New Engine Mounts

[kloudie1]

Finally got time to replace the engine mounts on my Yanmar 3GMF. haven't run it yet but I suspect some of the banging was the saggy, old (kinda like the owner) engine mounts.. Interesting, two were pretty good and two were totaled.. Also noted that the new fronts, 100# rated, now have a larger diameter stud than the 75# rears . The new rears are same stud size.. No mods or drilling was necessary.. but the top nut on starboard front is mighty close to the throttle cable.

 

[Rocket1]

RE: 3GMF mounts

I too am needing to replace the mounts on my 3GMF. Where did you get yours from and how bad was the damage to your wallet? I've noted that Yanmar is mighty proud of their parts.

Thought about going aftermarket, but think I'll bite the bullet and go OEM with the mounts.

Was the task a challenge, or fairly straightforward?

 

[kloudie1]

The mounts were expensive .. almost $400 .. I got them from my excellent, friendly local Yanmar distributor, Laborde Power (http://labordeproducts.com/default.asp?page=dealers) Yanmar is very protective of their parts business so you'll have to find your local guys.
I looked for other less expensive options but found nothing that was comparatively cheap enough to warrant the risk.. and these lasted about 25 years..
Job is straightforward, but access is a bear.. I think the previous owner had replaced all the bolts with stainless so there was no issue with seized and rusty stuff. I measured the old ones carefully from the base to the top of the lower nut and pre-set the new ones before installation.. I used a small scissors jack to lift the front then the back to get the old ones out and put the new ones in place.. The coupling has to be unbolted before beginning.. After replacement, a full alignment has to happen being careful to turn the jack nuts on the engine ends the same number of turns.. (turn both fronts same and turn both backs the same but will be different from fronts)..Took me about 6 hours from start to finish..

 

[Rocket1]

RE: 3GMF mounts

Excellent! Thanks for the information. My local Yanmar guy wants almost $600 for all four mounts. Ouch! However, I have friends in other parts of the country that may be able to do significantly better than that, then ship me the mounts.

Access on my 340, thankfully, appears to be pretty good. You mentioned that you haven't run it yet. Please let us know if you notice a significant improvement in noise / vibration.

How close were you able to get the alignment?

Thanks again,

 

[kloudie1]

I find that the distributors are better about not gouging you.. You guys are closer to Japan than I am so they should be cheaper..??
I got it to around 3 thousandths , but I was a machinery Injun-Ear in a former life and taught alignment of pumps and things.. The alignment took longer than replacing all mounts. The rubbers are going to settle a bit so I'll be doing that again in about 50 running hours.

 

[Benny17441]

Excellent post Kloudie. Did the totalled mounts look bad from the onset or it took a closer inspection to determine they were shot? Out of curiosity were the bad ones front, rear/ port or starboard?

 

[Scott T-Bird]

That photo shows quite a height difference between a new mount and the old saggy one. I asked Mack Boring about mounts when I was at the Newport boat show because I replaced mine about 5 years ago and thought maybe I could save money with using the recently installed mounts when re-powring this winter. They suggested that mounts should be changed far more often on a maintenance schedule than people normally do. I don't remember the bill but I think I paid about $350 for four new mounts ... it couldn't have been as high as $600, but the size probably does make a difference in price!

 

[Ken13559]

Any suggestion on how many running hours or how many years before mount should changed?

 

[kloudie1]

i think the official Yanmar list price is about $395 for theset; two 100# rated fronts and the two 75# rated aft pair. I have been watching mine slowly sag since I bought the boat in 1991. I suspect that they should have been changed about 5-8 years ago when I noted some heavy bumping noises at certain rpm ranges..I figured one or more of the mounts upper plate was bumping the top of the inverted "V" of the lower plates.. Two of the mounts do show a lot of contact there where it is metal-to-metal.. Worst mounts were right front and right rear..I suspect run time is not the problem, and it is more things like occasional diesel splashes on that side where the heat seems to be worse. The box gets really hot inside after a long (4-5 hours, and more) motor run, and I think that is as much a problem as load on the mounts. The plates and rubbers are all still firmly attached and I don't see a lot of external damage, mostly just sag.
I kept the alignment correct as the mounts sagged so the new mounts should buy me a little quiet and smoother running.
It also seemed strange to worry about the last 3-4 thousandths when I can easily move the engine four or five times that much with the pressure from one finger..

 

[onecoolair]

Rusting Mounts

Are these going to rust from day one like my original yanmar mounts ?? Its hard to tell in your pictures but, I think I already see rust......Very annoying! Rust is like a mold....It will spread to other parts that would otherwise not be rusting....making for more maintinance issuies in other areas...

Finally got time to replace the engine mounts on my Yanmar 3GMF. haven't run it yet but I suspect some of the banging was the saggy, old (kinda like the owner) engine mounts.. Interesting, two were pretty good and two were totaled.. Also noted that the new fronts, 100# rated, now have a larger diameter stud than the 75# rears . The new rears are same stud size.. No mods or drilling was necessary.. but the top nut on starboard front is mighty close to the throttle cable.

 

[Steve Dion]

Oh ya! and don't get sucked into purchasing non-OEM mounts. They are considerably less expensive (CHEAPER = cheap) but you need the real thing.

 

[Ken13559]

Robert, I don't think the mount rust easily except splash by seawater. That's what happened to my starboard mount where l had bad leak from the seawater pump . The port side mount still looks as good as day one.. What if I changed just the 2pcs of starboard mounts. Any idea if this is ok?

 

[onecoolair]

The rust gets everywhere

Ken my factory yanmar mounts started rusting from day one. The rust gets everywhere. You clean them paint them then no sooner then the paint dries its time to do it again. They are now 10 years old and its really getting tiring. Other then the rust they still seem to be good. My plan is as soon as I deal with more pressing issuies and when the budget allows. Is to replace them with motor mounts that are made from a higher grade metal that as been specially treated some how or stainless. If anyone has any ideas or sources let me know.

Robert, I don't think the mount rust easily except splash by seawater. That's what happened to my starboard mount where l had bad leak from the seawater pump . The port side mount still looks as good as day one.. What if I changed just the 2pcs of starboard mounts. Any idea if this is ok?

 

[kloudie1]

My old originals have some rust, but they are structurally fine (other than saggy rubber) .. The PO had cleaned and painted them and the heavy angle irons that the mounts bolt to. That was in early 1991. I think he may have used "cold galvanizing paint" . I have kept them kinda clean but have not re-painted.. The new ones are nice and shiny black .. The thing with the OEM mounts is that they are very stiff in fore and aft direction but not so stiff in side-to-side.. allows the secondary engine vibes to be absorbed without affecting the thrust capability.. I was not able to find a non-OEM mount that I thought would work as well.. I think the possibility of other mounts with different metallurgy is pretty slim. Ya may want to paint them with a heavy zinc coat , then black again on top to retard rust.. ??

 

[onecoolair]

Thanks for the paint idea.....What I may do is remove one at a time take home and give it a throw sanding and cleaning then do something like you suggest with the paint.

My old originals have some rust, but they are structurally fine (other than saggy rubber) .. The PO had cleaned and painted them and the heavy angle irons that the mounts bolt to. That was in early 1991. I think he may have used "cold galvanizing paint" . I have kept them kinda clean but have not re-painted.. The new ones are nice and shiny black .. The thing with the OEM mounts is that they are very stiff in fore and aft direction but not so stiff in side-to-side.. allows the secondary engine vibes to be absorbed without affecting the thrust capability.. I was not able to find a non-OEM mount that I thought would work as well.. I think the possibility of other mounts with different metallurgy is pretty slim. Ya may want to paint them with a heavy zinc coat , then black again on top to retard rust.. ??

 

[Ken13559]

Thanks for the paint idea.....What I my do is remove one at a time take home and give it a throw sanding and cleaning then do something like you suggest with the paint.

Good idea. I might do just that. Remove and restore one at a time. Thanks for the idea.

 

[Ken13559]

Claude, do you have the height dimension of your new #100 & #75 engine mount? If yes perhaps I could compare this with my existing ones to see if it has sag and by how much? Thanks.

 

[kloudie1]

Ken, I don't have the dimension on hand, but I can get it for you ..

 

[Ken13559]

Clauda, thanks. Appreicate that.

 

[abaragones]

Ken, according to the seloc manual: "When the distance is 3/16 inches or less, the mount should be replaced", this is the distance between the top plate of the mount and the curvature of the inner plate (bottom of the V shape in the middle). Sorry I am not posting the picture to explain this better but not sure if it will be a copyright issue.
Hope this helps
Abe