Does the Lower engine mount wear out?

[richw46]

Just curious about the lower engine mounts. Does they wear out? My 1995 115 is going to be 29 this year and it's running fine but I notice some wobble when trailering and shaking when idling. The parts are readily available. Is it something I should be concerned with?

I believe it's like an engine mount on a car, serves a similar purpose. Would replacing them for $85 each give me any great benefit?

 

[Beachcrafter]

I'd remove them if you can, take the bolt and try to wiggle it in the mount. The rubber is likely to wear first. If it seems sloppy, replace (both, not just one)

 

[racerone]

Corrosion / rust is the culprit.

 

[richw46]

That doesn't look like an easy replacement. I thought the bolts would come out forward but the bolt starts at the aft side of the mount and goes forward, through the mount, through the bottom yoke assembly of the swivel bracket and is capped by a 3/4" nut on the end. The shifting shaft comes down through the yoke to the lower unit.

The rubber looks to be in good shape. I don't see any rot and the front part still looks glossy. There is a dusting of rust on the back area, but very little.

I think I'm going to leave well enough alone.

 

[airshot]

Just from your pics, it appears the rubber has shrunk from its housing !! Why not replace as long as you have it this far ??

 

[Faztbullet]

Fixed many just by tightening as they do work loose. I would try this first.

 

[richw46]

Thanks for the replies.
The black rubber is encircled by the metal band. I should have taken a pic of where the rubber fits inside the metal band, but it is all one piece and hasn't shrunk inside the band. I thought maybe the bolt tightening/compression on the ends may have weakened the mount's support.

There's a long bolt that goes through the length of the mount and passes through the yoke, capped by a hex nut on the end. This nut can be tightened but I must have tightened it to the max some time ago. It might be frozen too. If I try to tighten/loosen it, it may snap.

There's no way to get that bolt out of there without separating the motor from the swivel mount. There's no room to move the bolt backward. Vertically, the shifter shaft goes through the lower mount yoke also, then to the lower unit; more complexity.

I do not see any easy way to swap these out but I might soak the cap nut threads in WD40 and see if it will unscrew. If so I can then try to tighten it.

 

[Dukedog]

usually tha top mounts that go first... there is a way ta change tha bottom mounts that without all tha work.. tha hot rodder's way.. if ya interested?.. works with motors making 300+ horse power so yours would be jus fine.............

 

[Chris1956]

On my '93 Merc, the top mounts wore out. The bottom was fine. Give the motor a pull and wiggle to check the top and bottom mounts for looseness.


You might locate/price new mounts for that motor. The Merc ones were outrageously expensive, and the aftermarket (Sierra) were not plentiful. I was unable to remove the mount from the bolt due to corrosion, so the bolts needed replacement as well.

I replaced the upper mount with new from Sierra and the bolt with exactly the same kind, in this case, 7/16" fine thread grade 8 steel. The lower bolts are 1/2" fine thread grade 8 steel.

Stainless steel bolts are very likely too weak.

 

[richw46]

usually tha top mounts that go first... there is a way ta change tha bottom mounts that without all tha work.. tha hot rodder's way.. if ya interested?.. works with motors making 300+ horse power so yours would be jus fine.............

The hot rodder's way? Curious, what might that be?
My motor is no where near 300 hp but maybe you meant "up to" 300.

I'm going to guess that you mean cut the bolt and install a new one backwards.

 

[richw46]

On my '93 Merc, the top mounts wore out. The bottom was fine. Give the motor a pull and wiggle to check the top and bottom mounts for looseness.

I don't think it's moving so much that they need replacing right now. There is some movement but it's not that far from normal. I thought that it would not be too difficult to do but now that I take a closer look it seems like quite a bit of work and beyond my skillset.

I do appreciate the knowledgeable replies.

 

[Dukedog]

The hot rodder's way? Curious, what might that be?
My motor is no where near 300 hp but maybe you meant "up to" 300.

I'm going to guess that you mean cut the bolt and install a new one backwards.

correct... we did it more for being able ta change tha tuner for testin' without pullin' tha power head at tha water....

 

[Chris1956]

The top mount requires that you remove the powerhead. Pretty serious repair for a novice.

The bottom mount requires that you remove the gearcase. You should then be able to pop the mounts out of the midsection and drop the yoke, bolts and mounts as a unit.

 

[Dukedog]

The top mount requires that you remove the powerhead. Pretty serious repair for a novice.

The bottom mount requires that you remove the gearcase. You should then be able to pop the mounts out of the midsection and drop the yoke, bolts and mounts as a unit.

won't work that way with these type mounts Chris.. PH has gotta come off for top and bottom mounts........... if merc had put tha bottom bolts in opposite tha way they are it would.....

 

[Chris1956]

So you cannot cut the lower mount bolts, drop the yoke and pry the mounts out of the midsection?

It looks like you would need to put the bolts in thru the yoke first and put the nuts on the new mounts in the midsection. I never had to change them on my V6, but it sure looks like you could do it that way.

 

[Dukedog]

no, you CAN cut tha bolts and put tha new ones in backwards... you did not mention cutting tha bolts......... thats tha hot rod/DiY'er way and not in any manuals.......

 

[Chris1956]

The last time I replaced the upper mounts in my V6, even those bolts had to be cut. The mounts had corroded to the bolts where I could not drive the cut bolt end out of the mount with a punch and vise.

I expect the lower mount bolts to be similar in their corrosion or worse.

 

[richw46]

I can rotate the bolts in place without the mount moving, so they aren't frozen together. About 7-8 years ago I had to replace the ground wire on the port side and I don't recall it being difficult to get the nut off. I may have tightened up both nuts at that time, I don't recall. There's barely enough room to get a wrench on the bolt head. I don't know how you'd cut it off and putting the bolt in backwards may not let you get a wrench on the nut. I'll try to tighten them this week to see if that can be done.

The movement I'm seeing is minor and the rubber appears to be good enough. It's just the perfectionist in me that wanted to make it better (which is the enemy of good). It runs well (now that I replaced the stator) so I'm not going to try and tackle replacing the mounts. I would probably take it to a shop and see what I could get on trade for a new one should the movement get really bad. Like Dirty Harry said in Magnum Force: "A man's gotta know his limitations"

 

[Chris1956]

OK, it sounds like a non issue..... Obviously, you have a fresh water motor.....

Just for fun, you might pop off the lower mount covers and see if the rubber in the mounts have cracks.

 

[richw46]

OK, it sounds like a non issue..... Obviously, you have a fresh water motor.....

Just for fun, you might pop off the lower mount covers and see if the rubber in the mounts have cracks.

No cracks, a dusting of rust from the bolts or metal center of the mount but very little.