Engine Mounts

[Bill19233]

Okay, while they put on new bottom paint, I had the yard install a new prop seal and I went ahead and had them replace the cutlass bearing while the shaft was out. They also checked the shaft, said it was good. He recommended new engine mounts, one looks pretty bad from a mixing elbow leak I fixed last year. The others look fine, but the rubber breaks down, I'm told. The boat is almost 15 years old and about 700 hrs. on the engine.

So, as soon as I replenish my disposable income that goes into the boat after this yard bill, I think I'm going to buy new mounts to install myself. He recommended the R & D Marine mounts from PYI over the stock Yanmar mounts.

Anyone use the R & D mounts and have good luck? Or, should I stick with Yanmar parts, the price looks about the same. Anyone by chance buy R & D's for a 3GM30F and know the part number?

Or, don't worry about the mounts at all until the rubber starts to fall apart?

Thanks

 

[kloudie1]

They will get pretty bad looking (rusty) but the way to check them is to look at the clearance between the top steel and the bottom steel. I forget the number, I think somewhere around 1/4"or 1/2" loaded for a minimum.. Search the site using Yanmar Engine Mounts and you'll see a lot of discussion.. I replaced mine last year on my '85 model and they still had life in 'em.. Good luck, Bill.

 

[Benny17441]

Worthwhile investment, they will tame excessive engine vibrations which in turn will extend the life of the running gear.

 

[Steve Dion]

Bill: There is a lot of information regarding Yanmar motor mounts. The ones for the GM engines have different fore/aft mounts. I do not think that the aftermarket are made this way (you need to research). Considering the OEM ones have lasted for 30 years I would think you would just go with the Yanmar ones.

We had a fellow in our marina have a new engine (Yanmar) installed in his H'30 late 70's model and the engine almost shook itself out of the boat because the installer used the OEM mounts in the wrong positions.

 

[Ken13559]

If I have to change mine, I'll go with OEM. At least the holes match, no need making more holes.

 

[kloudie1]

More info: First determine if you need new mounts.. then if you do, probably best to go with Yanmar parts: http://www.yanmarhelp.com/i_mounts.htm
There is a lot of good info on that web site.. I thought this was where the min clearance spec was for the mounts, but I can't find it.

EDIT: this thread has some info ;
http://forums.hunter.sailboatowners.com/showthread.php?p=962604&highlight=Yanmar mount

 

[robertsapp]

Yanmar says the mounts are good for ten years. We all know they last longer, but it wouldn't hurt to replace yours if you want. Stick with original Yanmar parts. You'll use two 100lb mounts under the front of the engine, and two 75lb under the rear. The job is easy if you already have your engine enclosure pulled apart for some other reason, you just use a 4x4 across the companionway with a 1 ton chainfall (very cheap at Harbor Freight) to lift the engine and swap out the mounts. If you don't have the engine box opened up, you'll have to use a jack from underneath. Be careful to use something to distribute the weight of the engine on the jack so that you don't punch a hole in the oil pan. Use a sharpie to mark the outlines of the existing mounts on the beds so that you can install the new ones in about the same place. It will save you a bunch of time when you re-align the engine afterwards.

We were able to eliminate the annoying vibration we had on our boat when we replaced our motor mounts. We found out that either the factory or the previous owner had put the two 100lb mounts under the port side of the engine and the two 75lb mounts under the starboard side. No wonder it shook so much!

 

[Bill19233]

Thanks Robert, I knew I had seen something about ten year life on motor mounts. I am trying to eliminate vibration that probably wouldn't bother anyone else, way less than the three newer Sailtime boats I used to be on. I think I'll chase fuel problems (filters, air leaks, etc...) and tweek the alignment a little more before I spend the time and money on new motor mounts. But, the yard owner that just did my bottom job says most vibration problems are worn out motor mounts. If I do, though, I'll get Yanmar.

 

[robertsapp]

Thanks Robert, I knew I had seen something about ten year life on motor mounts. I am trying to eliminate vibration that probably wouldn't bother anyone else, way less than the three newer Sailtime boats I used to be on. I think I'll chase fuel problems (filters, air leaks, etc...) and tweek the alignment a little more before I spend the time and money on new motor mounts. But, the yard owner that just did my bottom job says most vibration problems are worn out motor mounts. If I do, though, I'll get Yanmar.

We needed new mounts, because one of ours was torn, but I think what was causing the worst of our vibration was the prop. I sent it to the local Accuprop to have it checked, and one blade was pitched almost a full inch more than the other. I honestly don't know if they come from the factory properly balanced, or if they assume that just like new tires, you'll have them balanced (pitched) before installing.

Oh, and another thing is that our shaft was too long. You shouldn't have more than one shaft diameter (1" in our case) between the forward face of the prop and the strut. I measured almost two inches from our prop to the strut, so I had the machine shop cut an inch off the shaft and face a new coupler. So once we'd gotten the prop properly pitched, fixed the too-long shaft (came from the factory that way), installed new mounts and Cutless bearing, and then did a proper alignment, all our vibration was gone.

Sometimes the problem is that something's worn out, but often times the problem is that it was done wrong at the factory and needs to be corrected by the owner.