2GM engine mounts

RichH · Oct 15, 2014

Most 'marine transmission folks' recommend that the engine mounts be replaced every 5 years. The problem with engine mounts is 'creep' - permanent elastic deformation of the rubber components of the mounts. Its cheaper to replace the engine mounts than risk rebuilding the transmission ... or be ready to align and adjust the engine 'often' after that 5 year time.

Example: On the QM series of Yanmar engines, you will routinely break the mounts at about 1000+ engine hours via metal fatigue failure of the studs on the mounts.

The OEM mounts are undoubtedly a direct replacement, and a 'known quantity' of performance / in-service life for your application - by 'history'. Aftermarket mounts can be stronger and longer lasting; but, usually require that the engine be 'moved' out of the way so that one can drill new holes in the engine bed attachments - a PITA but should be considered when doing 'severe' engine work.

FWIW and other - Also, when changing the transmission oil (usually done when changing the engine oil) on most Yanmar (Kanzaki, etc.) transmissions there is a fine metallic screen (filter) that should be cleaned and the accumulated metal particles and clutch face friction materials be removed. The filter is in the transmission's oil pump circuit. Check your engines service / 'shop' manual for the location of that very important 'filter'. Dont routinely clean out that filter and have sloppy engine mounts - premature transmission failure of bearings and oil seals.

Dave602 · Oct 15, 2014

Bought my mounts from Torrenson Marine. Direct replacement, piece of cake. If your alignment is ok and you can get some good reference measurements it makes the engine alignment afterwards easier

kloudie1 · Oct 17, 2014

Dave, the mounts for your 2GMF are the same as for the 3GMF. They are marked 100 for the front two and 75 for the aft two. The Yanmar part numbers are front, 124772-08341 and for the aft ones, 128270-08340.
I changed my mounts (original since 1985) a couple of years ago and found the engine to be a lot smoother. I think one of the top plates on one mount was hitting the bottom plate because of the rubber sagging.. I used the original Yanmar mounts because even though the other aftermarket mounts were less expensive, the modifications to mount them would have brought the price to parity.. and I had experience that the Yanmar mounts would last quite a while. Expensive.. Yup ..

kloudie1 · Oct 17, 2014

Replacing the mounts was fairly quick.. I think I did all four in about 90 minutes.. Disconnect the coupling. Then I used a small scissor jack to lift the front and changed both, but left things very loose .. set that back down then jacked the rear and changed both of those.. now is when the time consuming part starts.. re-aligning the engine to the prop shaft.. That took about another 90 minutes.. Not hard, but tedious and exacting work.

mz4wheeler · Jun 26, 2015

gr8_2_av8 said:
I have noticed that there are OEM type as well as aftermarket.

I think the yanmar mounts are absurdly expensive. Can someone point me to cheaper, after-market ones that would fit a 2GM20?

Charles Erwin · Jun 26, 2015

Google this - there are plenty of motor mount pretenders

"yanmar motor mount replacement"

Meanwhile remember these words by Rich H:

"The OEM mounts are undoubtedly a direct replacement, and a 'known quantity' of performance / in-service life for your application - by 'history' Aftermarket mounts can be stronger and longer lasting; but, usually require that the engine be 'moved' out of the way so that one can drill new holes in the engine bed attachments - a PITA. . . "

Do yourself a favor and reconsider direct replacement with factory mounts. At the least talk to Tacoma Diesel. They may have a solution.

Charles

mz4wheeler · Jun 26, 2015

Charles Erwin said:
Google this - there are plenty of motor mount pretenders

"yanmar motor mount replacement"

Meanwhile remember these words by Rich H:

"The OEM mounts are undoubtedly a direct replacement, and a 'known quantity' of performance / in-service life for your application - by 'history' Aftermarket mounts can be stronger and longer lasting; but, usually require that the engine be 'moved' out of the way so that one can drill new holes in the engine bed attachments - a PITA. . . "

Do yourself a favor and reconsider direct replacement with factory mounts. At the least talk to Tacoma Diesel. They may have a solution.

Charles

Here is one for a 2GM for $48 [grin]. Now THAT is more like it (for me).

http://shop.toadmarinesupply.com/ships_store/?p=details&ident=164133

There is nothing special about these yanmar mounts. They look equivalent to the ones I had on my Ford Falcon years ago. I think it is insane to pay $250+ each.

However, I'd hate to drill new holes. Would definitely have to pre-measure.

pateco · Jun 26, 2015

mz4wheeler said:
Here is one for a 2GM for $48 [grin]. Now THAT is more like it (for me).

http://shop.toadmarinesupply.com/ships_store/?p=details&ident=164133

There is nothing special about these yanmar mounts. They look equivalent to the ones I had on my Ford Falcon years ago. I think it is insane to pay $250+ each.

However, I'd hate to drill new holes. Would definitely have to pre-measure.

Please let me know how this goes. I too wish to replace the mounts on my 2GM in a 1983 Hunter 31.

mz4wheeler · Jun 27, 2015

pateco said:
Please let me know how this goes. I too wish to replace the mounts on my 2GM in a 1983 Hunter 31.

I'm going to take some photos/measurements to make sure that those aftermarket motor mounts really match (I have my doubts).

Still confused why Yanmar has a different part numbers for front/back. Most likely, the rear mounts may be beefier because they have to support the transmission, but I'm just guessing.

Also, it IS necessary to re-align the drive shaft, which I have never done. I heard you disconnect the drive shaft flange, and tweak the engine mounts so all sides of the flange is aligned with the engine equally (as you turn the flange) within 4mm.

My engine DOES shake at low RPMs (500-600). But is this due to weak motor mounts, bad injector, bad valve? Is this common on a 2GM20F? Would replacing the mounts just be treating a symptom?

Maybe my mounts are fine. (see photo) They LOOK OK to me. It is obvious that the existing rubber is "stressed" due to the angle of engine mounting. The rear rubber is compressed while the front is stretched. Will the aftermarket mounts adapt to this angle?

How can you tell (for sure) that your motor mounts are bad, or do they just get soft and spongy over time? From what I can see, the rubber seems intact.

Also, if I replace the mounts with new ones, the shaking may reduce, but will this cause additional stress on the mounts/bolts/etc.

A lot to consider!

I may have to visit the good folks at Tacoma Diesel, as suggested earlier.

Charles Erwin · Jun 27, 2015

The standard difference is .004" = 4/1000". 4 mm would be 40 times too large.

I have an article which shows how to perform alignment correctly. The steps are tedious but you will obtain the very best alignment possible. If you are interested I will send it E mail.

Charles

Don Crowther · Jun 27, 2015

Charles;
Could you post the article here?

Don Crowther · Jun 27, 2015

Or what about these?

http://www.pyiinc.com/images/pdf/rd/R&D Marine Yanmar Engine Mounts Price List.pdf

Charles Erwin · Jun 27, 2015

Don Crowther said:
Charles;
Could you post the article here?

Can do

woodster · Jun 27, 2015

Don Crowther said:
Or what about these?

http://www.pyiinc.com/images/pdf/rd/R&D Marine Yanmar Engine Mounts Price List.pdf

after looking at these mounts it seems to me it is just as cheap to use yanmar factory mounts

Ken13559 · Jun 27, 2015

RichH said:
Most 'marine transmission ....

FWIW and other - Also, when changing the transmission oil (usually done when changing the engine oil) on most Yanmar (Kanzaki, etc.) transmissions there is a fine metallic screen (filter) that should be cleaned and the accumulated metal particles and clutch face friction materials be removed. The filter is in the transmission's oil pump circuit. Check your engines service / 'shop' manual for the location of that very important 'filter'. Dont routinely clean out that filter and have sloppy engine mounts - premature transmission failure of bearings and oil seals.

RichH, please advise where this fine metallic screen is on the KM2P? I've checked the parts catalog but don't see the screen/bolt etc...
Thanks.

mz4wheeler · Jun 27, 2015

Charles Erwin said:
Can do

Very useful. Thanks!

Daddio · Jul 19, 2015

I was looking through this post as I need to adjust the alignment on my 29.5 2GM. It looks like the mounts have sagged and the flange is now rubbing on a crossmember. Charles Erwin had mentioned an article about aligning the engine. Where can I find it? Or can someone email it to me. Thanks

RIVERCRUISER · Jul 19, 2015

Daddio said:
I was looking through this post as I need to adjust the alignment on my 29.5 2GM. It looks like the mounts have sagged and the flange is now rubbing on a crossmember. Charles Erwin had mentioned an article about aligning the engine. Where can I find it? Or can someone email it to me. Thanks

Sounds like you need to install new mounts first...

Scroll to pp. 6&7 at this link:

http://sbo.sailboatowners.com/downloads/Hunter_gen_67952932.pdf

2GM engine mounts

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