Yanmar KM4A Transmission Cooling

[jannpage]

Help please. I have a water cooled KM4a that leaks water into the transmission oil. How do I remove the internal cooler to either fix or replace it?. I can't seem to find an internal parts diagram or get Yanmar to talk to me. I have the oil out and the cover loose but there seems to be a plastic tube ---. I am being a little cautious. Thanks for any guidance.

[aries 3]

as my native language is Italian, I beg you pardon for the mistakes if any.
I'm experiencing exactly the same problem as you on my kanzaki km4a gear : I can imagine you already fixed your problem ; may I ask for your suggestion about how to do it ? Thanks so much

[jannpage]

hello. I have it out and on my workbench. When we return to the US in mid July I hope to get it either to a good machine shop or to a good local Yanmar service station or to the Major distributor. I have the cooling part disassembled as far as it can be done without some special tools so I can tell you what I have learned. Email me at jannpage@yahoo.com We are in Northern Italy now until mid July so perhaps we can swap notes easier. Your English is very good. Despite a great deal of work, my old brain is just not learning Italian not nearly good enough. Cheers Page

[Costin]

Hi, I have same gearbox, same problem. Would help me a lot to know how to get the oil cooler out of the gearbox body. I have the box on my table, removed the inner plastic tube. Looked inside doesn't seem to be cracked on the side walls, I assume it's leaking at the bottom (far end, port side), but I have no idea how to remove the body of the oil cooler without damaging it. The documentation is short and looks like it should be a simple pull with a hand.

[aries 3]

Hi Costin,
the problem on my oil cooler originated from freezing of the water : as consequence the small cooler copper pipes broken and went deformed ; disassembling of the cooler was impossible without destroing it; in my case, new spare plus labor costed approx 1000 $

[Rumrace]

I’ve seen boats wintered without antifreeze pumped through the system. As a habit power or sail I disconnect feed hoses to heat exchangers and wet exhaust and backfill with antifreeze. The plastic sleeve cracks pretty easy with a little icing expansion. This is a very common problem. The oil heat exchanger on the engine lasts a lot longer if there is fresh water flushed through it then stored with antifreeze.
Taking hoses apart to and backfill things is really amateurish but it gives me peace of mind

[Costin]

Thanks @aries, I've been checking it deeper. No way I can pull the cooler body pipe out without destroying it. It got expanded couple of millimetres on almost the full length . I'll be lucky if I can pull it out without disabling the whole gearbox or destroying it.

No idea yet.

[Rumrace]

Try spraying rubbing alcohol on the plastic

[Costin]

After trying different pulling things, I ended up cutting 2 lines down inside with a sharp chisel, which wasn’t a breakthrough, at the beginning, since it made the extraction impossible because the edges were clinging on everything inside, but I could start slicing bits of it with a tiny grinder and collect them with small pliers. It was a messy operation that took loads of hours. Trying to bend it towards the middle to pull it out was a mistake that costed me several hours. It shrink the working space. Finally I got it out and washed the grinding dust out of the gearbox with diesel. Filled the box several times with 1l diesel , shook gently, rotate the shaft in all gears so that the dust deposits on the bottom, drain it out. Fill several times more and suck from the bottom on the drain hole and on the oil cooler hole with an oil pump. I’ll put the new cooler over the weekend and test it.

[BerntW]

Same problem her with a frozen cooler leaking water into the oil.
I removed the transmission from the boat engine in our sailboat and got up in my garage on a table and trying to cut the oil cooler it in pieces.




It’s a KM4A1 on a Yanmar engine, boat is a Hallberg Rassy 37 from 2005.


One way or another I should get it out.


BÅ

[Costin]

This are the tools I used. Couldn’t have done it without the small grinder (Dremel 3000). The transmission is back on the boat seems to be working good.

[BerntW]

I have a similar grinder and will try the same process this evening (if all oil is out).
New cooler parts are ordered from Lidingö Marin and will take a few days to arrive.


BÅ
Tullinge south Stockholm