Yanmar Engine Mount Worries

[jaysweet]

would love to see pictures of the engine hobby horsing. Did it make any unusual noise? As was said, check all mounting bolts.

For yanmar engine mounts….. great product, great price and fabulous customer service try these guys. In Europe however ships directly to you. The owner/engineer will call you directly if you have e questions.

Www.ellebogen.com

goodluck
Greg

My hands were pretty full with keeping the boat going and safe, so no video (although I wish now I had taken one). No noise. It was pretty freaky to see the engine moving like that when it was shut down, just from the prop auto-rotation, though!

I've seen the Ellebogen site a few times over the years while reading about... engine stuff, including yesterday and the day before. I can't prove it, but my impression of their product is quite favorable, so I think they'd be a very good alternative to genuine Yanmar mounts.

 

[jaysweet]

Look at the fasteners that hold the mounts onto the stringers. Some boats come with lag bolts and those can loosen up.

Right: I didn't take the time when I got back, but that's the first thing on my list.

 

[jaysweet]

The mounts can be checked by measuring the clearance between the top and bottom steel plates. I seem to remember that it should be no less than 3/8” but I don’t have that at hand right now. I agree with checking for prop fouling and definitely checking alignment.

Mine are certainly not knocking steel against steel. The other thing that could have happened is that I suppose the steel plate could detach from the rubber block. Or the rubber could crack. This seems like it might be easy to miss with a quick visual check? Mine looked fine to the eye.

 

[jaysweet]

For the YM series it’s the end of section 2.2 of the Service Manual, and it is exactly the intervals you said. I do wonder how many actually get replaced at 4 years.

I decided years ago with cars that the main thing was to replace the engine oil and filter religiously, and take care of the tires. My theory has been that if you paid to have all the other suggested maintenance done, you'd be out WAY more money than just waiting until something broke before fixing it. (I've done 90% of the work myself since the 1970's, but time spent is still time spent.) To that short list (oil, filter, tires), I've recently added replacing the brake fluid periodically, as well as anti-freeze. I recently had my 2004 Toyota Tundra brakes stop working b/c of corrosion inside the front brake cylinders due to water absorbed into the brake fluid, so that's something I've learned from keeping a vehicle for 18 years. The brakes still worked, but less well than they should have (it was mainly the rear brakes that were stopping me).

Anyway, the marine environment is quite a bit more harsh than most cars see, so the Yanmar has gotten better treatment, but frankly oil and filters (oil/diesel) and belts has been the majority of it. I'm embarrassed to say that I just did the anti-freeze for the first time this summer on a 2004 boat. My hot water heater is still original, so I guess rusting out b/c of the antifreeze hasn't been a thing. The Yanmar has been dead reliable for all 18 years until I had a fuel leak in the primary a few months ago.

 

[jaysweet]

I replaced my mounts at about 27 years.. One was collapsed, the other three were still fine. The collapsed one had about 3/16" between the steel plates which would touch under some conditions of power and heel. That mount sounded like someone was under the boat with a hammer when it happened.

Mine all looked fine with a cursory inspection, but I'll look closer when I go out next. I just wish this had happened in early June, so it didn't impinge on my mid-Fall cruise plans.

 

[Benny17441]

Don't go by looks, in these motor mounts, looks are very deceiving. You can get a pry bar and start lifting the engine at spots and stretching the individual mounts. A broken one will show right away and a weak will allow to lift the engine with very little resistance.

 

[jaysweet]

Here is an interesting article about engine mounts in the magazine Ocean Navigator.

Replacing engine mounts - Ocean Navigator

If your engine mounts are more than five or six years old, or have been contaminated with seawater, engine oil or coolant, change them. Even if the mounts look perfect, the tough elastomer (rubber-like) material in the engine mount work-hardens over time and ceases to isolate the boat from the...

oceannavigator.com

​

"Yanmar mounts are manufactured specifically for each side of the engine. That is, either the starter side or the oil filter side, as engine torque will change the effective loading on either side of the engine. Make sure that you get the mounts positioned on the correct side of the engine."​

​

Thanks for that, John, and good luck with your rebuild. I'd certainly replace the mounts if I were rebuilding the engine.

I got back to the boat yesterday, and yes: the Yanmar mounts are size 75 on the starboard side and 100 on the port side. Don't know how I would have figured that out without an iPhone camera. Here are the mounts, port aft, port fwd, stbd. fwd, stbd. aft:


It's certainly hard to tell from the picture, but they looked fine to the eye. I'm pretty sure the black flakes are just from the fact that someone seems to have spray-painted the mounts black (including the rubber), and it's flaking off. You can see the black paint on some of the nuts. The starboard fwd. mount has a bit of rust, which I think came from a leak in the saltwater cooling above it somewhere, but it's not all that extensive.

So I ran the engine at the usual "low-vibration" idle speed (1200) in neutral. Looked pretty normal. Put it in forward at 1200 in the slip: the vibration seemed significant, but I'm really not sure I've ever observed it at this RPM in gear before (port side, forward):

I took a video of the other side and of the top, but they seem to be too large to upload. But they're similar.

So at 1200 in forward, there was significant vibration on the forward side of the engine, although perhaps not as much as I had remembered. In reverse at 1200, no vibration to speak of. Took the boat out, and again the engine looked smooth at 2800 to 3200 RPM, which is my normal cruising range. So I think my conclusion is that I've just really never looked at it closely enough at 1200 RPM except when the engine is in neutral at the dock (when the vibration is pretty minimal). So the vibration I noticed on the trip was at 1200 in neutral with the prop freewheeling b/c of forward motion from sailing and with the engine off with the prop freewheeling b/c of forward motion from sailing. I had no vibration in reverse, or at normal cruising RPMs. I think I'll keep a watch on it, maybe align the engine (for the first time) at the end of the season, and aim to replace the engine mounts some time in the next year or two. (Assuming I have no further problems.)

 

[jaysweet]

Mine are about 20 years old and have 900+ hours on them. Engine is solid and doesn't vibrate. I'm not in a hurry to replace them.

I think I'm with you on this.

 

[jaysweet]

If you are thinking about buying four new mounts, I have four that I bought from a British company a couple of years ago and never used them. They are not in a Yanmar package but appear to be the same as oem. Two are 75 series and two are 100 series for front and back. $200 for the four.

Thanks for that. I think I'll hold off and look at the Ellebogan site when it's time.

 

[RoyS]

Hard to tell from the video, but there could be a separation of the engine mount top plate from the rubber blocks inside the mount. I would put a pry bar down there and raise the engine while looking for such a separation. If you watch the video closely the top plate seems to move independently of the rubber blocks at times.

 

[kloudie1]

Quick note: The parts book shows the two front mounts to be "100" and the two aft mounts to be "75" . The 100's to support the weight of the engine block and the lesser rated ones to support the lighter transmission.

 

[jaysweet]

Hard to tell from the video, but there could be a separation of the engine mount top plate from the rubber blocks inside the mount. I would put a pry bar down there and raise the engine while looking for such a separation. If you watch the video closely the top plate seems to move independently of the rubber blocks at times.

It could be, but I couldn't see it. The pry bar idea is a reasonable one, which I think I'll try.

 

[jaysweet]

Quick note: The parts book shows the two front mounts to be "100" and the two aft mounts to be "75" . The 100's to support the weight of the engine block and the lesser rated ones to support the lighter transmission.

I believe you, but I've also read elsewhere that the different sizes go on different sides of the engine, which is how mine were installed by Hunter. Sounds like a topic for another couple of pages of debate!

 

[senang]

Here is the page of our 3JH4E manual for the engine mounts. It shows a port/starbord differentiazation in hardness for the mounts.

 

[mermike]

The OP has a 2GM. Unlike the 3JHE series, the 2GM mounts are differentiated fore and aft, 100 and 75 hardness respectively. Check the parts manual.

https://sbo.sailboatowners.com/downloads/Hunter_gen_35455487.pdf

 

[dLj]

Just sayin', every 4 years to change engine mounts seems mighty frequent to me. I'd be looking to have a way to measure that need...

dj

 

[Tally Ho]

Just sayin', every 4 years to change engine mounts seems mighty frequent to me. I'd be looking to have a way to measure that need...

dj

Mine are probably original (1988). I guess I better start thinking about doing something with mine…

But I have only owned the boat for 8 years.

Does the fact that my boat is on the hard 6 months of the year meanI get 8 years?

How about the fact that I generally motor 30 (15 minutes out and 15 minutes back in) buy me more time?

Greg

 

[dLj]

@Tally Ho - I would certainly want a way to measure the need to change a mount. Looking back at all the vehicles I've owned throughout the years and the number of times I've had to change motor mounts, 4 years seems extreme overkill.

I'm thinking about an FJ40 I used to own. Used to do pretty extreme four wheeling in that beast. I had to change motor mounts at about 8 years in that vehicle but I'd have to say my use of that one would have been similar to sailing the Southern Ocean for several years in a sailboat.

I'd gone down a ravine that took out a front wheel; had hit a bridge abutment and plunged down into a river head first; was driving across a field with grass up to the hood and hit a tree stump that you couldn't see that nailed me right in the front drive pumpkin. Man that one was the most abrupt stop I ever experienced. Now that event might have been the straw that broke one of the motor mounts. It was after that event I rebuild the beast and kept on four wheeling.

I find it hard to imagine sailing is more extreme than that but I guess if one is sailing in rough seas a lot, you might want to have a way to check your motor mounts. But just because the mounts have been there for four years doesn't seem to me you need to change them. But the question in my mind is how do you check them? Sure, you can tell when they are broken. But how do you know if they are close to breaking?

dj

 

[jaysweet]

As far as fore/aft vs. port/starboard differentiation in motor mounts: all I can say is that Hunter did mine with the 100's on the port side and the 75's on starboard. Since I've never really had a problem (the recent "problem" is looking more and more like it's either me just noticing something I never noticed before, and/or perhaps I should try to realign the motor), if and when I do replace them, I'd stick with the way they were installed by Hunter.

BTW: I went out there today and used a pry bar to pry up on the top plate of each mount while down there with a flashlight and my eyes close to the mounts. (I have very good access to both sides.) All 4 mounts look fine to me. The only things that could be wrong were not: the rubber flexed properly and it was not pulling away from the metal bracket on either top or bottom. The studs are not loose, nor is the mount loose on the support stringers.

So that really only leaves alignment, which I will check when I have more time. For now, I'm getting next to no vibration when the engine is:
1) idling at 1200 RPM with transmission in neutral, and
2) running full out at either 2800 or 3200 RPM with transmission in forward.

I am still seeing some vibration when
3) idling at 1200 with transmission in forward, and
4) engine off, and prop freewheeling.
I'm really not sure I've ever checked it carefully in those last 2 situations, as I'm usually busy with other things at those times. #4 sure does seem odd to me, though: that the engine could be vibrating just from a freewheeling prop.

By the way, I've read in quite a few places that I should let it freewheel when sailing, which agrees with my gut feeling. It just feels like it puts a heck of a lot of stress on the shifter to put it in reverse and take it out again with the engine off. Feels wrong.

 

[mermike]

I'm a follow the manual kind of guy. I never, ever assume that the "highly trained technicians" at the factory knew what they were doing when they did what they did.