Replacing a Yanmar YSE12 with ???

eebygum

eebygum

Well-Known Member
Joined
6 Nov 2002
Messages
568
Location
Manchester
Visit site
I’m looking to replace the original YSE12 in a SHE 32.... I’ve read previous/similar threads and I’m quite keen on a reconditioned BETA 20hp but I need to keep costs down.

Will I be able to use the original shaft and propellor or need to replace ?

Is there a better replacement option which would use the same shaft and propellor or fit on the existing engine beds ?

All information gratefully received.

Many Thanks
 
I once swapped out a YSE for a Vetus/Mitsubishi.
From memory, the YSE engines use a LH prop. so will not suit most modern engines, inc. Beta. No reason not to re-use the shaft if the length is OK and the prop. taper is matched, but yours will be old/worn(??) and new is not too expensive in re-engining terms. You will also need a suitable coupling.
I think the Yanmar mountings will be longer and wider than the Beta so some modification will be needed, but probably not too expensive/difficult.
You will need to enlarge the c/w intake if it's currently 1/2". The exhaust size is probably also different.
A new single lever control and cables will also probably be needed.
 
Last edited:
eebygum said:
I’m looking to replace the original YSE12 in a SHE 32.... I’ve read previous/similar threads and I’m quite keen on a reconditioned BETA 20hp but I need to keep costs down.

Will I be able to use the original shaft and propellor or need to replace ?



Is there a better replacement option which would use the same shaft and propellor or fit on the existing engine beds ?

All information gratefully received.

Many Thanks
Click to expand...

Why do so many people try and make the engine suit the propeller?
It’s the propeller that allows that converts the power produced by the engine into thrust to drive the boat so get the best fit possible
If the old prop is correct for 12hp(actually more like 9) it’s not really likely to be correct for 20 hp
The shaft may also be an unsuitable diameter
 
20 years ago I replaced a Yanmar YSE12 with a Volvo 2020 in a cobra 850. As I remember it was a little overpowered but ok. We also had to replace the exhaust pipe, possibly because it was knackerd as I think we reused the waterlock and skin fitting. At the same time we replaced the fuel tank filter and pipework because not only was it a bit rusty but to replace it later would mean the engine coming out again. We had to replace the prop for a different size, we retained the old shaft and added a dripless gland, we also had to replace the cutlass bearing because of wear and the sterntube as it had become dezinctified. Whilst the old engine was out we cleaned,painted and soundproofed the engine bay. New cables and morse control and new pipework for the calorifier. New seacock and pipework for the engine with a strainer. We also fitted a halyard aquadrive. As I remember the original engine bearers were the correct distance apart and height to slot the engine straight in.
It was probably a bit over the top but I did all the work myself which saved us considerably and we ended up with a reliable quiet and smooth engine which with a young family not only gave us an easy time but gave us the confidence to go much further afield without the fear of the old engine conking out as it had done regularly before.
 
Most issues covered already. There is nothing modern that is a direct replacement, but there will be plenty of room in the bay for what will almost certainly be a smaller engine. The critical point is the coupling on the shaft as this is a fixed point so you build your bearers and mounts from there. If you buy Beta there will almost certainly be a set of fabricated brackets available from Beta to mate the engine to the Yanmar bearers.

As said you will need a new propeller. You may be able to reuse the shaft if it is not worn unless it is bronze, which in a 1" size will be insufficient for 20hp. However a stainless shaft is not a lot of money in relation to your overall cost. You will need new controls as any modern engine needs single lever Morse controls.

As to what you can re-use, that depends on condition. Remember all the bits (exhaust, shaft seal, fuel system, electrics, plumbing etc) will be 40 years old and it is false economy to re-use old bits with a new engine. Best to strip the engine bay bare, clean it paint and install insulation. Then start as if you are going to do a complete new installation, even if you use a secondhand engine. You only want to do the job once.
 
How do? I'm also from the land of Eebygum, Halifax. I also have a Yanmar YSE12 that came with a Colvic UFO 31 I bought for restoration and is also in need of either some serious work, or replacement and I was wondering if you might have found a good solution to the problem?
 
I fitted a new Beta 16 to replace a Yanmar 2020. The Yanmar was more 18hp, While the Beta is actually 16 hp. Beta supplied a flex coupling for the shaft and we retained the original prop, shaft & water lift and inlet. The only oddity was the flex mountings. Required spacers to get the new ones up to a level where they suited the engine. The Morse control worked backwards for forward and reverse, but that is easy to change..
Biggest hassle was routing the wiring harness, but that was particular to the boat. Probably fitted on assembly with no consideration to replacing.
 
The later Yanmar 2GM (which I think is what you mean) is a very different engine from the YSE which is a single cylinder horizontal, low revving engine, solid mounted. Prop shafts are often bronze which are not recommended for more powerful new engines (and often knackered but fetch a good price at the scrappy) and controls are either stick gear change and motorcycle style throttle or 2 lever type. Water intake is 1/2" rather than 3/4" and exhausts often don't have waterlocks. Big plus though is that there will be enough space to fit either a 16 or 20 Beta.
 
Tranona said:
The later Yanmar 2GM (which I think is what you mean) is a very different engine from the YSE which is a single cylinder horizontal, low revving engine, solid mounted. Prop shafts are often bronze which are not recommended for more powerful new engines (and often knackered but fetch a good price at the scrappy) and controls are either stick gear change and motorcycle style throttle or 2 lever type. Water intake is 1/2" rather than 3/4" and exhausts often don't have waterlocks. Big plus though is that there will be enough space to fit either a 16 or 20 Beta.
Click to expand...
Yes, 2GM20. Very different from the YSE. But thought I would throw it in. The conversion was easy, just the mountings needed some alteration..
 
Abbo 21 said:
How do? I'm also from the land of Eebygum, Halifax. I also have a Yanmar YSE12 that came with a Colvic UFO 31 I bought for restoration and is also in need of either some serious work, or replacement and I was wondering if you might have found a good solution to the problem?
Click to expand...

Abbo 21 said:
How do? I'm also from the land of Eebygum, Halifax. I also have a Yanmar YSE12 that came with a Colvic UFO 31 I bought for restoration and is also in need of either some serious work, or replacement and I was wondering if you might have found a good solution to the problem?
Click to expand...
Nowt wrong with an old YSE12 if it’s been looked after.

Commenting on my original posting, I kept the YSE12 engine in my SHE 32 and it served me very well without failure in the end. Would easily hand start once you learnt the knack. Maintenance was a doodle.

By today’s standards you would say the boat was underpowered but 12hp is more than enough… I circumnavigated Ireland and went to the Faroe Islands with the little gem as my auxiliary engine.
 
eebygum said:
Nowt wrong with an old YSE12 if it’s been looked after.

Commenting on my original posting, I kept the YSE12 engine in my SHE 32 and it served me very well without failure in the end. Would easily hand start once you learnt the knack. Maintenance was a doodle.

By today’s standards you would say the boat was underpowered but 12hp is more than enough… I circumnavigated Ireland and went to the Faroe Islands with the little gem as my auxiliary engine.
Click to expand...
Brilliant. My engine is not looking like it's been looked after too well, so I think she's going to need a full refurb to get her going again. There's an element of risk as we don't know what's causing an oil leak just yet but fingers crossed it's nothing too serious. Changing to a different engine is going to get complicated but the initial refurb is looking expensive. Fortunately didn't pay too much for yacht, so we could manage the repairs ok.
 
Abbo 21 said:
Brilliant. My engine is not looking like it's been looked after too well, so I think she's going to need a full refurb to get her going again. There's an element of risk as we don't know what's causing an oil leak just yet but fingers crossed it's nothing too serious. Changing to a different engine is going to get complicated but the initial refurb is looking expensive. Fortunately didn't pay too much for yacht, so we could manage the repairs ok.
Click to expand...
For my Faroes trip I actually purchased a complete YSE12 as a spare off eBay for £350. I left it in my garage and my thinking was that if I needed anything (alternator, lift pump, water pump etc) my brother who is an engineer would take it off and send to me.

As an insurance policy it was much cheaper that way as individual parts are hard to come be and expensive.

As if was the engine worked perfectly and the spare wasn’t needed. I subsequently sold it back on eBay for only slightly less than what I paid for.

They do still come up occasionally so worth buying a good one for potential spares.
 
You must log in or register to reply here.

Share this page

Top