yanmar 1GM

[chuck]

I have a 1994 25D with the yanmar 1GM diesel
HEAVY smoke at 2800plus rpm
Boat has a 12x12 2 blade prop
Anyone having or had similar problems ?



cgombeski@aol.com

[mark mel]

I have a 1994 25D with the yanmar 1GM diesel
HEAVY smoke at 2800plus rpm
Boat has a 12x12 2 blade prop
Anyone having or had similar problems ?

Make sure the prop and bottom are clean.



mmelaragno@aol.com

[john vigor]

Chuck, it sounds as if you're overpropped. The standard three-bladed prop for the 1GM in a 25D is 12 inches diameter by 9 inches pitch. To compensate, a two-bladed prop would need about another inch of pitch, making it a 12 by 10. Your 12 by 12 will push you along nicely at low revs in calm water, but you won't be able to reach the engine revs you need to develop full power in adverse conditions. The coarseness of the pitch will load the engine unfairly and cause it to eject unburned fuel in the form of black smoke. You should be able to top out at (or a little over) 3,400 rpm, and run all day at a little over 3,000, with a smaller-pitch prop--and you'll be able to use every one of those precious 7 horses. Any decent prop shop can reduce the pitch of your prop by 2 inches for $50 or less.

John Vigor
CD25D "Jabula"



jvig@whidbey.net

[Bill]

John

I am curious about the cost of a 3 bladed prop for my 25D. Can you give me a ball park figure?

Thanks

Bill
<a href="http://www.rhapsodysails.com/sailing.html">Rhapsody's Cyber Slip</a>

Chuck, it sounds as if you're overpropped. The standard three-bladed prop for the 1GM in a 25D is 12 inches diameter by 9 inches pitch. To compensate, a two-bladed prop would need about another inch of pitch, making it a 12 by 10. Your 12 by 12 will push you along nicely at low revs in calm water, but you won't be able to reach the engine revs you need to develop full power in adverse conditions. The coarseness of the pitch will load the engine unfairly and cause it to eject unburned fuel in the form of black smoke. You should be able to top out at (or a little over) 3,400 rpm, and run all day at a little over 3,000, with a smaller-pitch prop--and you'll be able to use every one of those precious 7 horses. Any decent prop shop can reduce the pitch of your prop by 2 inches for $50 or less.

John Vigor
CD25D "Jabula"

cd25d@rhapsodysails.com

[HDHarris]

I strongly recommend that you get that prop properly sized, balanced and fitted. I paid $75 in Ft. Myers, Fla. to have my trimmed and balanced for my Yanmar 2GM20. The mechanic and the local Yanmar rep. said if the prop is not sized right, then your engine will not properly operate, and in some cases, if the prop is too big (like mine), it will cause very heavy carbon deposits to build up inside the cylinders, on the valves and maybe even on the fuel injectors - A VERY EXPENSIVE REPAIR/REBUILD PROPOSITION!!

Get the prop properly trimmed, balanced and fitted - it's much easier than engine repairs.

Regards,

HDHarris
S/V Aguila CD28



HDHarris@juno.com

[john vigor]

Bill,
A new three-bladed 12-inch bronze prop would cost in the region of $250 to $300. The 1999 M&E Marine catalog lists a standard three-blader for $256. Prop shops often sell reconditioned used props for half that price, so it may be worth checking the web or your local propeller shops.

John V.

John

I am curious about the cost of a 3 bladed prop for my 25D. Can you give me a ball park figure?

Thanks

Bill
<a href="http://www.rhapsodysails.com/sailing.html">Rhapsody's Cyber Slip</a>

jvig@whidbey.net