Black dust

[John Langford]

Over the last month, while cruising, my starboard aft engine mount has created little piles of black dust at the back end of the mount on the engine bed. The dust seems to come from under the mount. As the dust increases it falls aft off the back of the engine bed and settles on the floor at the back of the stringer. This is caused by engine vibration I presume. If I clean up the dust a new pile is created after a few days.

The mount seems fine otherwise. The rubber or neoprene seems ok (not sticky or degraded in any obvious way) and the engine runs and sounds the same (very smooth) with no alteration in vibration that I can discern. The bolts holding the engine to the mount and the mount to the bed are all tight and nothing has moved. There is nothing similar happening at any of the other mounts.

Has anyone else experienced something like this? The mounts are original equipment which makes them more than 9 years old.

[Ken Juul]

From your post it seems that your are focusing on the motor mount. Have you checked the motor mount with a heavy load on the engine?  At rest all may look good, under power the mount bolts will be under tension trying to pull out of the mount.  Any cracks or deterioration should be much more evident.  Another source may be the water lines to the heat exchanger that run down the stbd side of the engine.  Have you inspected them to ensure they are not chafing causing your dust? 

[John Langford]

Thanks Ken. I appreciate the quick reply.

I have checked all the lines (fuel, water and electrical) in the neighbourhood and they are all secured and without chafe. There is no question that the black dust is coming out of the mount. My sump and engine bed area is very tidy so it easy to observe any new detritus falling off the engine.

I have the rear engine box off so I will run the engine under load today and see if I notice anything going on at that mount. There is no question that there is something happening. I am just not clear if it is a major problem demanding that the mount be changed immediately or just something to watch (as the docs are so fond of saying to middle aged men...).

[sedelange]

Just curious, is the dust a powder like aluminum powder or is the texture more gritty like ground rubber?  If powder, check where the mount is attached to the engine, i think the mount flanges are aluminum.  If gritty, check to see if the rubber has delaminated from the metal part of the mount.

[Stu Jackson]

Just a long reach here, John, based on Steve's idea, but have you checked the secondary fuel filter bracket, per the Universal Bulletins?  See: http://c34.org/bbs/index.php/topic,3309.0.html  I recommend that you click on the embedded links within those topics to see more discussion about the issue.

[John Langford]

Thanks for further replies.

Stu, I have replaced the secondary fuel filter bracket. It is definitely not the source of the dust.

The dust is black and feels more like very finely ground up rubber. I might be able to sort out if the rubber is delaminating from the aluminum flanges by running the engine under load as Ken suggested. i will report back.

[sedelange]

John,

You might have to loosen the nuts holding the mount to the engine to see if the mount has delaminated.  If you do, just count the number of revolutions so you can get back the original setting.  Since you are getting dust, the amount of movement may be real hard to detect visually without disassembly.

[Ron Hill]

John : You can watch it "till the cows come home"!  What I'd do is buy a new pair of engine mounts and replace the rears. 
All you need to do is measure the hight of the rear brackets from the bed, disconnet the drive shaft, exhaust connection and loosen the top fwd engine mount nuts .  Then lift the engine (rear) up, move the old mounts out and the new mounts in (set to the height measurements of the old mounts).  Re connect and recheck the engine alignment and you should be good to go.  A thought

[John Langford]

Thanks Ron and Steve for further thoughts.

I ran the engine under load at the dock at a variety of rpms up to 2000 and observed nothing of any significance while doing so. There are no obvious cracks in the mount and the vibration of the engine seems smooth and pretty subdued. But I suspect that there has to be some kind of delamination allowing the flange to rub against the rubber and produce black dust.

I think Ron's advice is very prudent. I have read all the posts about the various Vetus mounts etc but much of it was directed towards replacing mounts for the M25 series. Does anyone know what mounts are actually installed for the M35Bs in the Mk IIs? They have a number on the flange (40510) but no manufacturers name. The lag bolts are 5" apart.They would appear to be a Westerbeke item   I can see them on p. 5 of the Westerbeke installation manual (http://www.westerbeke.com/InstallationManuals/installation_manual.pdf) but can't find any reference to them in any parts list so far. I may e-mail Joe at Westerbeke to see if he can help.

Any further thoughts welcome.

[John Langford]

Joe Joyce at Westerbeke says the original mounts are still available (Westerbeke part #040510) at $182 each. Yikes! I recall that the Vetus mounts (K-75) are around $65 each. Does anyone know the lag bolt configuration for the Vetus? It looks like it is closer to 4" than the existing 5" (centre-to-centre) for the mounts supplied with the M35B. Did the debate about whether the Vetus mounts required a flex coupling ever get settled?

Alternatively, has anyone located a cheaper substitute mount with the 5" centre-to-centre configuration?

[Ron Hill]

John : I believe that the Vetus K75 mounts have mounting holes 3" apart. 
Just look around for an engine mount (even call Vetus) in Defender/West for amount the 5" mounting holes. 
Just watch the minimum height that the mount will go down to - so you can get it under the mounting bracket !!!   

[Roc]

As John said, there are many posts about the Vetus mounts on the M25 engine.  Just curious, but has anyone replaced the mounts on a M35B engine with aftermarket mounts (Vetus or other)? 

Thanks

[Paulus]

Check out www.go2marine.com

[John Langford]

Here is information that won't make Canadian Mk II owners very happy. Westerbeke Canada wants $297.29 for each engine mount for the M35B. And I was trying to get used to the American price of $182!

It's a lovely engine but being at the mercy of Westerbeke is painful. There has got to be another mount out there that we can substitute. I went to the site recommended by Roc and it does have a lot of mounts. But sorting out which mount would be a good substitute is a problem.

Ron, did you have a view on the question of whether the Vetus K75 requires that then engine have a flex coupling?

[Roc]

John,
Check this site, Marine Parts Source. 
http://www.marinepartssource.com/details.asp?pnumber=JHW40510