Yanmar YSB 12 Starting

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djyacht

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I `ve just bought a boat equipped with this single cylinder motor. It`s a pig to start (when it does) and I`ve read a lot of advice on the site and elsewhere. The fuel on board (approx. 12 gallons) I know is elderly, at least 4 years, and I`m wondering if before taking injector out etc. it would be worthwhile removing all the existing diesel and putting fresh in?

Thanks

David
 
djyacht said:
I `ve just bought a boat equipped with this single cylinder motor. It`s a pig to start (when it does) and I`ve read a lot of advice on the site and elsewhere. The fuel on board (approx. 12 gallons) I know is elderly, at least 4 years, and I`m wondering if before taking injector out etc. it would be worthwhile removing all the existing diesel and putting fresh in?

Thanks

David
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there is an oil injection cap in the inlet manifold for cold start, a squirt of engine oil should do the trick.

if you have fuel,air & compression it will start.
your fuel in the tank will be ok
there is a plastic washer/gasket under the injector face, if you remove the injector this MUST be replaced.
 
Diesel shouldn't degrade, but perhaps 4 years is pushing it. Can you rig up a small temporary tank to avoid ditching ~£60's worth of fuel?
Those YS engines are fairly good starters, get it spinning as fast as possible on motor or handle before dropping the decompressor.
At that age howeve, a few things could be less than perfect, but they are easy to work on. Taking the injector out to check the spray isn't difficult, but other things like valves, ring/bore wear affecting compression are possible suspects.
 
earlybird said:
Diesel shouldn't degrade, but perhaps 4 years is pushing it. Can you rig up a small temporary tank to avoid ditching ~£60's worth of fuel?
Those YS engines are fairly good starters, get it spinning as fast as possible on motor or handle before dropping the decompressor.
At that age howeve, a few things could be less than perfect, but they are easy to work on. Taking the injector out to check the spray isn't difficult, but other things like valves, ring/bore wear affecting compression are possible suspects.
Click to expand...

i rebuilt ours, new liner & rings are easy to do with the engine out. i had a paint job done at the same time
 
sailorman said:
i rebuilt ours, new liner & rings are easy to do with the engine out. i had a paint job done at the same time
Click to expand...

I did similarly, mine was a YSE8, a bit smaller than the 12 perhaps, but it was possible to dismantle it "in-situ" into parts light enough to be picked up and carried down a ladder single handed to take home!
The only bit I had real trouble with, as I remember, was separating the flywheel from the crankshaft.
After that work, the pool of oil on the water at start-up ceased to appear.
 
I laid up a diesel powered VW van for seven years while we were abroad. On our return it started first time and ran perfectly on the 10 gallons or so in the tank.

It could be worth checking that fuel is being drawn into the engine, not water that is lying below the diesel in the bottom of the tank.
 
As it's new to you and the history isn't known, I'd recommend a top end overhaul this winter. You can get the injector and fuel pump serviced by professionals at the same time. It's surprising how effective it is to lap the valves in and set the tappets correctly.

Spinning up the engine with the decompressor on gives an additional squirt or three of diesel which rather negates the need to use the oil injection cap on the manifold.

Another thing to check while you're about it is the air cleaner.

When the head is off you can also check out the manifolds. I"m not sure if this one suffers from salt water ingress but it's quite common for 1GM10 heads to rot when the mixer elbow fails and salt water finds its way into the exhaust manifold.
 
Topcat47 said:
As it's new to you and the history isn't known, I'd recommend a top end overhaul this winter. You can get the injector and fuel pump serviced by professionals at the same time. It's surprising how effective it is to lap the valves in and set the tappets correctly.

Spinning up the engine with the decompressor on gives an additional squirt or three of diesel which rather negates the need to use the oil injection cap on the manifold.

Another thing to check while you're about it is the air cleaner.

When the head is off you can also check out the manifolds. I"m not sure if this one suffers from salt water ingress but it's quite common for 1GM10 heads to rot when the mixer elbow fails and salt water finds its way into the exhaust manifold.
Click to expand...

i tried to get my injector pump serviced. they were not able to do it
being a flat engine therefore the cylinder is quite low & prone to water ingress & it all ends up laying in the bore at the bottom
 
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I removed both injector and pump and took them to Panda in Fareham when I did my top end overhaul.

The pump can't really be serviced in situ. I'm not sure about the relevance of the engine being "flat". The only horizontal engine I've worked on was an Enfield boxer twin. The injectors and pump was on the upper casing. Surely Yanmar didn't fit it underneath?
 
My yse8 had stood for 12 years before I replaced the head gasket and rings. Started quite happily with the diesel I inherited in the boat. Bit diluted now but there will be some of it still there.
Just found out it would have cost the previous owner about 68p per litre assuming its not the red stuff

The head is a straightforward job to remove from that engine and if you can get to the 'sump' cover on the other end (behind the alternator) then you can undo the big end and push the piston out.

If I need to work on the engine again I will do it without taking the engine out of the boat.


Parts ain't cheap (including gaskets, bolts, pipes etc) but its a beautifully simple engine and I reckon bulletproof.

Get your parts and advice from John at Cellar Marine, a great advocate for an engine reputed to come up still running if it fell out of the boat
 
A common problem on old YSBs is a worn needle in the fuel pump. At the front of the engine is an L shaped lever tensioned by a spring which is part of the governor mechanism. Try pulling this lever out against the spring tension whilst cranking the engine, release it if the engine starts.
 
YSB Engine starting

Can I say a big thank you to all who responded to my original post and offered advice. I have lots to be going on. This thread illustrates (IMHO) exacly what a good forum is about -thanks again to all.


David
 
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