5.0 L Merc engine coupler problem

[fsamie1]

just replaced the triangular coupler and try to use the alignment tool to line up the engine. With front mounts at lowest position, the tool goes in not too easy but not too tough either. Grease marking shows better contact at the top. When I turn the engine 120 degrees, the tool only goes in about one inch and good contact at the top again. Same thing, when I turn crank 240 degree. This tells me that coupler is not centered on the flywheel. I put it in with three rubber things that supposed to center it and bolt it on. What did I miss? Going to pull it out again to check the coupling location on the flywheel. What a lousy design, Merc engineers could have centered the coupler many other simpler and easier way that using those three rubber junk. It is no fun to pull engine out twice with a cherry picker inside the boat. I wonderd anybody else had similar problem? Any help is appreciated. What did I do wrong? Thanks.

 

[Bt Doctur]

Re: 5.0 L Merc engine coupler problem

The question is why did it go bad, simply replacing the coupler will not fix a bad rear mount bushings or loose /rotted front mounts.

 

[300sflyer]

Re: 5.0 L Merc engine coupler problem

just replaced the triangular coupler and try to use the alignment tool to line up the engine. With front mounts at lowest position, the tool goes in not too easy but not too tough either. Grease marking shows better contact at the top. When I turn the engine 120 degrees, the tool only goes in about one inch and good contact at the top again. Same thing, when I turn crank 240 degree. This tells me that coupler is not centered on the flywheel. I put it in with three rubber things that supposed to center it and bolt it on. What did I miss? Going to pull it out again to check the coupling location on the flywheel. What a lousy design, Merc engineers could have centered the coupler many other simpler and easier way that using those three rubber junk. It is no fun to pull engine out twice with a cherry picker inside the boat. I wonderd anybody else had similar problem? Any help is appreciated. What did I do wrong? Thanks.

It's possible you have a defective coupler. I bought two remanufactured engines from Merc, both with brand new couplers. One was fine, the other was defective as the splines were not centered in the rubber. While turning the engine over with the starter, one could watch the splines wobble around with a flashlight shining through the gimble bearing. It was replaced by Merc at N/C.

 

[fsamie1]

Re: 5.0 L Merc engine coupler problem

Engine mounts are fine and wood is not rotted. It lasted 20 years and wnt thru lots of trolling for salmon and walleye. I guess some misalignment caused the faliure.
I bought a new Merc coupler and shaft for 350 dollars and planning to remove it this weekend to see if it is bad. that is a good explanation for all problems I am having. I hope I did not bend the coupler while installing the engine.

 

[Bt Doctur]

Re: 5.0 L Merc engine coupler problem

Kinda hard to bend it with the drive off when you install a motor.

 

[muc]

Re: 5.0 L Merc engine coupler problem

Mercruiser came out with service bulletin 2009-11 on coupler replacement.
It talks about installing coupler with taper head screws first than replacing those screws one at a time.
Might be good to check flywheel run-out also.
Good Luck Muc

 

[fsamie1]

Re: 5.0 L Merc engine coupler problem

Thanks Muc, where can I find a copy of service bulletin 2009-11 on coupler replacement? Taper head screw? where cam I buy them? Thanks

 

[Bifflefan]

Re: 5.0 L Merc engine coupler problem

Just FYI, If the grease markes are always on the top then the front is to low.
You said that the front was all the way down, raise it up some and try again.

 

[fsamie1]

Re: 5.0 L Merc engine coupler problem

Front mounts are all way down and top of the coupler (12 o'clock) has a good contact with the alignment tool. Therefore, if I raise the front mounts, top of the coupler will move down and interfere more with the alignment tool.

 

[Alpheus]

Re: 5.0 L Merc engine coupler problem

Just FYI, If the grease markes are always on the top then the front is to low.
You said that the front was all the way down, raise it up some and try again.

Wrong. Heavy spline marks on top= front to high...

http://forums.iboats.com/showthread.php?t=436175&highlight=proper+alignment+tool

http://forums.iboats.com/showthread.php?t=421602

 

[fsamie1]

Re: 5.0 L Merc engine coupler problem

Just measured the out of the coupler runout next to grease fitting using an indicator and it measured 0.040 inch. Is this too much? This is just the outter diameter, do not know if spline in centered.
Also compared the rear mount inner ring heights, one is sitting 0.090 higher. I am sure this will screw up side to side alignment.
Here is the master plan, I do not know what else to do: Remove the engine, center the coupling somehow, or get another new coupling, and change rear mounts.
do not mean to offend anybody, but this merc design and engineering is just idiotic. Never buy another one again.

 

[fsamie1]

Re: 5.0 L Merc engine coupler problem

took the engine out again, One rear mount is bad, it is sitting 2 mm lower than the other since the rubber is broken. Removed the coupler, it is not bent. Put is back on more carefully this time to make sure it is centered on flywheel. measured the runout on outer soupling shaft next to grease fitting, it was the same as before 0.040 inches. Tried to put alignment tool and the shaft in there in to measure spline runout, but it was not possible because there was some play and was not getting consistent measurement. Do I have a bad coupling? Thanks guys.

 

[300sflyer]

Re: 5.0 L Merc engine coupler problem

took the engine out again, One rear mount is bad, it is sitting 2 mm lower than the other since the rubber is broken. Removed the coupler, it is not bent. Put is back on more carefully this time to make sure it is centered on flywheel. measured the runout on outer soupling shaft next to grease fitting, it was the same as before 0.040 inches. Tried to put alignment tool and the shaft in there in to measure spline runout, but it was not possible because there was some play and was not getting consistent measurement. Do I have a bad coupling? Thanks guys.

Since no one else has replied, Im going to take a stab at it, and say yes... I think .040 is too much runout. So how much is acceptable? Not sure... Perhaps a call to Mercury Marine will get you a more definative answer.

BTW... You never stated if the new coupler was an OEM one or some other company?

 

[seaphase]

Re: 5.0 L Merc engine coupler problem

You're not alone fsamie1. I have a brand new engine, new inner transom assembly, new rear motor mounts, new front motor mounts, and just bolted on a new coupler and put engine in and it wouldn't line up. My stringers are in good shape and I have new 2x4's that are securely fastened to my stringers that the new front motor mounts are setting on. After hours of trying to align it, I finally got it close, turned the engine over and it gets tight as he.. again. So, figure my new coupler is bad. I then sanded down a 3/4" piece of PVC so it would fit inside the coupler and not touch the gimbal bearing to see the orientation of the coupler to the gimbal bearing. When i turn the engine over with the piece of PVC in the coupler, the PVC wobbles quite a bit. Got a new coupler coming and gonna take the engine out again. Also gonna check the run-out on the flywheel and on the new coupler that I currently have on there. Will see what happens next.