yanmar 2gm20

[Johnboy2004]

hello i am looking at buying a 21 foot second hand boat. she is powered by a yanmar 2gm 20.. is this engine powerful enough to move her along at a decent speed without over working the engine?

also id like to hear from someone that has a 2gm20 yanmar engine...

what are the most common faults with these engines?

the boat i am looking at has been lying idle on the water for 1.5 years , with no engine use except for ocasional engine starts..... would this have damaged the engine in any way? there is only 40 hrs on the engine and she is 4 years old....
do i need to get her surveyed?
what speed would i expect the 2gm20 to push this boat at? it is a displacement hull...
cheers for the help

 

[ShipsWoofy]

18hp from the 2GM should push your 21ft'er to hull speed with reserve.

Worst thing you can do to a diesel is not work it. You will probably be lucky, but before taking her out, I would consider changing the oil and filter and definitely changing the raw water impeller (they do not like sitting stationary to long). Also have a good look or feel underneath the engine for corrosion as it has been in a cold damp environment, not a good combination.

Most common faults with yanmar are stripping alternator belts and eating impellers. Otherwise they are agricultural beasts designed to plod along forever.

Hull speed in knots= 1.33 times the square root of the waterline length in feet. so lets say 18ft waterline = 5.66 kts

hope that helps a bit....

 

[capricorn]

I have this engine.

Generally it has a sound reputation.

A common fault is that the exhaust mixing elbow will get coked up after a few years. This is easily and cheaply replaced but if unaddressed the coking up will extend to the exhaust port causing a restriction that in extreme cases can require reconditioning of the cyclinder head.

Excellent resource for this and other yanmar engines here, www.yanmarhelp.com the forum is run by a marine engineer called Dave who is immensly knowledgable and helpful.

 

[fireball]

We've got a 2gm20 on a SO30 - at 3.5T, pushes us along with no problem...
We had a 22' long keel - and put a Volvo MD5a in (5hp) and that pushed that boat along with no problem too ... 18hp in a 21' ... fit hydrofoils!!

 

[Colvic Watson]

That really is one hell of an engine for a 21 footer. Would suggest that when you drain the engine oil you also flush as well. I know it has only 40 hours but it sounds like what's in there has been sitting for a while. Definitely change the impeller.

Even more important is the fuel. If she has been sitting there for a while with a half full fuel tank you may well have some water condensation in the tank and/or bugs in the fuel. Drain the tank, flush the lines, change the fuel filters and check the fuel/water separator.

Still, a superb engine that would have cost about £4,500 fitted.

 

[paulrossall]

I have a 30foot boat and my 2GM20 is slightly underpowered for the weight of the boat. It should be more than enough for you. Alternator belts do wear but my engine starts and runs very well indeed...could not be better or more reliable. IMHO. Paul

 

[upcountry]

Look for a letter prefix on engine identification plate. Isay this because i have a 2GM 20F WHICH IS RATED AT 16HP. It pushes my 4.5 ton at 6.5 k no problem in flat water. Not so good in much of a sea though. But for your displacement, more than adequate Iwould be concerned that the engine is underworked in your case, which can lead to other problems.Fresh water cooled and generally a great piece of kit if well maintained......Good luck.

 

[branko]

On my old boat( 31 ft) I have 2GM 20 motor. Motor was very good and only when I drive it in wind I have loose speed from approx. 6,5 to 4 KN.

 

[dulcibella]

I put a 2GM20 in my old Halmatic 30 (30ft and 5 tons displacement) and found I had loads of power. If you want a Yanmar engine (and my experience with them is excellent) a 1GM10 would provide plenty of power for your boat.