3QM30F with JH mounts?

[sail_4_me]

I'm looking into replacing the mounts on my 3QM30F ( 1983 37 cutter ) because I'm getting a lot of noise and vibrations at different RPMs, and I think I may also have issues with the prop, which is a maxi 2 blade folding design.

At 2500 RPM there is a lot of vibration and 'knocking' or 'clacking' that seems to come and go with the waves, ie. as the boat moves down/up, there seems to be an increase in vibration and noise. I've checked the rudder/post and all the bracing down the rudder, its totally solid and strong. I also looked into maintenance on the maxi prop before launch, and it has no adjustments needed or greasing, and it was on soliid.

At 1800 RPM, I do 6 knots, it seems to be the engines sweet spot, but there is still vibration, although not nearly as much as at higher RPMs.

At 700 RPM there is a pronounced banging/knocking sound that comes from somewhere. This also occurs when the rpm is very low. It sounds like the side of the engine is banging against the wood, but I've looked around and not seen that, no clues yet.

Here's the fun part. I asked my local shop for quotes on new mounts, and gave them pictures of the ones I have. They responded that I seem to have the wrong mounts, that I may have JH mounts on my engine!

Do any of you with 3QM30 engines have engine mount pictures, or similar stories? See attached picture of my front mount. I expect you will also think the mounts need changing, but I'm nervous about changing to a 'round' mount as was supposed to be there originally, or replacing with the same ones. I also just noticed how close to metal parts are in this mount. Perhaps thats where the banging comes from....?

 

[Steve Dion]

I would suggest that you ONLY use the OEM mounts that are designed for your engine. I do not have any idea with the QM engines. The GM engines have different mounts fore/aft. The JH engines use different mounts port/starboard.

We had a H'30 that was refitted with a 2GM, the folks that installed the engine did not realize that there were different mounts for this engine and they reversed them. The boat also shook itself to death. It was moving so violently, the shaft actually seperated from the coupling.

Need I say more. Get QM mounts.

 

[rardiH36]

Here's a link to a thread from a few months ago which although not specific to a 3QM, might have some interest http://forums.hunter.sailboatowners.com/showthread.php?t=120151:

- It has a partial pic of the engine mount on my 2QM20
- The first response by SanFelice has a link to a site that shows a picture of "round motor mounts.

 

[Jim Legere]

Engine Mounts not rocket science

I have replaced the mounts on my 1983 3QM30. About six years ago I broke an engine mount (sheared the stud) crossing the Gulf of Maine in some of the famous "Fundy Square Waves" - a wind against tide situation. Athough the engine shifted slightly, I was able to get home, motoring the last 50 miles in fog, thunder and lightening. I had to replace the propellor shaft as well as the mounts. I used R&D mounts - I don't remember the model but they were selected based on the weight of the engine and transmission. I have heard that Yanmar used different mounts on front and rear (presumably stiffer mounts aft) but I used the same mounts all round and have not noticed any difference in engine vibration. I always had a rough spot between 1800 & 2000 RPM and this did not change. Changing the mounts, shaft, cutlass bearing and realigning everything kept me busy and cursing for a couple of days but, six years later, I am still happy with the results.

 

[Ed Schenck]

3QM30 Engine Mounts

My original engine was a 2QM20. Here are three pictures of 1) the 'QM' original mounts, 2) the new 3YM30 mounts, and 3) a closeup of a 'YM' mount. Yours are definitely not original.

 

[Jim Legere]

Not so sure Ed...

The original mounts on my 3QM30 that I had to replace looked exactly like the ones in sail_4_me's picture - not like yours. Perhaps there were different mounts for the 2QM20 and the 3QM30 because of the difference in weight?

 

[coleman]

Just for reference, look at the engine lines and the mounts in particular (BIG FILES). I need to see if I can find a photo of my engine because I honestly cannot remember for certain which I have:

2QM20/3QM30:
http://www.yanmar.com.au/superseded/2QM20 3QM30/2QM20 3QM30.pdf

2QM20F/3QM30F
http://www.yanmar.com.au/superseded/2QM20F 3QM30F/2QM20F 3QM30F.pdf

 

[sail_4_me]

Thanks for the great info everyone. Jim, you also have a 1983 correct? I kinda feel that your right, and these are my original mounts, done by Hunter. If they were actually replacements, would they look as worn out or crappy? I'm also pretty sure the last owner didn't replace them.

I think my best approach may be to get the mount numbers, and a quote to replace them and align the engine after. If I get a good ID on the part numbers, then I may also be able to find out if they are actually rated for the engine weight and HP... I can also ask about ratings for the 'original' mounts.

If you were able to find which mounts you purchased from R&D that would be appreciated. The link to their site - http://www.flexible-coupling.com/r-and-d-engine-mounts-dimensions.html

 

[Jim Legere]

Yes, I believe the mounts that I replaced (that look the same as the one in your picture) were the original 1983 mounts. Give me a day or two and I will try to dig up the specs on the R&D mounts I used as replacements. I'll be in touch via email through this site.

 

[sandpiper10471]

I have suffered the same banging and rattling at low rpm as you. Turns out the shaft barely misses the shaft log where exiting the boat. At low rpm - vibration zone - the shaft hits it. On a calm day at dock, run the engine, get it rattling and see if you get vibration waves in the water surface. If not, that likely is not the problem.
I repowered and most of my problems have come from a strut that was twisted and bent - by the PO of course!

 

[Bill1565]

I am really exited about this thread!! My boat has a PO installed Westerbeke 35D. Had Horrible metallic banging at all rpm in and out of gear when I bought it( cheap). replaced old worn Martec folder with Campbell sailer 3 bl, went for new shaft. Re mounted strut, alligned everthing. Fixed 99% of the problem. Still have vibration at 2400 RPM. In gear and out. Been puzzling myself silly over it.

Had in mind calling all of my mechanical friends over for pizza and beer(6 pack and medium would serve them all).

Now first thing I'm going to do is walk to the boat and verify my recollecton that i have round mounts and fwd starbord one at least is bent. Would have been like PO to replace engine, keep motor mounts, especially if they were expensive.

 

[kloudie1]

Wow, Bill.. Ya have only a half of a mechanical friend?? or one that eats like a half!

 

[Bill1565]

Yeah, on a good day i have a half a friend.

 

[coleman]

Anyone use this specific model of R&D mount through PYI Inc.?

"PYI Inc., the U.S. Distributor for R&D Marine Ltd., offers a complete range of engine mounts for Yanmar installations. PYI Inc. has combined the proven engineered features of the R&D Marine flexible engine mounts with a simple reliable lifting block to duplicate the height and bolt spacing of the Yanmar mounts."

Link:
http://www.pyiinc.com/index.php?section=news&action=2009/5_20_09_yanmar_mounts&sn=8
PDF Brochure:
http://www.pyiinc.com/images/pdf/rd/RD MOUNTS FOR YANMAR.pdf

 

[kloudie1]

Bill, most motors have a resonant spot at some low RPM; (usually a good bit below 2400) soft mounts make it really visible. broken mounts make it bad. If it is not hitting the inside of the shaft log (as Sandpiper mentioned) it is probably not doing any damage.. but do get a mechanically inclined buddy to look at and listen to it .. Use a piece of 2X4 about 4-5 feet long to lever the engine up from underneath and watch the mounts to see if there is more looseness in one or two.. Listen in the flywheel area for the characteristic rattle of a cracked dampner plate too.. Good luck in your hunt..

 

[Jim Legere]

R&D Engine mounts

I used four of the 800-011 mounts (without the "Y" which I think the designates the 7/8" shim for Yanmar applications). They were a bit shorter than the original 3QM30 mounts, so I made my own shims out of 1/2" UHMD plastic. They have been in four years and seem to work fine.

 

[sail_4_me]

Jim and Coleman, thank you for the excellent information.

Jim, from the R&D PDF spec, it seems you picked a heavier than required mount for the 3QM30. I wonder if this changes the dampening quality of the mounts. I also noticed that the Yanmar part #'s are listed, sweet!

 

[coleman]

...Jim, from the R&D PDF spec, it seems you picked a heavier than required mount for the 3QM30. I wonder if this changes the dampening quality of the mounts...

Not necessarily, but it seems like a safe bet. The mounts from Yanmar are meant to match a range of engine thrust loads and weights, not really so much on the resonant frequency of the system (same, more obvious, with R&D). It's the case with the 3QM that the rear mounts are strong enough to handle the thrust alone and the front are just along for stabilization and keeping the transmission pointed in the same direction. Since the mounts are applied to multiple engines, it's likely not a fine-tuned package for any and you may be able to experiment?

If I had more money lying about I would get the Aquadrive or any of the other very nice CV axles available for the marine engine market. They also have engine mounts to match the kit which are much softer than factory because they no longer take propeller thrust loads. I have always thought that the act of carefully aligning a sailboat engine was sort of silly when one could just fix the problem altogether. Anyways, it's on the wish list of things likely not to ever happen unless I determine that a complicated $1300-$2500 system would give my much more expensive drivetrain several more years when not much else could...

 

[Jim Legere]

Shaft limitations on the H37C - Drivesaver?

One thing with the 37 cutter - there isn't much room behind the engine! I haven't measured it, but I would guestimate that there isn't much more than 12" from the back of the transmission flange to the front of the stuffing box. I reckon you might be able to slip one of those flexible coupling/dampers in there (eg: Globe Drivesaver http://www.globecomposite.com/pages/products_drivesaver or R&D makes them too) but even then you might have to shorten the shaft to avoid chewing the rudder I don't know how much they actually reduce noise and vibration - anyone have experience with the Drivesaver or similar?

 

[Bill1565]

PO added one on my boat. Shaft was long, but didn't impact rudder. This one is pale yellow about 1/2 " thick. It is cracked half way, and one of my thoughts was to remove it so I could align the flange halves more accurately. Never had one on any of my other boats, didn't miss it .

After following this thread and the others it leads to better alignment is not high on my list. I didn't know there were universal joints for prop shafts. Will look into it. Not that money is no object, but a haul out,pressure wash block,and launch comes near $500. I'm already in for one, only fixed part of the problem. Anybody out ther have experience ith them??