Yanmar 1GM-10

[stick]

Dear all. Has anyone suffered the same? Out of gear, engine attains full RPM ahead or astern. In gear, engine attains full RPM astern but only 50%(200) RPM ahead.Work done so far.New prop shaft,cutlass bearing,inboard bearing, flexi-coupling, engine mounts.Re-built high pressure fuel pump and injector,fitted new fuel /air filters,done oil changes. /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gifI have tried operating engine with cables disconnected but still no good.

 

[alan17]

My immediate thought is over size prop.

More info needed re size and type of prop and gearbox ratio in both F & R

 

[retsina]

Did you match the prop to the engine? is the prop the correct direction of rotation?

 

[Pye_End]

Could be fuel system or air system as well!

 

[Honey]

Ratios for the standard 1GM gearbox are ahead / rev :- 2.21/3.06 - 2.62/3.06 - 3.22/3.06. Therefore whilst a lot depends on which gearset you have, it does sound as if Captain_Fantastic may be on to something unless you have the last set of gears as above. More details as to which ratios you have are needed.

 

[Pye_End]

Yes, but - it is unlikely that reverse is putting that much load on the engine, so although they are reasonable comments, it can also be a lack of power generation from the engine.

 

[Bilgediver]

Could you tell us more......

Is this a new installation or has something recently been changed or is it the same old engine and bits and last year worked fine????

Are these readings taken tied up at the pontoon or underway?

 

[steve28]

are you getting black smoke when going ahead ?
Are you sure its a 1gm10 and not a 1gm engine. this would make a subtantial diffrence in prop size.

steve

 

[stick]

This is the original prop engine and gearbox,which was working perfectly ok. I get a little black smoke when i try to continue throttle up past the 200 RPM mark. Regards Stick.

 

[Bilgediver]

Did you check the exhaust mixing outlet??????????

SOmetimes these get choked!!