Why does this engine sound like this?

J

just1time

Active Member
Jun 13, 2021
217
tOrOnTo, oN
Boat Info
2003 SeaRay 280 Sundancer
Engines
Twin Mercruiser Alpha Drives 4.3
Boat rides fine. But I decided to open the engine hatch while at sea to get a feel of the engines. Starboard engine sounds different from the quiet port engine. sounds abnormal.
Looking to see if anyone has any idea what I could
Look into. Hope you hear the abnormal sound am referring to in the video.

<iframe title="vimeo-player" src="https://player.vimeo.com/video/725914728?h=1112f89a6a" width="640" height="1137" frameborder="0" allowfullscreen></iframe>
 
At first I thought maybe your belt was a bit loose, or one of the pulleys is out of alignment but it might just be from the camera moving.

What is the sound you're hearing? I can't really pinpoint it. Exhaust leak? Bad idler pulley bearing?

Is the idle speed normal? 600?
 
Sounds like a bad bearing on one of the belt driven components.
 
I will take the belt off and check each pulley to see if any are the culprit.
 
I'm in the process of doing all those right now. It started with thermostat housings, circ pumps and sea pumps -- but the bearings in all 4 idlers were bad so I replaced them. They were making more of a squeal than a growl but they definitely didn't spin very easy on their own once the belt was off.
 
Phil S said:
I'm in the process of doing all those right now. It started with thermostat housings, circ pumps and sea pumps -- but the bearings in all 4 idlers were bad so I replaced them. They were making more of a squeal than a growl but they definitely didn't spin very easy on their own once the belt was off.
Click to expand...
On a scale of 1-10, how difficult would you say pulleys are to change for an average DIYer?
 
Not bad -- maybe a 5

The issues you might run into, depending upon how long they've been on there .....

One of the smaller pulleys that is smooth on the outside (near the alternator) would not slide off once the nut was off. So I needed a 3-jaw puller to get that one out.

Also where the inner race of the pulley (22) presses up against the bushing(23), it can be tough to separate those two if it's been a long time, so 22/23 together come off the bolt but then maybe some PB blaster in between. I got a couple new bushings because they were chewed up a bit. If you have a hard time there, since you're tossing the old pulley, you could knock out the bushing if you have the right diameter socket and knock it out from the front.

upload_2022-7-1_13-40-0.png


I had a lot of surface rust on the metal pulleys (alternator, crank, circ pump, power steering pump etc) and the metal brackets so I cleaned those up and painted with POR engine black.
 
Last edited:
just1time said:
On a scale of 1-10, how difficult would you say pulleys are to change for an average DIYer?
Click to expand...
7 hours. Counting the trip to the hardware store for a magnet and fishing out all the dropped parts out from under the engine. Don't ask how I know. :)
 
Golfman25 said:
7 hours. Counting the trip to the hardware store for a magnet and fishing out all the dropped parts out from under the engine. Don't ask how I know. :)
Click to expand...

That's a good point. I have a half dozen of those collapsible magentized things that look like car antennas. I drop everything in the bilge. Also get yourself one of those magnetized trays to hold nuts/bolts/washers.

The other day I disassembled a bunch of things, and I have all the fasteners in a box. I'm climbing out of the bilge ..... slip ..... and the entire GD box spills down into the bilge. I eventually got everything back :eek:
 
Talk about dropping shit. I get back from Zodiac ride just little while ago. Gas cap on engine has a spreader wire to keep it attached. I take off gas cap to add gas and kerplunk, falls in water, the spreader didn’t do its job. So pissed, borrowed long handle fishnet from dock neighbor. After half an hour of dredging, I dropped the fishnet. Now I am REALLY pissed, MFing everything, told my slip neighbor I am selling everything, zodiacs, outboard, main boat, disgusted. I pack up my stuff and head home. Before I get out marina I get a call from him. Said he went for a swim and found the gas cap and fishnet. My faith in humanity is restored.
 
I swapped the pulleys on both engines with one another.
Here is how the two engines sound after I took it for a sea trial;
With the hatch closed, you almost won't bother
Starboard
Not sure if anyone can hear it but The starboard engine has this weird clanking sound. Any idea what this could be?

Port
Minus the chirping sound which I know is definitely from the pulley since it wasn't there before the swap, the Port side I feel now has the tiny sound the starboard did.


Am going to change both idle pulleys just to be safe.Which other pulley should I change while doing this?
Any other ideas on the what the weird sounds could be coming from?
 
Last edited:
Phil S said:
Not bad -- maybe a 5

The issues you might run into, depending upon how long they've been on there .....

One of the smaller pulleys that is smooth on the outside (near the alternator) would not slide off once the nut was off. So I needed a 3-jaw puller to get that one out.

Also where the inner race of the pulley (22) presses up against the bushing(23), it can be tough to separate those two if it's been a long time, so 22/23 together come off the bolt but then maybe some PB blaster in between. I got a couple new bushings because they were chewed up a bit. If you have a hard time there, since you're tossing the old pulley, you could knock out the bushing if you have the right diameter socket and knock it out from the front.

View attachment 129791

I had a lot of surface rust on the metal pulleys (alternator, crank, circ pump, power steering pump etc) and the metal brackets so I cleaned those up and painted with POR engine black.
Click to expand...

23 came off easily for me. The idle pulley nut is what got stripped. will be changing with new. Is the smaller pulley near the alternator worth changing?
 
scoflaw said:
Dude , take the belt off and run it. Is the noise gone?
That's the starting point/
Click to expand...
Good advice. Just went and did that.
Took two videos.Both engines sounded normal...I think.

Starboard Without Serpentine Belt


Port Without Serpentine Belt




Here are the Previous Videos for comparison.
Starboard With Serpentine Belt ON

Port With Serpentine Belt ON



So?? pulleys or engine internals as cause?
 
Last edited:
Did you spin your water pump by hand with the belt off to see if you feel a grumbling bearing? Since you pulled the belt and the grumbling stopped, the only thing different is the alternator is not spinning, the engine circulation water pump is not spinning, none of the idlers are spinning, and there is no water being pushed through the engine.

All the engine internals are pushed by the timing chain, cam gears, or crank. All those are still spinning. So it seems to me the source is an external issue.

Is my logic faulty here?
 
DWABoat said:
Did you spin your water pump by hand with the belt off to see if you feel a grumbling bearing? Since you pulled the belt and the grumbling stopped, the only thing different is the alternator is not spinning, the engine circulation water pump is not spinning, none of the idlers are spinning, and there is no water being pushed through the engine.

All the engine internals are pushed by the timing chain, cam gears, or crank. All those are still spinning. So it seems to me the source is an external issue.

Is my logic faulty here?
Click to expand...
No, not at all.
 
DWABoat said:
Did you spin your water pump by hand with the belt off to see if you feel a grumbling bearing? Since you pulled the belt and the grumbling stopped, the only thing different is the alternator is not spinning, the engine circulation water pump is not spinning, none of the idlers are spinning, and there is no water being pushed through the engine.

All the engine internals are pushed by the timing chain, cam gears, or crank. All those are still spinning. So it seems to me the source is an external issue.

Is my logic faulty here?
Click to expand...

It's funny you mention this. I sent the videos to my automotive mechanic and albeit he doesn't work on boats, he replied immediately saying the clanking sound is the "water pump".
I have been doing further searches online and some state that when the water pump is bad or going bad, the pulley rolls freely or "sounds like theres rocks rolling around inside"...something which am guessing might be the sound am hearing.

I searched online and believe this is a DIY I should be a able to handle. The only question I have is since the boat runs fine without overheating, is it safe to assume the water pump might be fine and maybe an impeller pump kit is what's needed?
Maybe the ball bearings in the drive shaft of water pump are done?
So, in essence, do I change the whole water pump to be safe or just the ball bearing drive shaft assembly and impeller kit?
Also, is this a DIY that can be done with boat in water. Would really prefer not to pull the boat out for this.

Am really new to all this so please bear with me and my questions.
 
Last edited:
You must log in or register to reply here.

Forum statistics

Threads
113,154
Messages
1,427,386
Members
61,060
Latest member
Danileo
Back
Top