3YM30 Engine Mounts

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The Yanmar manual says these should be changed every 1000 hours or four years, which ever is sooner. Ever the optimist, I headed off to the Yanmar website to try find the correct part numbers. Fail.

I then headed off to the local agent and asked if they could help. "I have been informed by a mechanic that the one side is stronger than the other in order to compensate for the torque when the engine is turning" says I too the salesperson. This resulted in a blank stare and a "sorry, I don't know how to look up the part numbers on the 'pooter. Just take these ones (US$600 in total) and see if they fit"? Fail.

I then asked Mr Google, who directs me to many a site including amazon (WFT??) which means I have spent enough time on the pooter to drink four cups of coffee and eat a packet of biscuits. I now have eyes like a raped owl. Fail.

The Yanmar Installation Manual isn't much help because if you have a sail drive, you use a different combination of engine mounts than if you have a gearbox and shaft, but fails to specify what the correct combinations are. Fail.

Now I am quietly confident that having spent about four hours trying to find the part numbers for the engine mounts of a 3YM30 with a SD20 saildrive, someone on here will produce the correct information within a few minutes, which goes to show that I should have spent five minutes posting a one paragraph thread in the first place. Fail
 
Last edited by a moderator:
Thank you

With a sail drive, there is only one front mount. Can I jump to the dangerous assumption that I can use the one you've specified?
 
Not sure if the GM is so different from the YM but there is no side-to-side difference on the GM.

Does the manual really say they should be changed every 1000 hours? Seems incredible, compared with a car this is about 40,000 miles. I have owned vehicles that did 150,000 miles, never changed the mountings.
 
http://www.avindustrialproducts.co.uk/

Hi-

No knowledge of your set up but whan has that stopped people commenting on forums...;)

Keep away from marine outlets seems to be the key-

http://www.avindustrialproducts.co.uk/

I use these guys. Very easy to talk to, not sales led by any means.

I'm going in person tomorrow to buy a set for a Yanmar 2QM15. £20 each!

Yanmar four times the price.

Another firm is similar.. ROBUSH? I've not use them.

No connection etc..

Nick (Rivendell)
 
Stingo,
I also read the manual, and when my fine craft reached its 4th birthday, I rang the Yanmar shop.

The thud as I hit the floor stunned was sickening.

So I went on a quest, and found this firm in Oz

http://polyflex.com.au/Mount-Systems.php

And Lo!

They make their own mounts to match Yanmar mounts.

And at around half price, I bought a set.

Now, here is the cunning bit.

I reset my original mounts and straightened it all, then measured the displacements. After resetting the engine, all seemed smoother. Well, at least it wasn't worse.

So I decided to leave the replacement for a while, as I had around 500 hours on the engine, and measured it all again on the 5th birthday.

Guess what?

No change.

6th season then?

Ermmm, no change.

So, I have a mouldering set of shiny Polyflex mounts eager to provide fine service in the suspension and control of my 3YM30, and they are still on the subs bench.

Dunno what to say really.
 
That's interesting.

My engines have about 900hrs each and one of the mounts on the stb engine has broken - hence I had them all checked by a mechanic, who informed me about the 1000hr recommended change.

I've now bought new mounts, which are going to be installed tomorrow. My wallet has taken a nasty hammering.
 
NickRobinson said:
Hi-

No knowledge of your set up but whan has that stopped people commenting on forums...;)

Keep away from marine outlets seems to be the key-

http://www.avindustrialproducts.co.uk/

I use these guys. Very easy to talk to, not sales led by any means.

I'm going in person tomorrow to buy a set for a Yanmar 2QM15. £20 each!

Yanmar four times the price.

Another firm is similar.. ROBUSH? I've not use them.

No connection etc..

Nick (Rivendell)
Click to expand...

I've also used these people and they are excellent with good prices. Used to use them a lot for industrial engines in the past so naturally used them when I wanted new engine mounts. You will find that they are used by a lot of engine suppliers for marine mounts - they just get sprayed a different colour when the whole engine is sprayed.
 
If it ain't broken, don't fix it - springs to mind.
My 3GM30 is now 1400 hours and 16 years old. Got it 2010 and never considered a change of mounts would be needed.
My former boat had a smaller Yanmar. This was overhauled at 22 years (don't know about hours, didn't have a meter) and had the mounts changed. They did not seem too bad but since the engine was out anyway...
Think I will keep an eye on my present ones and let them do their job for another (many?) years. Lots and lots of other boaty stuff to spend my cash on!
 
Leif-J said:
If it ain't broken, don't fix it - springs to mind.
My 3GM30 is now 1400 hours and 16 years old. Got it 2010 and never considered a change of mounts would be needed.
My former boat had a smaller Yanmar. This was overhauled at 22 years (don't know about hours, didn't have a meter) and had the mounts changed. They did not seem too bad but since the engine was out anyway...
Think I will keep an eye on my present ones and let them do their job for another (many?) years. Lots and lots of other boaty stuff to spend my cash on!
Click to expand...


I completely agree, I wish manufactures would allow the technician to write the manual and not the parts marketing department.
Inspect your engine mountings, check for oil contamination/impregnation of the rubber, integrity of the rubber, splits etc, integrity of the steel support element for corrosion.
Take the time to carry out an accurate shaft alignment measurement and adjustment if necessary.
Use your hard earned money to maintain or fix something else.
 
The 1GM10 mountings are different sizes, with the front being "stiffer" than the rear. Don't muddle them up.

They are "soft" (ie bouncy" mountings. If you do fit hard mountings, you'll feel it under your feet when the engine's running. I have twin flexible couplings attached to accommodate the "bounce".

They are also susceptible to deisel. One of mine separated so I had to replace all four. You can't replace one unless you can find someone to supply a "part worn" one with similar hours to the one you took off. I now have three "part worn" which will help me out if I get a repeat problem. If it's another front, then I'm back to full set replacement after that.

I have re-aligned my engine and shaft twice since installing the engine, some 12 years ago. The last time because I had to replace the mountings. Apart from any access difficulties you might have (and I have them doubled in Spades) it's a fairly straightforward exercise. I used feeler gauges and a six inch steel ruler.

I keep telling myself it's only money and nobody died. It helps.
 
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