Replacement of a Yanmar 1gm
- Thread starter Marijo
- Start date
Marijo, it looks like a pretty easy swap. The distance from the rear engine mount to the propeller shaft flange is the same, as is the vertical distance from the mounts to the center of the output flange. The width between mounts is the same as is the depth below the mounts.The question is whether you have enough room going forward on the stringers. The 2GM is 2.5985 inches longer between the two mounts (fore/aft) and 1.22 inches longer in front of the front mounts. The 2 GM is taller from the mount to the top by less than an inch without the humped exhaust elbow. To summarize, you would mount the rear of the engine in the existing location; then you'd need to be able to move the front mounts forward by 66mm.. and you'd need an additional total room of 97mm (say 4") forward measured from the aft engine mounts, passed the front of the existing engine. If you have that space, it can be done.
Why?
A 1GM10 should be able to drive your boat to or near hull speed. More power is just a waste.
Could you describe the problem you are trying to solve?
A 1GM10 should be able to drive your boat to or near hull speed. More power is just a waste.
Could you describe the problem you are trying to solve?
I'll try to explain. This is a new experience for me and I am not familiar with technical aspects of motoring.
The engine is 25 years old, according to the preceding owner.
My problem is that when I run the engine at 3000 rpm, the maximum speed I can reach is 4,2 knots. If I understand correctly the hull displacement formula, I should be able to reach near 6 knots (6,3 in fact).
So I figured out that if the engine is probably close to the end of it's life, should I replace it with a more powerful engine.
But if I understand your comment, it would not give me more speed with a 2gm, right?
Thank you for your time,
Jocelyn
Jocelyn,
That engine is underpowered for the displacement of your boat. That said, you might look into whether a different prop would help. What kind of prop is on there now? You could check with a prop shop to see if you have the right one. Assuming your engine is putting out its rated HP, a change in prop could make a substantial difference, depending on what you currently have.
A 1GM10, with the correct prop, should get you at or close to hull speed in calm water. With any kind of sea action or wind it will not because the engine is undersized for that boat. I have a 1GM (not the 10) in my Ericson 26, which displaces less than you, and it is barely good enough. A bigger engine would give you some reserve, but if you can increase the performance of what you've got you may find it good enough. Repowering is hugely expensive and a big hassle. Plus the 1GM10 is a good little engine. You could get the prop taken care of for very little money and you might be satisfied with the result.
Check prop and engine
At 3,000 RPM, a good prop should drive you around 5.5 to 6.0 knots in calm wind/water. So definitely check your prop. If you are getting the RPM's, the prop is not doing its job.
I'd also have a good diesel mechanic check your engine before the major expense of buying and installing a new engine. If the compression is still good, it should generate the power you need, regardless of its 25 years.
Find the real cause of your problem, then the solution will come quickly. And lots of the possible solutions are less time and money than repowering.
At 3,000 RPM, a good prop should drive you around 5.5 to 6.0 knots in calm wind/water. So definitely check your prop. If you are getting the RPM's, the prop is not doing its job.
I'd also have a good diesel mechanic check your engine before the major expense of buying and installing a new engine. If the compression is still good, it should generate the power you need, regardless of its 25 years.
Find the real cause of your problem, then the solution will come quickly. And lots of the possible solutions are less time and money than repowering.
You might also want to have your transmission checked. My 1GM10 was a new refit in 2005, and easily reaches 3000+ rpm, but I can get nowhere near hull speed in calm waters. I found out a PO had used ATF fluid in the transmission, but it's supposed to use the same oil as the engine. The tranny for the 1GM10 uses a cone clutch, and mine has become glazed due to the ATF fluid. It therefor doesn't engage fully unless I push down hard on the shifter. A rebuild is on the calendar for January!
I say stick with the current set-up, change your fluids, and check your prop size. Is your bottom clean? Parasitic drag can slow you down.....does your boat reach hull speed while sailing in a stiff breeze??????..........
Outcome for Replacement of a Yanmar 1 GM
First of all, Thank you very much for all your advices. I really appreciate your guidance and it was helpful to the mechanic I hired last week. He took the compression of the cylinder and it was fine. He checked the fuel pump and everything was ok. He sent some engine oil to a laboratory for a diagnosis and we are waiting for the report. So the next thing to do is check the prop and the bottom of the boat. I will hauled the boat out of the marina in a couple of weeks, so I will be fixed about that too.
Again, thank you all for your guidance. I really appreciate.
Jocelyn