coupler replacement merc 120

[bigskiohio]

I undid some grounds,exhaust rubber coupler, water hose from drive.
Harness stayed on motor.Used engine hoist from the side and lifting straps.
Motor came out no problem. coupler was melted. I bought new coupler
only one i could find for 1982 and below chevy. The one that is onthe motor looks different alot smaller, #39856. Bolt pattern is the same length close,should work ? i installed it ,slight press fit into flywheel.old one had a press fit too. Mounts in bell housing look good. The mount in front is not tight almost like it floats the bushing bottoms out nut wont tighten any more. I am newbee to boats but i think if i had not put it off i could have done this in aday or less and had boat back up and running. Take a look at pics let me know what you think.







Photo links
http://i276.photobucket.com/albums/k...rch2009008.jpg
http://i276.photobucket.com/albums/k...rch2009013.jpg


front motor mount photos
http://i276.photobucket.com/albums/k...h2009026-1.jpg
http://i276.photobucket.com/albums/k...h2009029-2.jpg
http://i276.photobucket.com/albums/k...rch2009028.jpg

[cr2k]

The condition of the front mount is probably why the coupler went out.
Engine alignment is crucial to coupler life.

You will need an alignment tool when you get the engine in to align the engine to the drive.

There is more to it than swapping parts.

If you have to force your drive back on, parts will force thier way out.


the splines in the coupler must be in perfect alignment with the gimbal bearing and the drive.

Dont forget to use SPLINE grease on the shaft in the new coupler.

[bigskiohio]

Already have alignment shaft but need more answers on front mount, i might have to read the manual. will take front mount apart and see what is up but the bushing under fiber washer bottoms out.

[jerryjerry05]

That cou[ler is the WRONG one.Any Mercruiser dealer should be able to get the right stuff.They also can sell you the parts to rebuild the front mount.J

[bigskiohio]

Did some looking last night there was a early small coupler and a bigger one
later but they interchange. From flange to start of coupler is the same height.
Not possible to get small early one. They are interchangeable is all that i could find out. small one part # brings up very little on google and no place to purchase. Will let you know on front mount.

[Don S]

Replace the rear motor mounts also. They also cause couplers to fail. I would never consider replacing a coupler without replacing the rear mounts. For the simple fact that you have to remove the engine to replace them. You already have the engine out. Why do it twice?

[bigskiohio]

I was going to look and see if i could find some locally today.Any idea on cost?
I am going to read my manual today on replacing them amd the front one.
Info on the coupler i bought is this.

This BRAND-NEW COUPLE replaces Mercruiser PN 76850A 2. It fits all Chevy (GM) engines that used a 2-piece rear main seal (All Chevy V8's 1985 and before are 2-piece).

If also fits the Chevy (GM) inline engines 1984 and before that did not use a "triangular" coupler.

Here is a listing of applications for Mercruiser

110 HP Serial No's 1537370 - 2044030

120 HP Serial No's 1537370 - 6229717

140 HP Serial No's 2508261-6229717

140 HP (6 cyl) Serial No's 1538930-1725960

[bigskiohio]

very little info on mounts in factory manual ,anybody have any info antwhere on these. my rear mouts in bell housing seem really solid so if i cant find any today will probably chance it and install tomorrow. boat is used less then 2 weeks a year. the front mount in manual gives no info at all except adjustment info.
in picture in manual it shows a gap too, so not sure on that . any pictures of yours would be of great help. i am thinkink gap might come out on adjustment or
that it is just for side support and up and down adjustment it gives no torque specs for top nut on mount.

[bigskiohio]

took front motor mount off and it feels very solid, the fiber washers will never seat as the spacer bushing tightens up first just like the rear mounts. does anybody have any clear instructions on this. i will take it to merc dealer tomorrow if he is there or monday to get it looked at,reason it looks like it is off center is the weight of motor was on it pushing forward on the roll cart it was sitting on.Any info would help.