upgrade from Yanmar 1GM10 to 2GM

[dave_gibsea]

Hi,

Well, my 34 year old (OEM)1GM10 Yanmar is still giving good service but uses a bit of oil now. I always felt the boat was a tad underpowered so I was considering an upgrade to a 2GM. Has anyone done this? If so how straightforward is the swap?

Thanks, Dave

 

[scottie]

Have you room for bigger propeller and is rest of stern gear up to it

 

[B27]

Have you room for bigger propeller and is rest of stern gear up to it

That would be my question too!
What will the gear ratio be?

If you're thinking of a fixed prop, you may end up with a big prop which has the proverbial drag factor of a bingo hall, making your boat sail like a three legged dog.
A bigger engine is very nice, if you can fit a folding or feathering prop, which can be a problem as a big enough two-blade might not fit and other options are a bit fierce on the credit card.

 

[Tranona]

2GM is now a very old engine so you will have to look for a good used one. The only real mod is extending the engine beds forward possibly to take the greater length and possibly rebuilding the engine box. The gearbox is the same but you will need a new propeller. Watch the ratios if you do change the box as there are 3 choices.

However doubling power is not normally a good idea and the best replacement for a 1GM is a Beta/Nanni 14 which fits almost without mods - just different spacing for the engine mount bolts, a new coupling on the shaft and a conversion exhaust to link up with your current system if you can't move it to the other side. again you will need either a new propeller or a repitch depending on the ratio you choose.

 

[LittleSister]

I can't see the point in replacing an 'earlier generation' engine that is tired but giving good service with another 'earlier generation' engine, especially if, as presumably will be the case, it is of unknown condition. (It, too might use oil, or worse.)

I feel the additional power is a distraction. (And as Tranona suggests is probably more than you want.) The existing engine power, even if not ideal for modern tastes, has sufficed for 34 years.

The changeover will cost money, time and uncertainty (there are always complications), but you will still have an old engine which is more likely to require attention, and should you want to sell the boat will still be a minus point.

If you are on a budget, why change? If you could afford a modern, suitable power output replacement at some point, that would be a better move on a range of fronts.