supermalc
New member
When I got my boat in December last year, I knew nothing about the old Yanmars (didn't even know they existed) however I'll pass on what I have learnt, as it may be a help to others.
The name plate on the clutch housing was missing, making identifying it a real pain.
This is what I have been told, by experienced mechanics, and others have backed this up. It may not be 'gospel' but I think the facts are correct.
The engine was designed as a flat twin in the middle of the 1930s by Coventry Climax.
Yanmar made the engine from half of it making the YSE from 1974 to 77, YSB from 77 to 78 and YSM from 78 to 80.
The manual I downloaded says the YSE is 3 to 1 reduction and the others 2 to 1, but YSEs can be 3 or 2 to 1, so I expect this may apply to them all. Mine is a 2 to 1 reduction, and the engine runs at 3000rpm, so the shaft 1500.
The YSE has a cast iron gearbox, and the front pulley is on a lay shaft, not on the crankshaft.
The YSB has an ally gearbox and the YSM an ally gear box, front pulley on the crank, and a different fuel pump.
I have read, and been told NOT to run the engine slowly for any length of time, as it will quickly wear out. As it is raw water cooled, and 80% of engine wear occurs in the warm up, usually around 10 minutes, this makes a lot of sense. Also, having a heavy piston on it's side, I suspect the oil scavenging will be insufficient to keep the rings from wearing on the bore at the bottom.
I have had to rely on what I have been told, by others supposedly with experience, so if I am mistaken, or anyone can add to this, please do so.
<hr width=100% size=1>Malcolm.
<A target="_blank" HREF=http://www.angelfire.com/rnb/malcsworld/>http://www.angelfire.com/rnb/malcsworld/</A>
Take a look at my boating pages.
The name plate on the clutch housing was missing, making identifying it a real pain.
This is what I have been told, by experienced mechanics, and others have backed this up. It may not be 'gospel' but I think the facts are correct.
The engine was designed as a flat twin in the middle of the 1930s by Coventry Climax.
Yanmar made the engine from half of it making the YSE from 1974 to 77, YSB from 77 to 78 and YSM from 78 to 80.
The manual I downloaded says the YSE is 3 to 1 reduction and the others 2 to 1, but YSEs can be 3 or 2 to 1, so I expect this may apply to them all. Mine is a 2 to 1 reduction, and the engine runs at 3000rpm, so the shaft 1500.
The YSE has a cast iron gearbox, and the front pulley is on a lay shaft, not on the crankshaft.
The YSB has an ally gearbox and the YSM an ally gear box, front pulley on the crank, and a different fuel pump.
I have read, and been told NOT to run the engine slowly for any length of time, as it will quickly wear out. As it is raw water cooled, and 80% of engine wear occurs in the warm up, usually around 10 minutes, this makes a lot of sense. Also, having a heavy piston on it's side, I suspect the oil scavenging will be insufficient to keep the rings from wearing on the bore at the bottom.
I have had to rely on what I have been told, by others supposedly with experience, so if I am mistaken, or anyone can add to this, please do so.
<hr width=100% size=1>Malcolm.
<A target="_blank" HREF=http://www.angelfire.com/rnb/malcsworld/>http://www.angelfire.com/rnb/malcsworld/</A>
Take a look at my boating pages.
