Yanmar1gm rebuild

[Steviecracknell]

The engine has blown the rings, and the bore is worn by 0.2mm at tdc, is the engine now scrap or can it be rebuilt. Does anyone know if the block can be fitted with a liner, just like the 1gm10 has. It would be good to repair this engine, as it is perfectly sized for my boat.

Cheers Stevie.

 

[tonygibbs]

I would imagine that the block could be re-bored to take oversized pistons. Might be worth considering getting the crankshaft reground and fit a new camshaft and bearing shells.

 

[dave_gibsea]

Hi Stevie,

I rebuilt my 1GM10 4 years ago, it was 20 years old at the time. I got a lot of good advice from Peter at Marine Power, we needed a hone and new rings. The head had corroded badly so a new head and exhaust mixer/manifold too and a set of gaskets, that was prettty much it but the cost was close to £1,000 at the time. The rebuild was easy, if you have ever rebuilt a car or motor-cycle engine it is very simple by comparison but the spares costs are horrific so I would suggest you look on the web and estimate the cost before you start. You may find the parts come to half way towards a new engine not counting your labour of course. The other consideration is you won't have a new engine afterwards, things like the starter motor, alternator etc could need replacing in future.

My advice would be that you have to be honest with yourself, if you are confident with the project and the budget makes sense go for it. I think the rebuld took me a few hours - a day at most. If you haven't previous experience or are considering paying a mechanic's labour, or you you don't fancy it then look for a replacement.

Cheers,

Dave

 

[Steviecracknell]

Dave, the rebuild isn't a problem, its whether the 1gm can be rebuilt or not.
I haven't found any information on the internet regarding a cylinder rebore, I think this is the engines achilles heal. I'll make some enquiries regarding an oversize piston, and give Marine power a call to see if its possible.
While i'm on the subject, I would be looking for a replacement 1gm10 engine if you know of anybody selling one.

Cheers Stevie.

 

[25931]

Dave, the rebuild isn't a problem, its whether the 1gm can be rebuilt or not.
I haven't found any information on the internet regarding a cylinder rebore, I think this is the engines achilles heal. I'll make some enquiries regarding an oversize piston, and give Marine power a call to see if its possible.
While i'm on the subject, I would be looking for a replacement 1gm10 engine if you know of anybody selling one.

Cheers Stevie.

When faced with the same problem we bought a Beta which is near enough the same size and everything is new and up to date, more efficient and quieter.

 

[Tranona]

Dave, the rebuild isn't a problem, its whether the 1gm can be rebuilt or not.
I haven't found any information on the internet regarding a cylinder rebore, I think this is the engines achilles heal. I'll make some enquiries regarding an oversize piston, and give Marine power a call to see if its possible.
While i'm on the subject, I would be looking for a replacement 1gm10 engine if you know of anybody selling one.

Cheers Stevie.

Suggest you talk to Cellar Marine who probably know more about rebuilding these engines than anyone. I am assuming you have an original 1GM rather than the later 1GM10. Relatively few of those were made and there are differences between the two models.

Not many 1GM10s come on the secondhand market. When I sold mine the phone started ringing within hours of the ad going on line and I had a queue waiting to buy it. Boats and Outboards is a good place to look. If you are going down the new route then as 25931 suggests a Beta or Nanni 10 is a far superior choice and is as close a direct replacement as you can get as the footprint is virtually the same, just 1cm longer and a bit bulkier at the back because of the extra cylinder. Refinement is in a different league.

 

[30boat]

Suggest you talk to Cellar Marine who probably know more about rebuilding these engines than anyone. I am assuming you have an original 1GM rather than the later 1GM10. Relatively few of those were made and there are differences between the two models.

Not many 1GM10s come on the secondhand market. When I sold mine the phone started ringing within hours of the ad going on line and I had a queue waiting to buy it. Boats and Outboards is a good place to look. If you are going down the new route then as 25931 suggests a Beta or Nanni 10 is a far superior choice and is as close a direct replacement as you can get as the footprint is virtually the same, just 1cm longer and a bit bulkier at the back because of the extra cylinder. Refinement is in a different league.

On top of that the original 1CM only put out 7hp.a bit puny.

 

[mickywillis]

I have a 1GM10 bottom end that's in good condition if it helps. I can take pics and email them to you if required. reason I have it is it was brought as a non runner (cylinder head failure) and I wanted the gearbox from it. Only downside is I'm in Epsom in Surrey.
PM me if you wish to discuss (wouldn't want a huge amount for it)
May be a cheap way to get yours up and running again (for the price of a complete gasket set, the bottom end and transport costs) plus your time, but an excellent learning curve.

 

[Steviecracknell]

Thanks for the offer Micky, but after some consideration, I think I will pursue a decent beta engine as suggested.
The 1gm engine was removed from the boat tonight with the help of the boom, block and tackle, and a calm sea, surprised it went very smoothly, would recommend this approach if you had to remove your 70kg ish lump.

 

[Tranona]

You need to be careful with your choice of 10hp engine as it runs at lower revs than the Yanmar and is usually fitted with a 2:1 reduction giving a shaft speed of 1500rpm (although there is an option of 2.65). Yanmar has a choice of reductions giving shaft speeds of 1200, 1400 or 1600 (all approx) You may well find you need a bigger prop to absorb the extra power. You will also need to modify the exhaust as the pipe diameter is different and fit a larger 3/4" water intake. Packing required on the engine beds as the mounts are higher in relation to the gearbox output. May also need longer control cables. Otherwise a fairly straightforward swap.

 

[JumbleDuck]

Packing required on the engine beds as the mounts are higher in relation to the gearbox output.

I thought Beta undertook to match your existing mountings ... or is that spacing only and not height?

 

[Tranona]

The width of the beds is virtually the same (5mm more from memory) but the mounts are further apart fore and aft so need new holes in the beds. I put a 15mm or so pad on the top of my beds otherwise there would be no vertical adjustment. The mounting brackets Beta and Peachment offer are for replacements of old engines like Volvos and BMC where the beds will be much further apart. They are usually steel frameworks you bolt to the wider beds and have positions for the new mounts.

You need to look at each boat individually as there are lots of variations - for example the boat my 1GM went into had assymetric beds to take a Petter with an offset output. The owner put in new beds rather than hack about the old ones.

 

[JumbleDuck]

The width of the beds is virtually the same (5mm more from memory) but the mounts are further apart fore and aft so need new holes in the beds. I put a 15mm or so pad on the top of my beds otherwise there would be no vertical adjustment. The mounting brackets Beta and Peachment offer are for replacements of old engines like Volvos and BMC where the beds will be much further apart. They are usually steel frameworks you bolt to the wider beds and have positions for the new mounts.

You need to look at each boat individually as there are lots of variations - for example the boat my 1GM went into had assymetric beds to take a Petter with an offset output. The owner put in new beds rather than hack about the old ones.

Thanks. When I asked at the Beta stand at a boat show I thought they said they could provide feet which exactly matched my 1GM10 feet, but perhaps I misunderstood. For the moment the Yanmar soldiers on, anyway, and when I do eventually replace it I don't think it will be a Beta ... too many stories of problems here. Do many people get 25+ years out of a Beta?

 

[Tranona]

Expect you could have fabricated adaptors to go from the Yanmar spacing to the Kubota,which might be useful if you have metal beds, but easier to just drill new holes if you have wooden or wood core beds. Mine are screwed down with 3" M12 coachscrews into oak with a ply capping to raise from the original stuart Turner beds.

Beta haven't been around for that long, but see no reason why they should not. Get a blue version of a Kubota instead as it seems to have a better heat exchanger which is where most of the Beta criticism comes from. Will let you know in 25 years time how I get on.

BTW most of the "stories" regarding engines are about Yanmars, Volvos and Betas - not surprising as they collectively account for probably 80%+ of the small diesel market.

 

[JumbleDuck]

Haven't been around for that long, but see no reason why they should not. Get a blue version of a Kubota instead as it seems to have a better heat exchanger which is where most of the Beta criticism comes from. Will let you know in 25 years time how I get on.

Yes, there does seem to be less adverse about Nanni, though perhaps that reflects a smaller market share. I'd be delighted if the 1GM10 survived another 25 years, but I am not quite that optimistic. We'll all be on fuel cells and electric motors then anyway ...

 

[Steviecracknell]

I have abandoned the idea of a beta replacement, but wouldn't rule it out in future.
Thanks Tranona for the Cellar Marine tip off, I have just priced the cost of a bottom end rebuild, and it totals 600 quid, very tempting, especially when they can rebore the 1gm out to the 1gm10 spec, which equates to extra horse power. I am still undecided.

 

[LittleSister]

Beta haven't been around for that long, but see no reason why they should not. Get a blue version of a Kubota instead as it seems to have a better heat exchanger which is where most of the Beta criticism comes from. Will let you know in 25 years time how I get on.

Beta have 'only' been around for 27 years! I don't think the heat exchanger is too bad myself (design now changed anyway, I think I read), and they are very good on spares and advice (which is not what I've heard about the Nanni importers, though the Nanni engine is also good). Beta will make up mounting brackets to mount their engine directly to your beds. (No connection except satisfied customer.)

 

[30boat]

Beta have 'only' been around for 27 years! I don't think the heat exchanger is too bad myself (design now changed anyway, I think I read), and they are very good on spares and advice (which is not what I've heard about the Nanni importers, though the Nanni engine is also good). Beta will make up mounting brackets to mount their engine directly to your beds. (No connection except satisfied customer.)

I've taken the tube stack out on my 2003 Bet BD722 and the heath exchanger shows no signs of corrosion despite my not having been exactly fastidious with anode replacements.