Motor mount question....

[Greg]

Last weekend my engine started kinda "rapping" (not the music kind thank god) more of a vibration thing that would lessen at higher rpm's, after getting to port i checked out the mounts and one of the bolts was a little loose, I went through and tightened the hell out of all of 'em, the rapping is still there especially around 700 rpms. The mounts are just blocks of wood, should there be some rubber in there somewhere? It looks like there coulda been a thin strip under the blocks but it could just be some sort of silicone or adhesive. Part two...if I get some 1/4 inch flat rubber and put it in between the engine mount and the block of wood, would that 1/4 inch mess up my alignment too much? or does someone have a better solution.thanks,Greg

 

[David]

Mounts

Part 2: Yes it will change your alignment.

 

[Don Bodemann]

need new mounts

Greg,It sounds like you need new mounts. Hang on to your wallet cause Yanmar mounts aint cheep. Replacing the mounts is a little more of a job than meets the eye. As you have suspected, alignment is critical and with new mounts, a realignment is a must. I would recommend getting all new mounts, lube them up good, and then align the flanges...with the bolts out of course.

 

[steven f.]

in addition to mounts

I had a similar problem last year and after having my mounts replace (along with a new PSS and x-mission coupler installed) the problem persisted! It didn't matter if the shaft was turning or not, it was dependant on the engine RPM's. After much thought I finally discovered that it was the shaft vibrating against the shaft log in the stern tube. Long story short, the engine was WAY off of alignment. I had a local guy come in and in 2.5 hour$ of his time I had the problem mostly solved (still very minor vibrations from 1250-1350 RPM.) Looking back at it now I probably didn't even need the new mounts, oh well, they were the original mounts that were fifteen years old anyway....

 

[Sam Lust]

More than meets the eye.

Before the engine is aligned to the shaft coupling the shaft MUST be aligned to the shaft log. (The elongated hole hole in the hull through which the shaft passes.) Once the supporting strut, shaft and log are in perfict alignment THEN the engine coupling half gets mated to and aligned with the shaft coupling half. You'll probably always fet a little bit of rapping at some point or another. Mine does it under sharp deceleration. What do you do about it when it's minimized to that point? To quote my wife: "Turn up the radio."