Yanmar diesel sometimes shakes, sometimes doesn't

[palmettobum]

I'm a little worried about my engine:

It starts up fine and runs great. I throw out the anchor and have a nice lunch. After lunch, I crank the engine and the idle is fine, but when I start to turn up the RPM's, it will shake. The more RPM's I give it, the harder it vibrates.

I turn the engine off for a second. Restart it, and it runs normally.

I haven't had the engine realigned since I purchased her (3 months ago), so I'm thinking it could be an alignment issue. Any other suggestions?

Thanks!

 

[kloudie1]

Make sure the injectors are bled .. then have the motor mounts checked.. Then alignment. should smooth her out.. (you do have the Yanmar 3 GMF, and not the Westerbeke?)

 

[Sanfelice]

Yanmar mounts

I'm afraid you are suffering from worn out engine mounts. Yanmar mounts are designed to keep vibrations to a minimum and will wear out more quickly. Earlier models were worse than the later ones. The symptoms are that at idle, and very slow speeds, the engine is smoothe running. Giving it some quick throttle, and the engine will vibrate significantly. You might be able to get the revs to get in concert wth the engine vibration if you slowly bring the revs up. Next time you are on your boat, open the engine compartment. If the engine is rocking back and forth when the engine is reved,you most likely need new mounts. You will see what I mean. The engine vibrations will continue to get worse as time goes by. The Yanmar mounts are not cheap but if you want less vibration I would replace them with OEM. Good luck in fixing your problem.

 

[Joe Mullee]

Is Replacing The Engine Mounts A DIY Type Job?

I have similiar problems with the engine on my H34. I have the Yanmar 3GMF. At idle and up to 1400 RPM's I never have any shakes. But as I slowly increase the RPM's it sometimes gets the shakes. What I do is give it a quick burst of throttle and it pushes right thru and immediately settles down. At that point I can go up or down on the throttle without further problems.

I've looked over the rubber mounts and they look like they could use to be replaced. Is that something I coulld do myself or is it something that's best left to a Yanmar engine specialist?

Thanks,
Joe Mullee

 

[heart of gold]

If you have the original 2 blade prop, its going to add to the vibration as well

 

[Dan Johnson]

Joe & Palm...

Joe, you can do it yourself if you are meticulous in taking measurments before, during and after to get the alignment correct. Just remember that the front mounts are different from the rear mounts when you go to purchase the replacements. In this case, anecdotal evidence favors Yanmar's mounts over alternatives.

Palm: check to see if you're not leaking some diesel around the Yanmar filter or its bleed screws (a common problem). Shakes are sometimes due to air getting into the fuel line and then roughness occurs until it works its way out or is bled out.

 

[palmettobum]

The engine is a Yanmar 3 GMF. The prop has 3 blades.

Thanks for the info. I'll take a deeper look around the engine next time I start her up. Checking for the engine rocking during high rpms (mounts) or diesel leaks allowing air into the fuel line.

I'll give it a look.

 

[Sanfelice]

Engine

Here is pretty good article on mounts and alignment. Yes, you can replace them yourself. Take careful measurements from existing mounts. The engine can be jacked up enough from underneath using a small jack. Be careful not to crush the oil pan. Even better. if you can access the engine fro above lift it up about 4 inches. You will need to undo the flange bolts.

http://www.yachtsurvey.com/alignment.htm

Another site that may be of help.

http://www.pbase.com/mainecruising/motor_mounts