Engine Mount

[Ken13559]

In near future, I'll probably need to change the engine mount to my 2GM20F due to corrosion of the mount. I've following questions. Appreciate some advise from forumers.
1. Can I change the mount (4 pcs) without hauling out the engine ? I would decouple the shaft from gearbox, remove the top nut from the mount and jack up the engine to clear the mount bolt one at a time. Is this doable ?
2. Can the mount be easily remove from the engine bed ? Each mount is held down by 2 hex-head bolts but I don't know what's under the bed, is it a captive nut glass into the bed ? If it is not then I'll have problem 'cos I've no access to under part of the engine bed to get to the nut.
3. Do I suppose I've to change all 4 engine mount although there're corrosions to both starboard mounts only ?

Ken
H326, s/v Millennium 2
Singapore

 

[John T1594]

I'm no expert and I'm sure others will write to give you the collective wisdom of this site. I have had the mounts changed on engines past. One of the things that a good yard will do is change out and up-size the lag screws (a.k.a. hex bolts) that hold the mounts to the bed. These are mostly just screwed into the wooden stringers that make-up the engine bed. Over the years, they can come loose and enlarge the holes in which they are mounted.
Several captains have used a large wooden 4X4 or larger across the companionway and hoisted rather than jacked the engine to lift it. As I said, wait for advice better than mine.
Good Luck

 

[Steve Dion]

Ken: If/when you replace the motor mount, be sure to replace it with the correct one from Yanmar. Some of the boats have different ones forward/aft other have different ones port/starboard.

 

[Ken13559]

Steve, I've heard of difference between fore/aft mount but not port/starbd. I'll get new mount from Yanmar so I guess it should be ok. Thanks for the heads up.

After-thought: I did remember someone mentioned as the engine turns in one direction, the centrifugal force would load more to one side of the engine, thus the mount. So I guess this could be reason for difference in mount hardness between port/starbd.

 

[Ron McCoy]

Check the Yanmar specs for your engine. Each mount has a specified number (pounds) engraved on it. Again, your Yanmar requires very specific mounts, not a generic spinoff.

 

[Dave Sharp]

Try this

Here is a cool way to lift the engine. After disconnecting the shaft flange and seperating it, put a deflated basketball under the engine oil pan. You can then raise the engine by inflating the ball. I, also recomend getting the OEM mounts.

 

[Ken13559]

Dave, good idea on using a basketball. I was just thinking how I can place a bottle jack under the engine. There isn't much clearance for it. Thanks!!
Indeed I intend to go with original Yanmar mounts.
Question, can I just change the 2 starboard side mount only? Its not as if the mounts are weak or something, its just corrosion due to salt water splashing on starboard side.

 

[André R.]

I own a H34 that had a 3GMF20 before, as for the mounts they are the same for the 2GMF20 as I heard, the back ones are 100 124772-08340 and the front ones are the 75 128270-083340. To lift your engine a short chain 1/4" with 2 shackle between the 2 supports, a "come along" (cable winch) and a 4" x 4" between the companion way or directly attached to the boom. Decouple the shaft from the gear box, and raise is slowly, you should not have to decouple the wet exhaust or any other fuel hose or wires.
Good luch.
André

 

[Ken13559]

Andre, useful info. Thanks.

Ken

 

[Maine Sail]

Dave, good idea on using a basketball. I was just thinking how I can place a bottle jack under the engine.

I use a scissor jack from a Honda Civic. You can find them at junk yards for about $2.00 - $5.00. I think the slide under height when folded is about 2"..

 

[Ken13559]

MS, I've one jack just like on photo. Thanks.
Question remains, can I just change the starboard sides ? I know for sure we usually change car shock absorber in pair i.e both rear (or front) even when only one piece is leaking/soften. All engine mount rubbers looks good and no unusual vibrations.

 

[Nereussailor]

How old are they? Most likely they all need to be replaced.

Dave

 

[Ken13559]

How old are they? Most likely they all need to be replaced.

Dave

7.5 years old. 630 hours.

 

[Nereussailor]

I wouldn't think that they would be worn out yet. as long as there's no engine oil or other fluids on them, they should still be good I think that Hunter recommends replacing them every ten years. less if they have a lot of hours on them. You're only averaging about 85 hours a year. I can't see replacing them yet. Mine were 22 years old when I replaced them. They should have been replaced a few years before that. The previous owner neglected the boat pretty bad.

Dave

 

[SamLust]

You do not need to jack up the engine. just un-bolt the "L"mount bracket from the block, R & R the mount to the bracket, and re-bolt it. I did it this way. Simple. As for the rust, I think you will find that once off of the engine it can be cleaned up and repainted. There is enough metal there so that I doubt it is realy in need of replacement, just clean-up. Unless you enjoy spending mass quantities of money that is. Bioggest reason for replacement is deteriorated rubber. That you can't clean up.

As far as the lag screws, if they have been kept reasonably dry and snug there should be no "pull-out". But still worth checking closely. If you obersize the lags youwill likely have to open up the mounts slots to accept the larger diameter. That's a place you don't want to go.

And don't forget to align the engine to the strut , stern tube and shaft.

 

[Ken13559]

Now that's an idea I can explore. Thanks Sam.
BTW what is "R&R the mount to the bracket" ?

 

[Steve Dion]

Ken:

R & R or R/R means "remove and replace"

 

[Ken13559]

oh, thanks Steve.

 

[Rick Sylvester]

I replaced mine

but since it's a different boat ('85 H40 w/4JHE) the details may be different.

The H40 has a mineshaft for a companionway and it's located directly over the engine. This allowed me to rig a hoist using the boom and the main halyard and I lifted the engine/transmission by myself in complete control. If you don't have that option and choose to jack the motor from below just be sure the contact point is sturdy. The oil pan may not be up to the task without some bracing.

You've gotten lots of good advice although I'll wager that the bolts attaching the mounts to the bed aren't likely to be lag bolts. I'd guess that they've got a flat washer, lock washer and nut underneath.

Similarly, since you've got a later model boat I'd guess that the angle iron beds (if that's what they are) are also bolted to the liner structure. If you're replacing the mounts because they've gotten showered with salt water then I'd fix that before going any farther otherwise you'll be in the same situation in a couple years and all your work will be for naught. My problems stemmed from a poorly located raw water strainer.

If the mounts are badly rusted I'll bet the beds are too. Mine were made from mild steel and were so rusted that I replaced them with stainless steel copies I had fabbed up.

Anyway, I hope this helps.

 

[Ken13559]

Re: I replaced mine

Rick, thanks for info and pics. Mine don't have metal bracket like yours. My engine sits on fibreglass bed. My concern is how is the mount bolted down to the bed. Is it "lag bolts" or machine bolt with nut glass in ?