Gimbal Bearing Noise?

[Twhjelmgren28]

Hey all,

It's been a while since I've posted but hoping you can help me ID a noise I'm having. First of all, it's a Mercruiser 120 from the mid-80's. Usually when it's running, there is a low purr and it sounds like you'd expect.

When I finally got it out on the water, I'm noticing a loud noise coming off the shaft - I've attached a video of the noise: View attachment VID_20210703_100555039.mp4


Because I was already in the water, I was only hearing the noise inside the engine compartment - it sounds like it's coming off the shaft out of the bottom of the engine. It's kind of a scraping noise heard above the engine. Can anyone tell me what this is? Possibly the gimbal bearing? Anything else I should look into or start by replacing that? I got this boat from my grandpa so I'm sure it's never been replaced...I'm pretty handy so it should be something I can handle but I just want to be sure I'm on the right track. Thanks for any info / advice.

 

[Bt Doctur]

gimbal bearing most likely from water intrusion,

 

[Eric 3.7LX Alpha 1]

When was the last time the drive was pulled? I'd pull the drive, stick your fingers in the gimbal bearing and give it a turn, see how the bearing feels.

 

[Twhjelmgren28]

gimbal bearing most likely from water intrusion,

When was the last time the drive was pulled? I'd pull the drive, stick your fingers in the gimbal bearing and give it a turn, see how the bearing feels.

Thanks for the responses! The drive has never been pulled as far as I know so I'll probably just pull it and replace the gimbal bearing. As far as water intrusion, should I replace anything else as well? I saw a youtube video where a guy replaced the seal behind the bearing as well. I'm sure I can probably work my way through that too if it's recommended. Any thoughts?

EDIT: Upon looking into this further, I'm thinking about just doing the "transom sealing kit" that includes the bearing, seals and billows.

 

[Eric 3.7LX Alpha 1]

Thanks for the responses! The drive has never been pulled as far as I know so I'll probably just pull it and replace the gimbal bearing. As far as water intrusion, should I replace anything else as well? I saw a youtube video where a guy replaced the seal behind the bearing as well. I'm sure I can probably work my way through that too if it's recommended. Any thoughts?

EDIT: Upon looking into this further, I'm thinking about just doing the "transom sealing kit" that includes the bearing, seals and billows.

If the drive hasn't been pulled in 10+ years, there's going to be some work there: new bellows, lower shift cable, possible gimbal bearing (if it feels bad, you will know when you turn it by hand), Complete impeller kit, shift shaft seal/bushing kit in the bellhousing all should get it back in shape.

 

[jonny rotten]

I just did an outdrive oil change today.
I was getting vibrations and noise that sounded like the gimbal bearing. The noise and vibrations are gone after the oil change
Probably had 1/3 water to oil in the drive. It's a 10 minute job and your outdrive will thank you either way. May be your issue

 

[Twhjelmgren28]

I just did an outdrive oil change today.
I was getting vibrations and noise that sounded like the gimbal bearing. The noise and vibrations are gone after the oil change
Probably had 1/3 water to oil in the drive. It's a 10 minute job and your outdrive will thank you either way. May be your issue

Thanks for the suggestion - forgot to say in my OP that the first thing I did was change the lower unit oil. It looked good and I had replaced a lot of the gaskets recently so I think that should be all set.

If the drive hasn't been pulled in 10+ years, there's going to be some work there: new bellows, lower shift cable, possible gimbal bearing (if it feels bad, you will know when you turn it by hand), Complete impeller kit, shift shaft seal/bushing kit in the bellhousing all should get it back in shape.

That's a heckuva a list and I have already purchased quite a few of those parts. I wanted to say I did put in a new impeller/water pump and gaskets on the lower unit about 3 years ago in order to fix an overheating engine.

I'm going to give a run down of what I've got going on since talking to you guys. This is probably going to turn into a gimbal / transom seal / gear shift rebuild thread. I did get the outdrive off tonight which was easier than I expected.

Here is what I have purchased so far:

-Gimbal bearing
-Gimbal bearing seal
-transom seal kit (gaskets / o-rings) and water hoses
-bellows kit
-alignment tool for gimbal bearing and seal
-As I'm typing this out, I'm also ordering the lower shift cable

The only thing I haven't looked into on your list is the shift shaft seal / bushing kit. Is that a necessity at this point? The only reason I'm asking is after purchasing the above kits and the alignment tool, I may hold off on purchases for a bit. From what I'm seeing, I'd need to purchase the shift shaft kit / bushing and an additional tool. Is that correct? I'm also unsure of where this actually goes (I've got a pretty good idea on most of the other parts listed above).

Now onto some pictures and additional questions:

Here's where I finally got the outdrive off. You guys were right regarding the water intrusion - it was pretty bad. the billows basically just disintegrated when I touched it:




The U-joints on the drive shaft are pretty rusty (obviously from the water) but they seem to move freely. I'm wondering if I can just clean the rust off and grease the heck out of it...any suggestions?



Here's a close-up of the gimbal housing. The bearing was bad - I could feel a lot of grinding when moving it with my hand. I'm hoping that was my noise issue:



This part was hanging loosely in the bottom of the gimbal housing but I'm not sure where it goes - I'm guessing it fell off the outdrive while I was pulling it out?




Thanks again for your guys' help and expertise!

 

[Eric 3.7LX Alpha 1]

Thanks for the suggestion - forgot to say in my OP that the first thing I did was change the lower unit oil. It looked good and I had replaced a lot of the gaskets recently so I think that should be all set.



That's a heckuva a list and I have already purchased quite a few of those parts. I wanted to say I did put in a new impeller/water pump and gaskets on the lower unit about 3 years ago in order to fix an overheating engine.

I'm going to give a run down of what I've got going on since talking to you guys. This is probably going to turn into a gimbal / transom seal / gear shift rebuild thread. I did get the outdrive off tonight which was easier than I expected.

Here is what I have purchased so far:

-Gimbal bearing
-Gimbal bearing seal
-transom seal kit (gaskets / o-rings) and water hoses
-bellows kit
-alignment tool for gimbal bearing and seal
-As I'm typing this out, I'm also ordering the lower shift cable

The only thing I haven't looked into on your list is the shift shaft seal / bushing kit. Is that a necessity at this point? The only reason I'm asking is after purchasing the above kits and the alignment tool, I may hold off on purchases for a bit. From what I'm seeing, I'd need to purchase the shift shaft kit / bushing and an additional tool. Is that correct? I'm also unsure of where this actually goes (I've got a pretty good idea on most of the other parts listed above).

Now onto some pictures and additional questions:

Here's where I finally got the outdrive off. You guys were right regarding the water intrusion - it was pretty bad. the billows basically just disintegrated when I touched it:

View attachment 344776


The U-joints on the drive shaft are pretty rusty (obviously from the water) but they seem to move freely. I'm wondering if I can just clean the rust off and grease the heck out of it...any suggestions?
View attachment 344777


Here's a close-up of the gimbal housing. The bearing was bad - I could feel a lot of grinding when moving it with my hand. I'm hoping that was my noise issue:
View attachment 344778


This part was hanging loosely in the bottom part of the gimbal housing but I'm not sure where it goes back - I'm guessing it fell off the outdrive while I was pulling it out?
View attachment 344780



Thanks again for your guys' help and expertise!

It looks like you have the older style shift shaft bushing/seal in the bell housing. They have been redesigned and is more beefier, it keeps water from the exhaust cavity from getting into the shift cable area. That part that fell out is the exhaust shutter. That's half of it. They do that if the engine is run without water and burn off with exhaust heat. They keep sea water from getting into the engine backwards when the engine is off.

 

[Grub54891]

I just did an outdrive oil change today.
I was getting vibrations and noise that sounded like the gimbal bearing. The noise and vibrations are gone after the oil change
Probably had 1/3 water to oil in the drive. It's a 10 minute job and your outdrive will thank you either way. May be your issue

If the oil was milky, you need a re-seal.

 

[Eric 3.7LX Alpha 1]

Merc's spec for impeller replacement is 2 years or 200 hours. Here is an attached photo of Fishermark's bellhousing with the upgraded seal/bushings so you can see the difference

 

[nola mike]

The U-joints on the drive shaft are pretty rusty (obviously from the water) but they seem to move freely. I'm wondering if I can just clean the rust off and grease the heck out of it...any suggestions?

Replace them.

 

[Paintman1960]

Replace them.

For sure ! There junk !

 

[wshekar]

Merc's spec for impeller replacement is 2 years or 200 hours. Here is an attached photo of Fishermark's bellhousing with the upgraded seal/bushings so you can see the difference

The seal/bushings can wait if finances get tight. That doesn't seem to be where the water came in from. Clearly the bellows were past due. The gimbal seal only needs to be installed if you are getting a greasable bearing. Perma-lube bearings don't need them.

 

[jonny rotten]

Don't forget to get a hinge pin tool.
Be very careful with the trim sending limit wires. There is a bracket that holds them in on top of the unit. It is literally impossible to get one of the bolts out to change the wires.
My wires turned to dust when I messed with them so bought new sending/limit switches and ended up not using them because of that one freakin bolt. Now I go by the feel of the boat which is simple enough

You can also use an " exhaust tube" instead of the exhaust bellows to make things easier

 

[nola mike]

Don't forget to get a hinge pin tool.
Be very careful with the trim sending limit wires. There is a bracket that holds them in on top of the unit. It is literally impossible to get one of the bolts out to change the wires.
My wires turned to dust when I messed with them so bought new sending/limit switches and ended up not using them because of that one freakin bolt. Now I go by the feel of the boat which is simple enough

You can also use an " exhaust tube" instead of the exhaust bellows to make things easier

An allen wrench works fine on the hinge pins, they just need heat. The trim sender bolt sucks, but it is possible. Exhaust tube makes that part of the job a non issue.

 

[Twhjelmgren28]

You guys are awesome!

It looks like you have the older style shift shaft bushing/seal in the bell housing. They have been redesigned and is more beefier, it keeps water from the exhaust cavity from getting into the shift cable area. That part that fell out is the exhaust shutter. That's half of it. They do that if the engine is run without water and burn off with exhaust heat. They keep sea water from getting into the engine backwards when the engine is off.

You all have got me convinced to just do it right and get the back end rebuilt. I'm going to get the shift shaft bushing / seal. It looks like I don't necessarily need the little tool based on some videos I watched so I'm going to skip that for now.

Can I reuse that shutter? I haven't really looked into that part of the project yet...

Replace them.

For sure ! There junk !

I'm going to replace these too - they were less expensive that I imagined. I'm also going to clean up the yoke and all those parts.

The seal/bushings can wait if finances get tight. That doesn't seem to be where the water came in from. Clearly the bellows were past due. The gimbal seal only needs to be installed if you are getting a greasable bearing. Perma-lube bearings don't need them.

I'm not entirely sure which type of bearing I got. It came in a kit...I'll wait on actually replacing the seal itself until I figure out what type of bearing I have. At least that was only $8.

Don't forget to get a hinge pin tool.
Be very careful with the trim sending limit wires. There is a bracket that holds them in on top of the unit. It is literally impossible to get one of the bolts out to change the wires.
My wires turned to dust when I messed with them so bought new sending/limit switches and ended up not using them because of that one freakin bolt. Now I go by the feel of the boat which is simple enough

You can also use an " exhaust tube" instead of the exhaust bellows to make things easier

An allen wrench works fine on the hinge pins, they just need heat. The trim sender bolt sucks, but it is possible. Exhaust tube makes that part of the job a non issue.

Thanks for the reminder on the hinge pin tool - I did get that and bellows adhesive from Amazon so I should be set there. As far as the trim wires, I'm planning on removing that plastic housing that covers the hinge pin but that's as far as I'm planning on going. Are you talking about the wires that are up inside and above the U-joint bellows? I don't plan on removing those.

I'd did get an exhaust bellows in the kit I purchased but if you guys think there is an advantage to the tube over the bellows, I'd be open to purchasing a tube as well...

 

[Twhjelmgren28]

I did look into the exhaust shutter flaps and I'm going to grab those as well - also fairly inexpensive it looks like. Now if I could just find out what happened to the other one - hopefully that one is still attached.

 

[nola mike]

You guys are awesome!



You all have got me convinced to just do it right and get the back end rebuilt. I'm going to get the shift shaft bushing / seal. It looks like I don't necessarily need the little tool based on some videos I watched so I'm going to skip that for now.

Some threaded rod, a couple of nuts and washers to use as a press.

Can I reuse that shutter? I haven't really looked into that part of the project yet...

No.

I'm going to replace these too - they were less expensive that I imagined. I'm also going to clean up the yoke and all those parts.

Moog 315g u-joints, I just ordered a couple off of amazon for $12 each

I'd did get an exhaust bellows in the kit I purchased but if you guys think there is an advantage to the tube over the bellows, I'd be open to purchasing a tube as well...

Tube is easier to install, it's a bit louder

 

[Eric 3.7LX Alpha 1]

Couple of more things to mention... if you do the shift shaft bushings/seal, you have to remove that shift arm (Mercruiser # 45518A3)
at the top of the shift shaft. There is a small set screw that holds the arm to the shaft that usually doesn't come off without damage. It's usually easier to use a small cold chisel and crack the arm off and replace it.

Also 1/2" drive 9/16" deep socket worked for me to install the new shift cable to the bellhousing, I didn't use any special tool. You can also use a 9/16" spark plug socket and then another socket off that one, see the attached video someone else made:

 

[Twhjelmgren28]

Couple of more things to mention... if you do the shift shaft bushings/seal, you have to remove that shift arm (Mercruiser # 45518A3)
at the top of the shift shaft. There is a small set screw that holds the arm to the shaft that usually doesn't come off without damage. It's usually easier to use a small cold chisel and crack the arm off and replace it.

Also 1/2" drive 9/16" deep socket worked for me to install the new shift cable to the bellhousing, I didn't use any special tool. You can also use a 9/16" spark plug socket and then another socket off that one, see the attached video someone else made:

Sorry for the late response - thanks for the tips and video!

I've already ran into that shift arm set screw - wouldn't budge. In order to get the bell housing off I ended up sawzalling through the shift cable - definitely overkill but it worked. I'll be dealing with that shift arm towards the end of the rebuild. I think I'll probably do that shift cable last.

After much persuasion from the slide hammer I was able to get the old gimbal bearing out. That was much harder than I expected. I don't think anything back there has been touched in the last 35 years.

I'm slowly but surely moving forward - have to wait for parts anyway so I'll keep you guys apprised. I'm most definitely going to need more advice / tips in the future.