mercruiser 120 major issues

[newmaac]

1969 Mercriser 120 I/O

New, first time boat owners, (son's boat)
We found the wood beam that supports the front motor mount to be completely rotten.
Replaced the wood, but didn't align the motor mount.

Started and ran the motor, to work-out some fuel issues, but heard what I can only describe a pretty serious rubbing noise. Couldn't tell if it was from the motor or the out drive.

Son wanted to put it in the water anyway, just to see if it even ran before spending any more time/money.

At the dock, the motor ran OK, but seemed to be struggling, and the "rubbing was pretty bad. "
Found that the out drive wouldn't engage.
After about two minutes of trying the 'rubbing" stopped, (we finally broke it), the engine smoothed out, and we have NO drive, forward or reverse.

Doing some reading online, I assume that we wrecked the gimbal bearing??
Would a severely misaligned motor cause enough friction to make the out drive completely fail, or does that sound like a separate, non related issue?
in many of the forums that I have been associated with, this is where I expect to be "flamed" for being so stupid, and not listening to obvious clues that the machine was trying to tell us.
I would appreciate any/ all advice that you might want to share.
Thanks in advance

 

[Sjharleymc]

Mercruiser 120 drive problem

Mercruiser 120 drive problem

Hi I am new to the forums. Just bought a 69 starcraft with a 120 inboard outboard. Took the boat out for the first time today. When we had the motor idleing we could hear a vibration and the boat was not wanting to reverse. I tried to put the boat in gear to leave the dock the vibration was gone but the boat would not move. Tried forward and reverse but nothing happened.
Not familiar with these at all so any suggestions will help. Thanks

 

[stonyloam]

Re: mercruiser 120 major issues

It sounds like the coupler may have failed due to the fact that the motor was not aligned before you ran it. Start it on muffs and see if the driveshaft behind the engine is turning Do not run it for more than 30 seconds or so, you do not want it to overheat and add to your problems), I suspect it is not. No flames here, I learned by making one mistake after another. If driveshaft is not turning, plan on removing the outdrive. Lots of help here. Let us know what you find. Good luck. Remember it is not like a car, the driveshaft turns all the time, in gear or not, so if it is misaligned the damage will be done simply by running the engine.

 

[stonyloam]

Re: Mercruiser 120 drive problem

Re: Mercruiser 120 drive problem

Just read your dad's post, sounds like a failed coupler due to misalignment after the engine mount repair.

 

[Sjharleymc]

Re: mercruiser 120 major issues

Thanks. We removed the outdrive as soon as we got home. Not sure what to look for. the u-joint is intact and still spins the prop by hand. Should we replace the gimble while we are in here? And if so where can we find the tools to remove and replace it?

 

[Eric 3.7LX Alpha 1]

Re: mercruiser 120 major issues

Welcome!!

Stick you fingers inside the gimbal bearing and rotate it by hand. "Feel" how it turns. Is it silky smooth or does it feel rough when you turn it? you will know if it's shot trust me.

The thing that gets damaged majority of the time alignment is off is the coupler. It's bolted to the flywheel at the back of the engine.

Did you have any metal shavings at all on the splines when you removed the drive?
Did you smell rubber burning at all from inside the boat.
If the gears in the upper half of the outdrive are shot I would guess it could make a pretty bad sound as well.

Try and looking thru the center of the gimbal bearing with a light and look at the splines on the coupler which is bolted to the back of the engine. You could also remove the top cover on the drive (4-3/8" 12 corner bolts) and have a look at the upper gears..... you'll need a new gasket if you do though.

 

[achris]

Re: Mercruiser 120 drive problem

Re: Mercruiser 120 drive problem

2 threads on the same issue on the same boat....

http://forums.iboats.com/mercruiser...iser-120-major-issues-625458.html#post4359673

 

[Eric 3.7LX Alpha 1]

Re: Mercruiser 120 drive problem

Re: Mercruiser 120 drive problem

I already commented in his.....

That would be pretty funny if you guys both signed up here and posted about your troubles without either knowing that the other was doing the same thing

 

[Sjharleymc]

Re: Mercruiser 120 drive problem

Re: Mercruiser 120 drive problem

Yep both posted from different houses at the same time not knowing it. I will delete this thread

 

[Bondo]

Re: Mercruiser 120 drive problem

Re: Mercruiser 120 drive problem

Yep both posted from different houses at the same time not knowing it. I will delete this thread

Ayuh,.... This is Too Funny of a story to deleted, 'n You can't anyways,...

Both of ya's postin' in the Same minute no less,...

I merged the two threads together,...

Welcome Aboard,.....

 

[Sjharleymc]

Re: Mercruiser 120 drive problem

Re: Mercruiser 120 drive problem

thanks, no metal on the shaft when we removed it. i will be checking the gimble bearing at lunch today. how difficult is it to replace the coupler?

 

[stonyloam]

Re: Mercruiser 120 drive problem

Re: Mercruiser 120 drive problem

how difficult is it to replace the coupler?

With the outdrive off, you have to lift the engine and move it forward enough to access the bolts that hold the coupler to the flywheel. You will need a Mercruiser alignment tool, e-bay for about $35.