Engine noise - a serious problem or not?

[ODay]

Hey Guys

I am hopeless and don't know anything about motors so I'm wondering if any of you have an idea what this noise might be:

https://www.dropbox.com/s/vivlh0cyj200t ... e.m4a?dl=0

Mercruiser 6.2 Seacore
running at idle

It has been getting louder and now there is a bit of a squeak as well.

I've booked it in for a service at the end of the month so really trying to establish if this is a problem that could get worse and either damage the engine or cause a breakdown - I am hoping I can still use it but if there is a significant issue then I will just tie it up and wait for the service.

Thanks
Mike

[ODay]

We went for a short cruise at near idle < 750rpm. The noise has become louder and changed again.

Two files, the first with the cover down the second with it up.

https://www.dropbox.com/s/gjmh3ugx6pla9 ... n.m4a?dl=0

https://www.dropbox.com/s/zo5osfd9nowi1 ... p.m4a?dl=0


Any thoughts ?

I'm tending towards caution and leaving the engine off until the mechanic can take a look.

[Titaniumboy]

Yikes. I wouldn’t run mine either with that noise.

Can you pinpoint (or at least narrow down) where the noise is coming from? Does the noise change along with the engine rpm or does the noise stay constant?

Have you sent these noise recordings to your surveyor and dealer?

[ODay]

Thanks for the reply.

No I can't figure out where it is coming from. With the cover down it is loudest at the cockpit drain near the engine compartment. With the cover up it seems to be coming from the engine - maybe the front but not sure.

Not really sure about change with engine speed. When I first noticed the noise it was quickly drowned out by the normal engine noise at higher revs. Today we stuck to low revs so not sure.

No nothing sent to dealer/surveyor yet - I thought I would wait to get confirmation on the issue. Sending to the survey could be a good idea though, I'll do that, thanks.

[billk2632]

It's hard to tell just from the sound clip, BUT it sounds like a loose exhaust flapper. If you are not familiar, that is a metal "gate" in the exhaust right where the riser connects to the Y pipe, their purpose is to prevent water from backflowing in through the exhaust. At low RPM they literally "flap" with the exhaust pulses but open fully as RPMs increase. They are prone to wear over time and come loose or wear and will start making noise. You don't say what year your boat is. If it is the flapper, it is not a serious thing at all and you can run the boat until you get it fixed. Some other possible things this could be is a loose bracket on one of the pulleys - I specifically have seen the bracket for the belt tensioner loosen on my Mercruisers. Bottom line, to me, at lease from the clip, it sounds like something external on the engine, not an internal knock or tick. I still would find the source before I run the boat.

[ODay]

Thanks, much appreciated.

The engine has done 155hrs and launch year was 2016.

I can't do anything about a faulty flapper ( the mechanic would need to look at that ) but I might be able to look at the belt tensioner bracket if the manual will tell me where it is and if I can get to it beneath the Seacore cooling parts at the top of the front of the engine. Thanks for the suggestion, I'll take a look.

[billk2632]

Realize I am just taking an educated guess from the sound:

• If it's an exhaust flapper, the sound would be coming from the rear of the engine where the exhaust risers run out of the stern of the boat. A metallic clacking that will change and probably go away as you increase engine RPMs.
  The pulley, with the engine off just grab each of the pulleys and give them a wiggle, if anything is loose it will be obvious. The tensioner is the small pulley.

Past that it could still be something minor, those are just the common / simple things I can think of.

[ODay]

Yes, thanks - understood

I started the engine just briefly this morning to try to localise the sound a little better. The sound is louder - now more of a squeak, maybe coming from about half way down the starboard side of the motor, nearer to the top. I tried to jiggle the pulleys but they seem firm to me - although the belt seems quite loose to me.

Given that the noise is getting louder I don't think we will start it again now until the mechanic gets here.

Thanks for your help.

Cheers
Mike

[Big Block Power]

Take the belt off and start it quick. Did it go away? Don't run it long I think merc runs the impeller with the belt.

[ODay]

Take the belt off and start it quick.

Thanks for the idea but that is well beyond my knowledge and skill - I can just about manage to check fluid levels

[Titaniumboy]

No, you got this. Easy peasy.

Perhaps you could add your boat and engine info to your signature?

[bruceb58]

I wonder if this is your drive input shaft tearing up your coupler.

When was the last time you had the drive removed and you checked engine drive alignment.

Now...this noise would of course be from the rear of the engine. Hard to tell from a sound file

[ODay]

No, you got this. Easy peasy.

Ha, thanks but not for me!

If this were cooking instead of mechanical repairs I would say that I can just about boil water

And more seriously, I have trouble seeing much less getting to that area of the motor ...

[ODay]

I wonder if this is your drive input shaft tearing up your coupler.

Thanks, I hope not!

The boat is new to us - we picked it up after being anti-fouled and having had a service on everything that needs working on while the boat was out of the water. So the leg, impeller whatever else they needed to do. We aim to get the rest of the service done at the end of the month. I'm going to speak to the guys that did the service today to see if they have some ideas.

[bruceb58]

I wonder if this is your drive input shaft tearing up your coupler.

Thanks, I hope not!

The boat is new to us - we picked it up after being anti-fouled and having had a service on everything that needs working on while the boat was out of the water. So the leg, impeller whatever else they needed to do. We aim to get the rest of the service done at the end of the month. I'm going to speak to the guys that did the service today to see if they have some ideas.

See if they actually pulled the drive and checked alignment.

Another thing you can do is look at the rear of the engine and look down at the drive shaft. If there was wear happening with the coupler, you will see metal dust collecting. Not sure if you can get your head back there with the charger there. If it's in the way, easy to remove temporarily.