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Kiltmadoc 08-20-2012 07:00 AM

Yanmar 2GMF problems
 
First admission: other than changing oil, we have not been too good with our diesel. The boat has also not had much use this summer (about 5x total).

The hull is scummy, but not encrusted, so we know that the hull is not the whole problem. A few barnacles on the shaft, but nothing more than usual for this time of year.

The problem: About 2 weeks ago, my boat partner went for a little motor cruise and the boat would not go past about 3 knots (normal for us at 2500 RPM is about 4-5 knots).

Yesterday, I got on board and the boat would not accelerate nearly as fast as before. The engine would not go past 2800 RPM (3300 is usual for our engine, 3400 is the max rating). The max speed was about 3.5 knots after a friend, who is a mechanic, bled the injectors and told us to get a new air filter.

He also told us to get a new fuel filter (and a "better" one than we have..racor R12P is the name on the filter).

The "charge" light goes on when the engine is on, complete with it's associated buzzer noise. However, the light extinguishes if the RPM goes up. We can get the alarm to turn off if we change the switch to "illumination" from the default "on" position.

Finally: the propeller shaft now has a distinct vibration to it and the negine seems to bounce around more than it did when we bought the boat 2 years ago. The engine mounts look ok to my amateur eyes. However, we do have powdery rubber-smelling material in the bilge.

The questions:
1. Bad alternator?
2. New filters etc would be helpful?
3. New engine mounts needed?
4. Anything else that we might be missing before I can a mechanic?

jameswilson29 08-20-2012 08:02 AM

Re: Yanmar 2GMF problems
 
How is the performance of the engine when in neutral? Does it rev freely? (Is this an engine or a drivetrain problem?)

Have you checked the throttle wire to make sure there is no catch?

Have you checked the idle adjustment/throttle limiting adjustment?

Have you checked the alternator belt? Can you rotate the belt with the engine off? Will it rotate when you remove the alternator? (If it is a bad alternator, I suspect you could replace it yourself).

Is the stuffing box/shaft seal/stern tube o.k?

How do you know about the barnacles on the propeller shaft? Did you haul the boat out?

arf145 08-20-2012 01:31 PM

Re: Yanmar 2GMF problems
 
I'd take JW's advice and look at in-gear vs. neutral for engine speed and vibration.

Quote:

Originally Posted by Kiltmadoc (Post 911841)
The hull is scummy, but not encrusted, so we know that the hull is not the whole problem. A few barnacles on the shaft, but nothing more than usual for this time of year.

If you've looked at the shaft, did you look at the prop? A few barnacles there can make a big difference.

Quote:

Originally Posted by Kiltmadoc (Post 911841)
He also told us to get a new fuel filter (and a "better" one than we have..racor R12P is the name on the filter).

Not sure what your friend meant by better--Racors are good quality. If they meant finer, unless your 2GMF doesn't have its own secondary filter, I think your 30-micron 12P is fine enough. But how old is the filter?

Quote:

Originally Posted by Kiltmadoc (Post 911841)
The questions:
1. Bad alternator?
2. New filters etc would be helpful?
3. New engine mounts needed?
4. Anything else that we might be missing before I can a mechanic?

I'm not sure where you're getting the bad alternator or engine mounts questions from. You've got a mixed bag of questions/issues there. Maybe the RPM/power problem has made you look at your engine overall, which is not a bad thing. But to stick to what you stated as "the problem" if the engine revs freely when not in gear, I'd be thinking fouled prop and then fuel. If you don't know when the Racor was changed last, change it. But I'd stick with the 12P unless your engine doesn't have a secondary filter. If you do have a secondary and you don't know when it was last changed, change it, too.

HPLou 08-20-2012 08:12 PM

Re: Yanmar 2GMF problems
 
Really sounds like a barnacle fouled prop. That is the first thing to check.

Kiltmadoc 08-21-2012 06:59 AM

Re: Yanmar 2GMF problems
 
to clarify: we actually dove under the boat. No fouled prop, no fouled propshaft, only light growth on the hull.
As far as does it rev up when in neutral goes: I'll have to check that. Thank you.

HPLou 08-21-2012 07:52 AM

Re: Yanmar 2GMF problems
 
A clogged exhaust mixing elbow would would also hinder acceleration. Other things to consider would be a clogged filter, water in the fuel and/or a worn fuel pump plunger.
Good luck and hope it's nothing serious.

aa3jy 08-22-2012 02:46 AM

Re: Yanmar 2GMF problems
 
Basic problem is the lack of use..change all the filters and tighten all the belts. Fuel may need to be polished or replaced with fresh. Check and clean water intake screen. Check and clean silencer(air filter). Check transmission oil level. Depending on age of the mixing elbow..it maybe in need of servicing. Again these are basic issues that can be done your self. Also there was no mention of any colored smoke on start up or under load which can lead to problem solving of various issues.. The service manual for that particular Yanmar is your friend..


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