Mercruiser 5.7/Bravo 1 - Clanking Sound from Rear of Engine

[WiredLlama]

Noticed a clanking type sound coming from the rear of the engine over the weekend. I am thinking u-joint, gimbal, or possibly the coupler. Can anyone lend some advice on the potential source of the sound?

My fear is that it is the coupler. I greased the gimbal on the outdrive zerk fitting and one of the zerk fittings on the coupler. I then ran the engine for a few seconds to get access to the second zerk fitting on the coupler. I then ran the boat again and the clanking noise decreased significantly (but is still audible). Any insight or experience in diagnosing this sound is very much appreciated. I have gained a lot of knowledge from creeping around these forums but this is my first post.

sound before I greased any fittings: https://youtu.be/U7E8wb5rJQ4

sound after I greased the gimbal and both coupler fittings: https://youtu.be/lfYTVT9qhO4

 

[Bt Doctur]

pull the drive and look, simply adding grease to change a clanking sound is never good. odd are good its a bag gimbal bearing
from lack of grease or water intrusion Depending on your year the gimbal is 18-2100 or 15-21005 or permalube 18-21001

 

[Scott Danforth]

pull the drive. AND LOOK

its an annual maintenance requirement anyway

 

[WiredLlama]

I plan on pulling the drive but can't do it for another day or two. I am just trying to get a feel of what I may be encountering when it comes off. I figured the grease reducing the sound was just a temporary band aid masking the real problem. We have a long weekend lake trip at the end of the month so I am hoping I don't find anything that's going to kill that weekend.

The boat is a '99 Crownline 225br. New to me this year and judging by how this summer is going I don't think the previous owner did any maintenance or he just sold it at the right time. New raw water pump (pulley seized and burnt the serpentine belt off), new serpentine belt, new circulating pump, new alternator, now this sound...

 

[alldodge]

The drive is heavy and have help if you can, or at least a block of wood just below the drive so it hits it instead of something hard. Raise the drive before removing anything to disconnect the speedometer tube. There is a rubber tube which connects to the top of the cavitation plate. Rotate the lever 45 degrees and then pull it straight out.

Now lower drive and remove the rear trim rams and six bolts. The shifter just needs to be in neutral. It will come out about and inch and then raise the keeper holding the shift cable (starboard side), then remove drive the rest of the way. Comes off easy enough.

If you have not drained and refilled the drive do it now, and check engine alignment

 

[WiredLlama]

Thanks for the tips! I watched a youtube video and the removal seems pretty simple.

I plan on removing it with a buddy who has pulled his numerous times before. He also has the alignment tool. Hopefully it's a relatively easy fix. I am just keeping my fingers crossed that it doesn't have to do with the coupler. In anyone's experience is the coupler prone to issues or is it more than likely the gimbal bearing or u-joint? I can't help but stressing out about this until I can get the drive off and see what's going on.

 

[alldodge]

My first guess its the gimbal bearing, don't see it being the coupler IMO

 

[Rick Stephens]

Is it possible it is just the exhaust shutters rattling? Might run it and use a dowel to listen for where the noise is coming from.

 

[WiredLlama]

Yea I did the ole screwdriver stethascope and it seemed to me the source was coming from the gimbal housing area or the upper drive shaft housing area. No unusual noises in the exhaust tubes from what I could tell. Thanks for the idea!

 

[Rick Stephens]

Yea I did the ole screwdriver stethascope and it seemed to me the source was coming from the gimbal housing area or the upper drive shaft housing area. No unusual noises in the exhaust tubes from what I could tell. Thanks for the idea!

There you go. A step ahead of me. Time to pull the drive. Once you have done that it won't bother you doing it ever again.

 

[WiredLlama]

pulling the drive tomorrow night. Fingers crossed. I have a terrible feeling about this but nothing I can do but fix whatever is broken at this point.

 

[WiredLlama]

My first guess its the gimbal bearing, don't see it being the coupler IMO

So when I tear this thing apart this evening I more than likely going to need to order some parts. My biggest trouble with boat stuff is finding correct part numbers. Can anyone link me to a good parts diagram with part numbers that I can reference so I can quickly order what I need tonight? Closest boat shop is about 45 minutes away and I hate to just call parts departments to ask about part numbers and then not order anything from them. I suppose I am probably looking for the u-joint part numbers, gimbal bearing part numbers, and (worst case scenario) coupler part number.

1999 5.7 Mercruiser ( s/n OL087607)
Bravo One (s/n OL160420)

Thanks! What a great resource this forum is and especially the regulars who routinely help newer/young guys like me. Awesome.

 

[Rick Stephens]

Try this for the motor

http://www.iboats.com/5-7L-2-BBL-GM-350-V-8-0L010037-THRU-0M599999/dm/view_id.1683713


I can never find the sectional drawings at iboats. Maybe one of the others can. I use a different website to find part numbers and often order from iBoats by searching for that part number. I hate linking other sites, but I flat cannot find the exploded parts diagrams for drives at iBoats.

 

[alldodge]

Here is the drive shaft, and also check in the Adults Only area for U joint numbers to use which will cost less
http://www.mercruiserparts.com/bam/subassembly/30967/1943/210

Gimbal housing
http://www.mercruiserparts.com/bam/subassembly/30967/1943/160

Bell housing boots
http://www.mercruiserparts.com/bam/subassembly/30967/1943/180

This is listing for the entire drive
http://www.mercruiserparts.com/bravo-one-0f730000-thru-0m100000

 

[WiredLlama]

thanks, those links are very useful!

 

[H20Rat]

So when I tear this thing apart this evening I more than likely going to need to order some parts.

You will also need the gasket kit. My luck is that I almost always need it if I remove the drive, it tends to stick and rip.

 

[WiredLlama]

You will also need the gasket kit. My luck is that I almost always need it if I remove the drive, it tends to stick and rip.

thanks for the reminder! Got one on it's way in the mail already

 

[WiredLlama]

Quick question; If the splines on the driveshaft look good does that mean that most likely the coupler splines are in good shape? Or not necessarily? The gimbal bearing seems to have a slight notch in one spot though. though. Possible issue causing the noise?

Still waiting to check the alignement.

 

[alldodge]

Quick question; If the splines on the driveshaft look good does that mean that most likely the coupler splines are in good shape? Or not necessarily? The gimbal bearing seems to have a slight notch in one spot though. though. Possible issue causing the noise?

Still waiting to check the alignment.

No, the drive shaft is Rockwell hardened and the coupler is not. The coupler is the sacrificial item which is used to protect the drive and the motor. Look inside at the coupler splines and the pattern should match the drive shaft. If the squared off slots look a little like pointed mountains, then the shaft has been wearing the coupler. The coupler below is new. If the points were sharp points then it would be bad

 

[WiredLlama]

Makes sense. Just wanted to make sure. I'll have to peek in a little further. Gotta find a better flashlight. Thanks