Knocking/Squeaking sound back of engine

[jim98zj]

2001 SeaRay 240 Sundeck
5.7 mercruiser with Bravor 3
650 hrs

Previous owner neglected this boat and I'm pretty sure it sank on land given all the random things I've had to replace.

Now that I've got it running it's making a squeak and knocking/pinging sound. The knock came first and then after running it a bit more the squeak started. Sound seems to be coming from the back of the engine and possibly the port side. I can feel the knock anywhere in the engine and it increases with RPMs. The Bravo3 shifts smoothly fwd and reverse. The sound is while in gear or out.

I have looked in each cylinder and not found anything unexpected, I have pulled the port valve cover and everything looks good while running. It really doesnt sound like an exhaust leak. I'm thinking something on the back end but haven't pulled the drive yet. Hoping somebody can see in these videos below something familiar so I can go right to fixing instead of wasting more time diagnosing.

https://youtube.com/shorts/o4BZGJHX5g0?feature=share

https://youtube.com/shorts/eJpFhpNv5Dw?feature=share

Thanks in advance.

 

[Nater Potater]

'Hate to troubleshoot something like that over the internet, but, with it tending to be noisiest towards the transom, I'd be for pulling the outdrive and checking the gimbal bearing. However, you may find that you have a number of gremlins. You might pick up a cheap stethoscope from an auto parts store and do some probing.

 

[Lazy Daze]

Sounds can bounce around and make it (like Nater pointed out) hard to diagnose via a forum. Remove that serp belt and run for about 15 to 30 seconds to see if any sounds go away or change. Depending on what you notice, repeat with the drive off.

A cheap mechanics stethoscope as Mr. Idaho mentioned is a cheap tool that can do wonders. A long wooden dowel or or long screwdriver can also be used.

 

[Nater Potater]

A cheap mechanics stethoscope as Mr. Idaho mentioned is a cheap tool that can do wonders. A long wooden dowel or or long screwdriver can also be used.

I didn't think to mention that a two-foot chunk of broom handle has been my go-to for the better part of fifty years. It just seems a bit too ghetto! It's pretty impressive the sounds you can isolate with something like that.

 

[jim98zj]

I didn't think to mention that a two-foot chunk of broom handle has been my go-to for the better part of fifty years. It just seems a bit too ghetto! It's pretty impressive the sounds you can isolate with something like that.

Amazon is sending me a seal kit and a couple u-joints Tuesday so I'll pull the outdrive Wednesday and fingers crossed it is the u-joints. If not I can always return them but at least I can run the engine a few seconds isolated from the drive to better pinpoint the bouse. If I have time I'll use my tiny scope to try and inspect the u-joints tomorrow from inside. Thanks for the recommendations so far!

 

[Nater Potater]

Amazon is sending me a seal kit and a couple u-joints Tuesday so I'll pull the outdrive Wednesday and fingers crossed it is the u-joints.

Sweet! I didn't think to have you steer the outdrive full left to right while running. That would help point out bad u-joints.

...but at least I can run the engine a few seconds isolated from the drive to better pinpoint the noise.

Assuming you do (and you should), pop the serpentine first so as not to smoke the seawater pump's rubber impeller.

 

[ttmott]

Amazon is sending me a seal kit and a couple u-joints Tuesday so I'll pull the outdrive Wednesday and fingers crossed it is the u-joints. If not I can always return them but at least I can run the engine a few seconds isolated from the drive to better pinpoint the bouse. If I have time I'll use my tiny scope to try and inspect the u-joints tomorrow from inside. Thanks for the recommendations so far!

If you are in that deep, might as well replace the stuff anyway.
Like my neighbor tearing the front end of his old Astrovan apart to change the water pump but didn't change the belts or hoses - guess what he had to do a week later.

 

[jim98zj]

If you are in that deep, might as well replace the stuff anyway.
Like my neighbor tearing the front end of his old Astrovan apart to change the water pump but didn't change the belts or hoses - guess what he had to do a week later.

That's what I figured on doing. Thanks!

 

[boatrboy]

FWIW - I have run my bravo3 without the drive installed. You can shove a cut off water hose in the inlet and either tie wrap it to the nearest stud or have someone hold it while you run the motor.

 

[Espos4]

If you are in that deep, might as well replace the stuff anyway.
Like my neighbor tearing the front end of his old Astrovan apart to change the water pump but didn't change the belts or hoses - guess what he had to do a week later.

Lemme guess………..See a chiropractor because there is no way an average size person can comfortably contort themselves to fix anything on an Astro Van??

 

[ttmott]

Lemme guess………..See a chiropractor because there is no way an average size person can comfortably contort themselves to fix anything on an Astro Van??

Yea it was hilarious - the entire front end of the van was in the driveway - grill, radiator, AC condenser, fan shroud, bumper, etc.
One week later that front end was on the driveway again. I distinctly mentioned he should replace the hoses and belts while he was that far down....

 

[jim98zj]

Lemme guess………..See a chiropractor because there is no way an average size person can comfortably contort themselves to fix anything on an Astro Van??

This sounds like when I dropped my favorite 1/4 ratchet and it fell underneath the engine behind the motor mount yesterday. No man left behind!

 

[ttmott]

OK so you want a good one?
I rebuilt my neighbor's old 225 HP Merc OB. If you've ever had one apart, you know all of the bearings are tiny needle roller bearings, hundreds of them. I lay everything out and count the bearings on a clean towel on the work bench so everything going into the motor is accounted for. One missed needle bearing will cause the engine to self-destruct - not negotiable. Worked all night and got the motor back together. Next morning another friend was over and as a joke took a used needle bearing out of the garbage and placed it on that towel where I had all of the parts arranged. He forgot and didn't tell me - I tore that entire engine back apart that day to resolve the mystery. He called later that day to tell me what he had done -laughing; that is until he found out I had torn the engine back down. He did amp up another gasket kit.

 

[Lazy Daze]

You're not running the engine with the drive tilted up, are you?

 

[jim98zj]

You're not running the engine with the drive tilted up, are you?

Negative. It was stored fairly high up for 2 years tho which is why I'm hoping the u-joints got kinda locked in a funny position.

 

[Fill Ess]

OK so you want a good one?
I rebuilt my neighbor's old 225 HP Merc OB. If you've ever had one apart, you know all of the bearings are tiny needle roller bearings, hundreds of them. I lay everything out and count the bearings on a clean towel on the work bench so everything going into the motor is accounted for. One missed needle bearing will cause the engine to self-destruct - not negotiable. Worked all night and got the motor back together. Next morning another friend was over and as a joke took a used needle bearing out of the garbage and placed it on that towel where I had all of the parts arranged. He forgot and didn't tell me - I tore that entire engine back apart that day to resolve the mystery. He called later that day to tell me what he had done -laughing; that is until he found out I had torn the engine back down. He did amp up another gasket kit.

I hope you beat him senseless -- and then said just kidding

 

[jim98zj]

Update

Pulled the lower unit and ran it for a few seconds. Noise is still there. I have new u-joints and a u-joint press tool but I couldn't bring myself to changing them because they look brand new and are very free moving. Replaced the seals and put the lower unit back on.

It still sounds like it's coming from the back of the engine so I'm going to use the old wooden dowel and a flash light to see if I can narrow down the location. It sounds so much like something hitting a loose shroud while spinning that I have to think it's something stupid and easy to fix once I find it.

 

[Espos4]

Re read post #6. Did you run it briefly with the serpentine belt removed?

It’s simple to do and will rule out (or confirm) some common causes of noise.

 

[jim98zj]

Re read post #6. Did you run it briefly with the serpentine belt removed?

It’s simple to do and will rule out (or confirm) some common causes of noise.

Not yet but I will momentarily. I didn't dismiss it, just knew I had to take it off later anyway to put that seal in the seawater pump that I forgot when rebuilding it