1997 Merc. 40 HP Upper motor mounts

[Brian_113]

I have a 1997 mercury outboard with some slop in the upper mounts. It appears there is a rubber cover that is meant to allow some movement but how much is too much?

I can move the motor forward and back at the upper mount about 1/2". Is that OK?

 

[carholme]

Re: 1997 Merc. 40 HP Upper motor mounts

I don't see any specs for play in the service manual but with 1/2" you are going to be exerting a lot of force/wear on the grease seals and bushings in the swivel bracket. If it were mine, I would be changing the mount.

Do you have the s/n of your engine?

Gerry

 

[Brian_113]

Re: 1997 Merc. 40 HP Upper motor mounts

The serial number is: 0G476563


None of the slop is in the swivel bracket, all of the movement is purely in the upper rubber mounts.

How long of a job would you estimate that to be?

 

[carholme]

Re: 1997 Merc. 40 HP Upper motor mounts

That s/n comes up as:

MERCURY - ( 40 H.P. (1997 ))
Serial No: 0G476563 Model No: 1040412TD

Parts and Service Bulletin list for s/n 0G476563:

Search Results - Crowley Marine

The service manual you require is P/N: 90-814676. If you do not have this manual, see my message to you in Notifications at the top of this page.

The play on the bushings and seals may not be felt yet but it will be the longer you continue operations with weak mounts and it will eventually weaken the lower mounts. Depending on your experience, 3-6 hours, start to finish, depending on what you find.

Gerry

 

[DCROC]

Re: 1997 Merc. 40 HP Upper motor mounts

That s/n comes up as:

MERCURY - ( 40 H.P. (1997 ))
Serial No: 0G476563 Model No: 1040412TD

Parts and Service Bulletin list for s/n 0G476563:

Search Results - Crowley Marine

The service manual you require is P/N: 90-814676. If you do not have this manual, see my message to you in Notifications at the top of this page.

The play on the bushings and seals may not be felt yet but it will be the longer you continue operations with weak mounts and it will eventually weaken the lower mounts. Depending on your experience, 3-6 hours, start to finish, depending on what you find.

Gerry

Hi Gerry are you still on this page? I would appreciate your guidance on replacing the upper and lower mounts on the same engine as above.
Thanks
David

 

[mikevank]

is it the 40 4 cylinder 2 stroke? If so, the midplate can crack where the shifter rod goes thru it when those motor mounts get worn out. This shifter rod also ends up limiting the play when you go to check the amount of wiggle that is there so its hard to detect with out removing the lower unit. I have read they wear out much faster than other outboards, so it might be worth checking with the lower unit dropped.

 

[DCROC]

Yes it is the 4cyl 2 stroke. I think the shift shaft can't be removed without taking the powerhead off but yes it looks like the shift shaft is the only thing stopping the upper mounts separating completely. The top of the motor moves back half an inch same as OP until the shift shaft stops it.
I noticed exhaust bubbling out from around the upper mounts so there's something not right there either. Makes sense if the adapter plate has cracked.
This is a salt water engine. When I removed the shroud at top of leg, the nuts on the powerhead studs are a ball of rust and the mount bolts through the steering arm are the same. I don't think it's worth trying to get it apart with the cost of the parts it will need. That's a shame because I got it running beautifully and it's got even compression.
I bought it not running on a project boat. I got it running then stored it while I rebuilt the boat.
I cringe even mentioning this but I'm trying to think of ways I can lash it forward to the steering arm haha. This is just a little creek boat. I have an offshore boat also but can't afford to replace this engine atm.

 

[Chris1956]

Replacing the upper mounts is a major repair. You need to remove the gearcase and the powerhead. Then remove the exhaust extension to get to the mounts. You will need a powerhead base gasket and perhaps another gasket or two to reassemble.

The mounting bolts usually need to be cut off. Replace the bolts with the exact same kind, usually grade 8 fine thread steel. Also nylon locks nuts are used.

New mounts can usually be sourced from Merc or Sierra. They may be hard to get for some reason.

Check the lower mounts as well. They also can wear out.

 

[mikevank]

I did my upper motor mounts last spring, when I did a full rebuild, its pretty easy pulling everything apart. A few of the nuts for the motor studs are a pain in the ass cause you can only do a small turn at a time. Motor mounts at the time were easy to source and cheap. you will need the base gasket as well but a whole gasket set for the motor can be had for under $50 buck and then you have spares of everything. If the mid plate is cracked you can repair with some good surface prep and epoxy or JB weld. Other wise there should be a few cheap on ebay if you feel like replacing it.

As for the rust don't be too afraid. Get a map gas torch and you will be surprised how easy really corroded stuff comes apart with some heat.

If its a nice running motor its worth the few hours in my opinion.

Sorry if I'm wandering in my thoughts, I started celebrating St. Patrick's Day a bit early. lol

 

[DCROC]

Thanks for the encouragement guys. I've removed a couple of powerheads on newer engines and a mate brought his oxy gear around to get the powerhead off a 2 stroke 90hp Yamaha which turned out not worth repairing due to crank scoring.
This merc looks difficult because the nuts are half rusted away and very difficult to get a hold on or cut off.
I'll have a good think about it and price mounts and gaskets etc. I just don't want to put a grand into a $500 engine. If the gearbox or something else dies it's a waste.
It was a strong engine and a good match for the 14 foot Bertram.