4.3GL Motor Making Low Rumble Noise - Have Video w/sound

[MAW31]

I am attempting to identify the noise this motor is making. It has not run for almost 2 years and for almost 4 weeks, I had been starting and idling the motor only, I had replaced the impeller, changed the Oil, emptied, then filled gas tank, fresh plugs etc. So after 2 weeks of simple 15 min. idling, I put the motor in reverse at idle speed while lowered in the slip, but not off the lift so the outdrive could get some spin-time. all low rpm actions. Oil pressure was steady at 40psi. I'm in Florida so water isn't considered 'cccold'. and the motor was purring. the idle was a bit high at around 1200 rpm but not real high.

the noise started after I did a run-up to maybe 1800 rpm since we were prepping for our first idle-speed run.. I have not yet studied the outdrive nor checked the foot oil. and have not moved the boat from its lift/slip. While at this short but steady rpm run-up, the sound suddenly began and has not stopped since.

I fear a bearing had spun, but am told the noise would be higher pitched and the oil pressure would have dropped off noticeably. I can service the outdrive next if you think it might be a bearing there. but if the motor is shot, I'm done with my project boat.

Would you mind listening to the video and help me figure out what the most likely cause is?

FYI: While attempting to nail down the noise, I took off all the belts so only the crank was spinning and the noise was not abated. (only for like 10 seconds) but that at least told me is wasn't a bearing set on the alternator, water pump, or steering pump.

 

[bruceb58]

Your video is set to private.

 

[MAW31]

Thank you. this was my first upload to youtube. I published the video so I hope you can see it now.

 

[Bondo]

I have not yet studied the outdrive nor checked the foot oil.

Ayuh,.... I can't really hear anything that jumps out at me,....

Much of the drive turns with the crankshaft,.... I'd start there, atleast check the oil,.....

 

[bruceb58]

Pull the drive and feed water from a hose into the water inlet hose and try it.

 

[Lou C]

Are you sure it's not the front circulation pump, when mine wore out it sounded just like that.
Go back around the transom and listen for noise from the gimble/U joint area...

 

[MAW31]

I have removed the foot before, but not the gimble housing. This boat is on a dock lift and I can float another boat under it to remove the outdrive for inspection.
Thank you all for your input. I will proceed to the outdrive and report my findings.

 

[bruceb58]

Are you sure it's not the front circulation pump, when mine wore out it sounded just like that.

He did take off all the belts and said noise was the same.

 

[Grub54891]

When you pull the drive, reach in and spin the gimble bearing by hand. It should feel smooth and nice. If not it'll rumble.

 

[MAW31]

No Title

Whew, it was a bit difficult on the dock lift, but the outdrive is now off!
The Universal joint/knuckle was super greased and appeared to be ok. some water was sitting on the bottom of the bellows boot and when I spun the gimbal bearing with my fingers...well, it wasn't the 'smoking gun' of evidence that I was hoping for. Was it perfectly smooth? No. Did it spin with little resistance? yes. I guess for the noise volume that was being made that the bearing would have been in poor poor shape. I am headed shortly to Harbor Freight to get a bearing puller and once removed, will order the bearing and seal.

 

[bruceb58]

Run it with the drive off while you feed the engine water to see if the noise is gone.

 

[Grub54891]

I'd be a tad concerned about the water in the bellow. Check it real good for cracking or wear. Possibly the big o-ring was bad too.

 

[bruceb58]

I agree....I would be concerned with the water in there as well.

The gimbal bearing needs to be perfectly smooth.

I would be replacing the u-joint bellows for sure.

 

[MAW31]

Started the motor with no outdrive and a water source and voila! noise is gone. Now to the bearing swap and reassembly. quick question: all things being the same, if I removed the outdrive, and replace the bearing; the drive shaft and motor would still be aligned, yes? I don't have an alignment tool that I read about but if the gimbal mount is not altered, then the outdrive shaft should simply slide back in. also, what exactly can the 'alignment bar' do to adjust the position anyway, its not gonna move the motor around is it?

 

[bruceb58]

Buy an alignment tool. You will need to set the angle of the new gimbal bearing to the coupler plus you should be checking it every time you remove the drive since the front engine mount/stringer height can change over time.

 

[MAW31]

i'll get the alignment tool then.

 

[MAW31]

The Gimbal Bearing is out. Good thing too, lots of shrapnel was ground into the bearing. Anywho...no-where and I mean no where is there any part number on this bearing. I did a search on "Volvo Penta SX Gimbal Bearing" and places like "wholesale marine" return 4 different bearings that all look like they could work.
This boat is a 1997 Regal LSR2100 with a 4.3GL motor and a Volvo SX Cobra outdrive.
Thoughts?
I did measure the bearing: 88mm OD, 35mm ID, 26mm deep. It has a removable shield on the outer edge. and a round dot on the casing edge.

 

[bruceb58]

There are all sorts of equivalent bearings. Here is one:
http://www.iboats.com/Sierra-18-2100...view_id.187590

The OEM numbers are 3853408 or 21752712
here is an OEM:
http://www.ebay.com/itm/New-OEM-Volv...dW6B5n&vxp=mtr

http://www.ebay.com/sch/i.html?_from...52712&_sacat=0

 

[bruceb58]

You should be replacing the U-joint bellows too. Make sure you get an OEM bellows.

 

[MAW31]

No Title

thank you so much! i took photos, so i might as well post em. the casing was in horrible shape.