Yanmar Transmission Fluid

[Carl sv WINDROSE]

The fluid in my KB-20 transmission on the Yanmar 4-JHE transmission has me worried.

We have owned our 1987 Hunter 40 since 1997 and have put 2300 hours on the engine and transmission. While the boat does not have an hour meter, I estimate about 3,000 hours total over its life. 100 hours ago we had the seals in the transmission replaced. 70 hours later when I checked the new transmission fluid, it had a lot of aluminum colored material mixed with the clear red fluid – it looked like a silver milkshake. I changed the fluid and now just 30 hours later there is again aluminum colored material in the red fluid.

We are in the Bahamas and have a 225 n mi trip to return to Florida. While the obvious contaminates in the fluid worry me, the transmission is still performing flawlessly.

What experience has anyone with a 4-JHE whose transmission fluid has become milky? I can get a new transmission. Should I replace the transmission with a new one before heading to Florida?

 

[Vinny]

Carl,

Are the specks metal or AL. Put a few drops on a piece of paper and see if a magnet will move them around. If AL (they won't move) then it is coming from the case or possibly the clutch pack if metal (magnetic) it is probably from a gear set or a bearing.

Does the transmission make any noise or is it overheating? Does it go into gear easily?

I'd change it again and keep an eye on it. Check it daily and see how long before it starts to show up. It could be residue from the bottom of the transmission case.

Good luck.

 

[MsEmee]

If it is milky white, you are getting water in the transmission. I would check the front/rear bearing for sure. Had this happen two years ago aboard a charter. Transmission locked up while docking. Mechanic drained the fluid and put new fluid in. I nursed the boat back to port.

 

[Vinny]

If it is milky white, you are getting water in the transmission. I would check the front/rear bearing for sure. Had this happen two years ago aboard a charter. Transmission locked up while docking. Mechanic drained the fluid and put new fluid in. I nursed the boat back to port.

McEmee,

I thought of water as well but after rereading Carl's post he says "it had a lot of aluminum colored material mixed with the clear red fluid ". It would be difficult to get water into this transmission. It is not water cooled and it sits up high in the boat. The aft cabin would have to have water 2-3" above the floor boards or more.

It sounds like it is trying to self destruct from the inside from some reason.:cry:

 

[Carl sv WINDROSE]

Vinney, MsEmee,

Thanks for the replies.

Vinny's thought about the magnet was a good one. The metallic looking stuff was not magnetic, confirming my suspision that it is the coating of the friction rings in the clutch. The coating is aluminum-bronze.

MsEmee I'm sure no water is in the fluid. It is definately metallic contamination. This model transmission is not water cooled and short of something catostropic there is no path for water to enter it.

 

[Vinny]

Carl,

I will be going to the boat tomorrow. I can check the shop manual to see if there is an adjustment for the clutch bands or not. There may be.

Anyway just make sure it is going all the way into gear and that is not the problem. So check the cable to be sure it is engaging. If it is going in and there is no adjustment point then it will need a new clutch pack at the least. If it continues to slip it will start to overheat and that leads to other problems that you do not want. At this point you could possibly just replace the clutch pack as long as the AL running around in the fluid hasn't hurt the bearings. If you overheat it severely only the case and the gear set will still be good.

The easiest thing would to be to just replace it with a rebuilt and then all you have to do is unbolt that one pull it out and slide the new one in. Actually a fairly easy job on our boat. Everything is in the open.

If you need me to look around here stateside for the transmission I would be glad to do so.

How strong is Sue feeling?