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Kanzaki KH18 Transmission Rear Seal Leak

john Gonzalez

john Gonzalez

Member
A set back. As I am rushing to get my boat in the water, it is clear that I have a leak coming from the seal at the output shaft of the transmission. I tried to search this site and the Web for information on this but most discussion is on the Hurth transmission paired with Perkins engine. My 3QM30 is now running nicely and dang, the leak cannot be denied. Any advice? can the seal be replaced without again my dropping my rudder which was done for the PSS dripless, I don't want to experience that again.
 

Oil Seal TC54709 you should be able to pull the transmission with only a couple of inches if you need to you could unbolt the motor mounts and slide the motor forward two inches. The numbers of the seal tc54709 in most cases indicates the dimension 54mm inside 70mm outside 9mm wide.
When I swapped my transmission I was able to unbolt it and take it out the access door no problem email me any questions you should be able to get the sale local or on line
 
Thank you very much. I have called the dealer for Yanmar to find the part and they are still looking. I can now give them the part number. Had a long talk with a mechanic friend I know and he is talking dropping the rudder which I only do if last resort as that was the hardest thing I have done so far on the refit due to access to the quadrant and rudder shaft etc, plus I 5200'd the grudeon pin (sp) on the rudder, I know I shouldn't have but did, so the thought of cutting out that sealant makes me want to call home. So thanks much for the part number and your advice to move engine forward if necessary.
 
Thank you. I have placed my order on this site. this weekend will back out the shaft as far as I can to see if that will allow the output coupler to come off. Thanks again.
 
I had the shaft disconnected from the Yanmar 3QM several times last summer and know that the shaft should move several inches aft once you unbolt the shaft coupling from the transmission flange. I don't know exactly about the PSS shaft seal but you would have to loosen that as well but then the shaft should slide several inches until the prop hits the rudder. I would hope that would be enough for the transmission to be taken out.
Steve
 
Thanks Steve, I will be working on the boat this weekend to gain the space I will need to obtain the room to take off the output coupler part. I hope I don't have to remove the transmission itself. The plan is to see if there is enough room to back out the shaft. This will require backing out the shaft from the stainless steel collar to the PSS shaft seal. Luckly, I have not installed the set screws into the collar. But the shaft log is tight on the bellow portion. It barely fit over the shaft log so it will take some work to push that back until the shaft touches the rudder. That will be all I can go. If by backing out the shaft I have enough room to take off the output coupler, I will be close to getting this done. But you have to get a tool on the nut to take that off, so there has to be room for the hand tool. But that there the room for the tool, then I will not have to take the transmission out or move he engine forward.

I found two web postings regarding replacing the transmission rear seal that are good with pictures. I will try to find them again and give the link. I made a paper copy of the articles. If there is not enough room, I will let it be the call of my friend mechanic as to moving the engine forward, which sounds the best way to go. But if I have to, I will take out the transmission. I am simply not up to dropping the rudder for reasons stated above.

I have ordered the seal, but the delivery date is in two to three weeks. So I have time to get it set up to do the seal removal operation. I will try to take pictures to post when I get to this. in the meantime, thanks all for the sage advice. The site has been invaluable. A mechanic I am not, and so these sort of projects overwhelm me somewhat and seems mountaineous. Rather do glass work and the other projects I have left before going into the water.
 
Update, the wrench to take off the spindle nut off the output shaft coupler is essentially unavailable in the US and so I tried to make one from an example off the internet, which did not work as the nut is rusted/corroded on the output shaft. It will take some umph. I have been spraying PB Blaster on it and still, cannot turn it with the homemade wrench. The Yanmar dealer tells me they located the special wrench for the removal in Japan. $245 for the wrench and then there is a tool for keeping the shaft turning while trying to take the nut off. I am thinking that I will have to bite this bullet and order the tools. A few diesel mechanics I have talked to can't seem to help. Might need to remove the transmission to remove the nut.

This is holding up my splash date. Dang.....
 
John,
On your penetrating oil, PB Blaster, try a home made mix...

50/50 mix of transmission fluid and acetone. In a spray bottle or whatever it takes to get it where you want. It has proven more effective than anything commercially available for me. I work with vintage cars, so lots of stuck stuff. We also use a little torch heat when it is feasible too. Although not together with the above mentioned! LOL

Good Luck
Mitchell
 
John, At that point I might look to cutting the nut off with a Dremel or grinder or Sawzall if it can easily be replaced. And have a few $ ready for the swear jar!
 
Thank you John and Pete. For all of us with the Yanmar and the KH 18 Transmission. Great engine but parts are dwindling for both without question. The output shaft lock nut was not available with parts dealer. They are looking with others on the computer. Yanmar USA corp office is of no use. You will be placed on hold and forgotten. Through many calls, I found a Yanmar service company an hour away that has the output shaft lock nut wrench and output shaft coupling lock wrench as part of their tool arsenal and will work on this project for me and put in the seal if they can get it off. They ask that I order a new nut and so that is what the local Yanmar parts company is looking for now. In the meantime, I will try the transmission fluid and acetone mix. Cutting the nut I will leave to the service company. At this point paying them 110 an hour and a dollar a mile from there location to mine, is fine with me as I throwing in the towel until they try to get it done. Thanks for your suggestions. I am taking pictures and will been with them to take a few snap shots so I can post them on this site of the next sailor with this issue. Replacing the seal is not problem, just getting to it is.
 
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