:02

Re: Dropped a straw in my gearbox!!!!
 
[QUOTE=Swift Drift;3136680]
Now I need to make a decision on what to plug the hole with. Iím tempted to use a stainless bolt with some tef-gel or lock-tite on it. But Iím concerned about the whole dissimilar metal scenario.
Am I making a bad decision by going with a stainless bolt? I think the cooler is bronze? Pretty sure the old corroded petcock was brass.

I believe ss is fine with bronze. Many bronze HX have ss bolts. Think they are close in galvanic table.

Swift Drift 10-05-2020 16:12

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by a64pilot (Post 3136696)
Iím thinking itís a drain thatís in the water jacket, not the oil side, so itís exposed to salt water if Iím right.



That is correct. As for machine threads vs NPT, I am not sure. I chased it with an ďM8 x 1.25Ē tap and it threaded nicely.

It sounds like stainless with Tef-gel would work fine provided I use the correct threads.

The mounting bolts appear just normal steel bolts by the way. However they do not come into contact with raw sea water.

Wotname 10-05-2020 16:37

Re: Dropped a straw in my gearbox!!!!
 
FWIW, all the Yanmar petcocks that I have ever seen have had BSP threads.

Technically they are JIS threads but JIS is interchangeable with BSP for all intents and purposes.

Wotname 10-05-2020 16:41

Re: Dropped a straw in my gearbox!!!!
 
Also FWIW, many (but not all) Yanmar heat exchangers use cupronickel. It there is no anode in the system then I would bet it is cupronickel.

Smokeys Kitchen 10-05-2020 18:53

Re: Dropped a straw in my gearbox!!!!
 
Simple reply for this thread:

Glad you got your problem (at least the original one) solved and thank you very much for posting the result. Too often we are left wondering "what happened"?

a64pilot 10-05-2020 19:45

Re: Dropped a straw in my gearbox!!!!
 
I would likely use an M8 bolt with Teflon tape and not make it real tight, cause I don’t think that’s the right thread, but so long as you don’t make it so tight it deforms the threads, no harm. This thing is under about zero pressure, there is some, not much so I don’t think you need any super tight seal. Then get somewhere where you can get the right part and see how well it fits, pipe threads of course are a little bit of an interference fit anyway.
I’d use Teflon tape cause it may seal a leak better than Tef-Gel and ought to be OK.

I think this transmission isn’t really a Yanmar? I know it says Yanmar on it, but I think it’s a Hurth? I say that as maybe the thread is different than what Yanmar uses in the engine that they build.

Swift Drift 10-05-2020 19:59

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by Wotname (Post 3136721)
FWIW, all the Yanmar petcocks that I have ever seen have had BSP threads.

Technically they are JIS threads but JIS is interchangeable with BSP for all intents and purposes.



Thanks for the insight. Iíll keep this in mind when trying to source a plug tomorrow.

Swift Drift 10-05-2020 20:03

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by a64pilot (Post 3136815)
I would likely use an M8 bolt with Teflon tape and not make it real tight, cause I donít think thatís the right thread, but so long as you donít make it so tight it deforms the threads, no harm. This thing is under about zero pressure, there is some, not much so I donít think you need any super tight seal. Then get somewhere where you can get the right part and see how well it fits, pipe threads of course are a little bit of an interference fit anyway.
Iíd use Teflon tape cause it may seal a leak better than Tef-Gel and ought to be OK.

I think this transmission isnít really a Yanmar? I know it says Yanmar on it, but I think itís a Hurth? I say that as maybe the thread is different than what Yanmar uses in the engine that they build.



This could be my best option given the circumstances. I was able to easily thread what I think is an M8 from my random onboard bolt collection. It did however have a slight wobble to it, indicating it isnít a perfect match. The wobble was small enough that Teflon tape could easily snug up.

Swift Drift 10-05-2020 20:28

Re: Dropped a straw in my gearbox!!!!
 
2 Attachment(s)
An interesting point of clarification that doesnít directly help my situation at hand but wanted to pass on: Iím thinking I have a KBW 21 rather than a KBW 20.

It seemed fishy that mine has the oil cooler system and no other kbw 20ís seem to. I have however seen pictures of kbw 21ís and they have an oil cooler.
I originally thought I had a kbw 20 because of the lower stamp in the below pic that says ďKBW 20Ē. However, the upper labeling clearly identifies it as a ďKBW 21.Ē Confusing but my hunch is that the presence of the oil cooler confirms KBW 21.

Attachment 214800
Attachment 214801

wsmurdoch 11-05-2020 04:36

Re: Dropped a straw in my gearbox!!!!
 
1 Attachment(s)
Quote:

Originally Posted by a64pilot (Post 3136815)
I think this transmission isn’t really a Yanmar? I know it says Yanmar on it, but I think it’s a Hurth? I say that as maybe the thread is different than what Yanmar uses in the engine that they build.

Yanmar KBW10, Hurth HBW10.... from the shop manual.

Bill

Cool Hand Luke 11-05-2020 09:56

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by kmacdonald (Post 3135850)
Sell the boat and let the new owner worry about it.

I will never buy a used boat ever again :facepalm:

Swift Drift 11-05-2020 15:38

Re: Dropped a straw in my gearbox!!!!
 
1 Attachment(s)
Ended up tapping the hole out to 1/8 NPT and using a brass plug. Will try and source a bronze plug later.
Everything is back together and performed well with testing at anchor.

Remember folks, never stick anything in a gearbox fill hole thatís shorter than the gearbox. Thanks for everyoneís input.

Attachment 214871

Swift Drift 11-05-2020 15:40

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by kmacdonald (Post 3135850)
Sell the boat and let the new owner worry about it.



There is a special place in hell reserved for people that do this.

Wotname 11-05-2020 15:51

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by Swift Drift (Post 3137471)
Ended up tapping the hole out to 1/8 NPT and using a brass plug. Will try and source a bronze plug later.
Everything is back together and performed well with testing at anchor.

Remember folks, never stick anything in a gearbox fill hole thatís shorter than the gearbox. Thanks for everyoneís input.

Attachment 214871

For future reference, you can fit a male NPT into a female BSP (in the these small sizes). It will be ever so slightly loose but works OK when a suitable thread sealant is used. However the reverse is not true i.e. a male BSP does not work in a female NPT.

If the large plug at the bottom of the picture is a anode (it looks like one to me), then the brass plug will be good for a long time; of course, a bronze one will be better!

kmacdonald 11-05-2020 16:01

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by Swift Drift (Post 3136680)
Well, during reassembly I snapped off the petcock drain at the bottom of the oil cooler. I was able to extract the remaining section and chase the threads in the cooler with a tap so they are good and clean.
Now I need to make a decision on what to plug the hole with. Iím tempted to use a stainless bolt with some tef-gel or lock-tite on it. But Iím concerned about the whole dissimilar metal scenario.
Am I making a bad decision by going with a stainless bolt? I think the cooler is bronze? Pretty sure the old corroded petcock was brass.

Attachment 214771

Attachment 214772

Ohhhhhhhhh boy. Here we go again!!!!!!!!

kmacdonald 11-05-2020 16:13

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by kmacdonald (Post 3135850)
Sell the boat and let the new owner worry about it.

Quote:

Originally Posted by Cool Hand Luke (Post 3137202)
I will never buy a used boat ever again :facepalm:

Quote:

Originally Posted by Swift Drift (Post 3137472)
There is a special place in hell reserved for people that do this.

For sale. Owned by a surveyor, rebuilt diesel. That means it had an oil change by a grease monkey.:biggrin:

Boatwright 12-05-2020 06:14

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by a64pilot (Post 3136689)
Usually they arenít machine threads, often they are NPT.
If itís machine threads then Iíd use a bolt with tef-gel with the intent of changing it later with something bronze, if itís NPT, then I believe Iíd be tempted to use a PVC plug if you can find one, there is no real pressure there, and brass as a last resort, with the intent of later putting on whatís supposed to be there, surprised if it was brass.
I donít have a cooler, but there are I believe similar drain pet docks on the heat exchanger and a couple of other places on the engine, one is I believe plastic.

Yanmar May also have used a wierd British thread, but I donít believe this is really a Yanmar transmission, maybe not.
My 4-JHE uses this weird British thread on its oil galley plugs, I ran into that when installing an oil pressure gauge.

I think the KBW-20 is a Hurth transmission built under license?

Weird British thread is correct. Japanese and British pipe threads are the same. Since you are down on the Antilles, you may be able to find a Brit pipe-plug or pet-cock to fit. I wouldn't try to jam a mismatched bolt in and make things worse. :thumb:

Swift Drift 13-05-2020 06:33

Re: Dropped a straw in my gearbox!!!!
 
Does anyone know where I can source a service manual for the KBW 21?
All of this messing about has inspired me to have one on board.

jimbunyard 13-05-2020 06:55

Re: Dropped a straw in my gearbox!!!!
 
https://www.manualslib.com/manual/13...age=159#manual

The 20 and 21 use the same manual. The link above is for the engine, the KBW20 and 21, and, I believe, but didn't look, the saildrive transmission.


By the way, not sure if, in the discussion about plug materials, anyone mentioned it, but it's better to have a less noble metal as a plug material than a more noble one, so that the plug 'sacrifices' rather than some other metal in the transmission. Probably best to have the materials within .15 V on the galvanic index, as described in this article, so neither 'sacrifices'.

https://www.corrosionpedia.com/an-in...rrosion/2/1403

Swift Drift 15-05-2020 07:26

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by jimbunyard (Post 3138680)
https://www.manualslib.com/manual/13...age=159#manual

The 20 and 21 use the same manual. The link above is for the engine, the KBW20 and 21, and, I believe, but didn't look, the saildrive transmission.


By the way, not sure if, in the discussion about plug materials, anyone mentioned it, but it's better to have a less noble metal as a plug material than a more noble one, so that the plug 'sacrifices' rather than some other metal in the transmission. Probably best to have the materials within .15 V on the galvanic index, as described in this article, so neither 'sacrifices'.

https://www.corrosionpedia.com/an-in...rrosion/2/1403



Thank you sir!

Thinking to to the future, does anyone know of a good source for rebuild parts? Clutch packs, etc.

a64pilot 15-05-2020 08:00

Re: Dropped a straw in my gearbox!!!!
 
Quote:

Originally Posted by Wotname (Post 3137477)
For future reference, you can fit a male NPT into a female BSP (in the these small sizes). It will be ever so slightly loose but works OK when a suitable thread sealant is used. However the reverse is not true i.e. a male BSP does not work in a female NPT.

If the large plug at the bottom of the picture is a anode (it looks like one to me), then the brass plug will be good for a long time; of course, a bronze one will be better!

It will fit, sort of. I believe it will be ever so tight though, I know that you can tap a 1/8” BSP to a 1/8” NPT and if the BSP was larger, you couldn’t.
I gave up finding an adapter and based on advice from Mack Boring, tapped my engine to accept an NPT oil sending unit, Just put grease on the tap to trap any metal particles.

I would also say that if the plate is iron, then if you can’t find a bronze plug, and iron one ought to work. Iron plugs are common in house plumbing.
But the brass one will work, but I’d replace it eventually


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