engine mounts MDIIC

[petersto]

The info. I recieved last time from this site was so good I thought I'd push my luck!!! I have a MDIIC how long would you expect the engine mounts to last. Is there a way of assessing their condition both physically and visually. The reason is that I have a fair amount of vibration when motoring and thinking of the possibility of eliminating the cause the engine mounts seemed to be first in line. The engine itself sounds sweet. Also the stern gland and shaft shows no signs of sideways movement. In anticipation, thanks.

<hr width=100% size=1>

 

[mdrifter]

Take care to shop around for replacements since you may find that you could buy a set of 4 for the cost of 1 "Volvo"!

<hr width=100% size=1>

 

[dickh]

The place to get mounts is <A target="_blank" HREF=http://www.trelleborg.com>http://www.trelleborg.com</A> They supplied most of the mounts for the majority of marine engines, either under their own name or 'Metalastic' who they took over some years ago - but the matalastic range still available. Look for any part no's on the mounts(you may have to wirebrush them if they are rusty).

<hr width=100% size=1>dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[dickh]

The place to get mounts is <A target="_blank" HREF=http://www.trelleborg.com>http://www.trelleborg.com</A> They supplied most of the mounts for the majority of marine engines, either under their own name or 'Metalastic' who they took over some years ago - but the matalastic range still available. Look for any part no's on the mounts(you may have to wirebrush them if they are rusty).

<hr width=100% size=1>dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[maxxi]

Hello again,

Firstly, don't assume that the mounts that you have under your MDIIC are standard, or even matched to the engine. Many marine engineers and boatbuilders, particularly those whose name might suggest that they are not from the easterly end of our island, tended to fit whatever they had in stock at the time, regardless of specification. So, check the origin and model number and check with the manufacturer's data to ensure that what you have is within specification.
I had a Gosport based engineer, a long time ago, fit mounts to my 10hp engine that were specified for 260hp upwards. The end of another lovely relationship.

Alignment of the shaft to the gearbox coupling is next, and this is a feeler guage job, and not divinable by eye alone.

Straightness of the shaft - any slight bend will give you vibration, as will any imbalance of the propeller.

On your engine, at tickover, try operating one de-compression lever and note the rpm that results, then try the same with the other cylinder. Disparate power output between the two cylinders just could be one of your problems, or the problem.

The mounts should last very many years, any problems usually being the outcome of abuse, particularly contamination with oil, fuel or otherwise.
Put a good prybar under an engine foot and lift, if the top section of the mount comes away from the lower section, the mount is totally u.s. Repeat for each mount. If any one mount is no-good, it would be beneficial to fit a complete new set and not just the one.

Also check with the engine stopped, that there is no lateral, longditudinal or torsional deflection in the mounts.

Sounds as though you are in for a busy lay-up.


<hr width=100% size=1>

 

[Avocet]

Be careful operating the decompressor while the engine is running unless you KNOW the valve won't hit the piston! Also, I got a set of 4 (have nearly finished paying off the second mortgage!) Vetus hydraulic engine mounts for our little single cylinder engine and was very impressed BUT the mountings reduced the vibration by allowing the engine to move more - this transferred the problem to the rigid prop shaft coupling so I had to make a flexible one.

<hr width=100% size=1>

 

[petersto]

Thankyou all for taking the time. I think I will have a good look at the engine mounts first as suggested by Maxxi. I had already thought about shaft/gearbox alignment and was advised to do this when back in the water. I shall also look at the recommended website and review the costs involved. Before my present boat I had a Vivacity 20 it virtually looked after itself. Makes you wonder sometimes.

<hr width=100% size=1>

 

[PaulAG]

Sorry about delayed response - only just seen your query. I have just fitted 4 engine mounts to MD11C on Centaur, as original ones (30yrs old) were soft with diesel spills etc. When removed, only on one were the top and bottom metal plates still solid with the rubber!! Great difficulty in undoing nuts and bolts! Lifting rear of engine OK as it is quite light, but different matter at flywheel end and very awkward to get a jack underneath. Chock up safely with wood to work underneath. Surpisingly when new mounts in position and checking the alignment, this was within 1 thou'. There is no indication in the workshop manual nor owners' manual as to how to align, but if needed would probably be shims under the top of the mounts - no room for second adjusting nut. As the stuffing gland is on rubber tube and there is nearly 1/4" space available, slight mis-alignment probably permissible. I still have some vibration, but traced, as previous poster said, to different power outputs from the two cylinders. Injectors servicing next job.

<hr width=100% size=1>PaulAG

 

[Lofty]

I have an MD11. I recently had a vibration problem and finally traced it to the coupling between gearbox and propshaft. My coupling consists of four rubber bungees mounted between two plates. One of them was torn and replacing it sorted the problem. It is worth checking if any one of them has failed this will cause a lot of vibration.
I lift my engine not from underneath but by placing a heavy plank across the cockpit. I put a Bedford screw jack on top of this and then tie a circle of rope round the jack under the plank and through the lifting eye on top of the engine. Screwing the jack up lifts the engine. No rouble at all.
Hope this helps. And good luck.

<hr width=100% size=1>