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Kanzaki Transmission to Yanmar

Had the transmission pulled from the engine to replace input and output shaft seals during the refit. Been in the water a few months now. An observation now that I am in the water. When in gear, forward or reverse, I hear the transmission working quite loudly and more noticeable than in my Hunter sailboat with Yanmar and same make transmission. This is a larger engine and clearly different size transmission but did not notice a noisy transmission. Mostly when the engine at low RPMs. Is this unique to this engine and transmission. Is it normal?. Oil level appears to be good. I was expecting the 3QM30 to be noisy but wasn't so much expecting it from the transmission. Not a knocking or anything abnormal sounding just noticeably louder than expected. Thoughts?
Hate to bring this up again, but with the noticeable whine I have in the transmission when in gear, I had a well experienced mechanic take a look and listen to my gear. He only works on diesel engine is a the mechanical engineer to a large vessel in the harbor and is well respected. I called him because of the whine and thinking I had a bearing going out which would have spelled disaster considering the lack of available parts. However, he took time to see and hear my engine run in the slip with high RPMs both in forward and reverse and did not think the whine noise was a bearing in the gear and thought that the gear us working normally and probably the PYI dripless or shaft log may be causing the noise but not the gear. He also thought the damper disk (plate) may be making the sound but was not recommending doing anything except to get the 30w engine oil out of the gear case and put in Dextron ATF fluid after flushing with seafoam solution and then refill with the proper amount of ATF Dextron 3 and add a cup of Marvel Mystery Oil due to the age.



Stephen Ruell
Just thinking and don't know too much, can only relate it to what happened to me. It sounds like you did a bunch of work on the engine and shaft. Did that include alignment of the engine and checking the engine mounts? Did you have leaking seals on the transmission? Was that why you had it pulled? Could it have been leaking due to misalignment and now they are tight and the shaft is not aligned to their new centerline?
I have posted previously that my 3QM30 actually sheared three of the four mounts off just under the engine feet where you couldn't see it. Then it proceeded to wear out the coupling where the shaft fit into the back of the transmission, so that it couldn't be retained any longer. Many mechanics worked on the engine but no one spotted that, I guess the weight of 500 lbs or so just kept it in place while the mechanic was there.
Stephen, yes the seal was leaking and likely due to misalignment. I have new mounts ready to put on and this whine issue I thought I would address before I do so in the event it was coming from the transmission. So, I think you are hitting on something that makes sense. THe mounts are still in tack but are original so I ordered new just to allow less vibration when running. I think all this in interrelated so I will change the mounts and have the engine realign and hope will get the gear to work less without perhaps a binding from the misalignment. Any thoughts on the advice from the mechanic to run ATC after a flush with seafoam?


Stephen Ruell
If you read about alignment problems it is something that changes with time and won't stay correct over time, especially in a fiberglass boat. And the method to do it correctly seems to be a bit of a controversy.

I have no opinion on flushing the transmission, never did it. I've had three Yanmar boat diesels in two different boats, operating them since 1995, and never saw transmission seal leaks and no one ever suggested flushing it. I would suspect that while the fluid might help, you probably should check to see if you have something else going on. I never did anything but check the level on the dipstick. Not sure why you have engine oil in there, shouldn't it be transmission fluid per the book?

I would suggest you install the new motor mounts and do an alignment. The Yanmar owners manuals say that engine mounts need to be changed out after so many years as preventive maintenance- I forget the actual times but it was like 5 or ten years, anyway not very long but probably depends on the usage. The forty years that all these Morgans have is definitely outside the window.

We changed out our Yanmar 3QM for a Beta 38 because we couldn't figure out the shaft problem and didn't want to spend another summer disabled. Comparing the two I would say that the Yanmar 3QM is not a well balanced engine and had so much vibration that it probably was what did in the engine mounts, but maybe it was the other way around. Anyway if we had investigated better and learned of the broken mounts before they actually were pulling the engine, we might still be running it.

I hope you can figure out your issue or if you even have a problem.
Good luck,


Stephen Ruell
I just looked it up in the owners manual and the Kanzaki KH18 transmission should have ATF fluid while the other YP transmission uses engine oil.
Stephen thank you very much for all your input. The motor mounts will get changed as they look sunken and the rubber hard so that is needed and I am hoping that will help with the vibration and from there, an alignment should be done to keep the transmission from having an uneven load on the internal parts particularly the bearings. I've gone back and forth about the lubricant and it is controversial too however the mechanic I referred to was very confident that ATF is what needs to be in there as oil keeps the transmission hotter than ATF and has additives that are not meant to be in a transmission.. Thanks again !


Richard Kilroy
I have always used automatic transmission fluid in Vixen’s transmission. I am the original owner. Over the 43 years I have only had one engine mount failure. The engine is the original Yanmar 3QM30. The motor mount that failed was the front one starboard side as you look at the engine. Caused engine misalignment and cunless bearing failure. Cause was the mechanical fuel pump located above this engine mount was dripping very small amounts over a goodly number of years.
The original Yanmar motor manual states different things. In one location it tells you to use transmission fluid and in another it tells you to use 30 weight engine oil.


James M. Cleary

As part of my fuel filter changing routine. I always cover the stbd forward motor mount with a one gallon zip-lock bag. As neat as I try to be there is always diesel fuel that drips from the secondary filter. That mount has been changed twice before I picked up this trick. Now the zip-lock lives in my oil change kit ready to protect the mount.

Thank you Warren, Dick and Jim. Sage advise from those who have experienced perplexing question of mine for several years. I know a little about the systems of our sailboats but when it comes to the engine, I am behind the curve for sure.