Wierd engine howl captured on rough idle video

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2013 Chap 270 Sig
377 Merc Mag Bravo 3
PCM-9 with catalyst
Bought in 2020, 187 hours

At the end of last year 2020, I had a chap dealer do the Mercruiser 300 hour maintenance at 275 hrs afters and having a perfect running season, but i had no maint records. The work included a tune up, oil change, impeller, belt, zinc anodes, cap and rotor. They winterized and shrink wrapped it too. It wasn't cheap!

This season 2021 the engine ran a little worse than it did before and it encountered a engine misfire alert 2 weekends after launch.

Dealer said bring it in but since I was 3 hours away I tried to solve it myself.. I bought a $100 manual. I bought fuel filters and a new cap and rotor and replaced the same parts the dealer installed in 2020. A local mechanic told me the caps are sometimes defective. I also replaced the cool fuel canister filter and a round wafer filter underneath the CF that the manual doesn't even list. It was clogged up big time and never changed.

I put some seafoam in the gas and added a half a tank of rec fuel. I couldn't get the engine to idle until it warmed up while I hand held the throttle to keep the rpms up. After it warmed up it ran about 350-400 rpms and kind of rough.

I took it out on the lake and It ran great and got right up on plane and ran about 35mph. It shut off and started fine but now the idle is really low to almost stalling.

The season ended so I took it back to the dealer who is going to put it on the scope. He wanted to replace the same parts and I had a problem with that! I am loosing my trust in this guy who may be a throw a bunch of parts at it mechanic instead of diagnosing the problem.

While trying to figure out a rough idling problem I accidentally captured a wierd howl on video that sounded like it came from the power steering pump.

At the 9 sec mark in the video you can hear a distint howl until 13 sec.

Can I get your comments on possible problems:
1. Rough idle...bad gas? New filters, treatment added. Could it be clogged injectors?
2. Engine misfire....probably a code that stayed in the PCM until dealer clears it out. Could have been a loose plug wire that I "thought" wasn't pushed on.
3. Howling sound...could it be the power steering pump? Or something else? Should I change out the fluid next year? Or maybe the pump is going bad? Or is it related to the low idle?

I appreciate all of your comments! I plan to do my own repairs but I just wanted a starting point since I had no repair records.

Thanks, Randy

 

[Doc]

Whoa. weird. I've never heard anything like that.
Hey Bt Dcotur where are you?

 

[Iggy]

I would go after the raw water pump. Is it leaking? Take the belt off and move the pully left, right, back and forth. Does it move? There should almost no play.

 

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Hi Iggy, Nothing is leaking... i will check it out... That should narrow down the search.

 

[Bt Doctur]

definitely a bearing squel unless you mean the rumbling sound. That might be the gimbal bearing

 

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Thanks, Bt Doc! I will check it out and let you all know...

 

[Janky]

I couldn't hear anything 9-13, but 13-25 I hear what sounds like an electric pump, like maybe the fuel pump? Passes my test: if you turn up the radio and don't hear/feel it, its not that bad

 

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I couldn't hear anything 9-13, but 13-25 I hear what sounds like an electric pump, like maybe the fuel pump? Passes my test: if you turn up the radio and don't hear/feel it, its not that bad

Thanks for your input. It sounded like a bearing howl to me. It only did it that one time. It seemed like it was on the power steering pump side. It's at the dealer getting winterized and I asked the mech to check it out. Ugh...the OEM PS unit is $700 so if they tell me it's that, I may wait until next season and install it myself. Wondering why it would have to be marine grade and if a auto parts pump would suffice?

Thanks and take care!

 

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Iggy mentioned the raw water pump also...

 

[Janky]

Auto parts may work but I wouldn't do it. In general they are less durable.

 

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Update: my mercruiser mechanic looked at the noise in my video, then checked the engine and said it was a howl from the fuel pump and its normal upon startup.

I like to hear your opinions in this. Thanks in advance....

 

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Auto parts may work but I wouldn't do it. In general they are less durable.

Thanks Jackie! I would be hard pressed to use auto parts in a boat for the same reason. I Just wondered about it when I looked up the prices for an OEM power steering pump and fuel pump that will make your knees buckle!