Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha One

[oldjeep]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

Sounds like valve train to me. Sticky lifter or loose rocker arm

 

[Bondo]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

I don't think a detonation / pre-ignition could do that kind of noise, not that loud though... It's coming from the flywheel zone, not the head.

Ayuh,... If yer that Sure, Pull the motor, 'n See what came loose,...

All this Guessin', ain't gettin' ya nowhere,...

 

[smassey22180]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

I would start with one of these Lisle 52500 Mechanic's Stethoscope : Amazon.com : Automotive Or a long piece of hose that can be used to listen in. But since the boat is moving around the hose may need a person holding each end in place. Probe around the engine until you find the loudest point. From your video it sounded like the rocker arms to me. But that is just a wag. Pinging would be loudest just below the head gasket in the block.

 

[thecca]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

So a rocker arm can work normally but be bad under load? Because the issue ain't there when the motor is idling / not accelerating

 

[oldjeep]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

So a rocker arm can work normally but be bad under load? Because the issue ain't there when the motor is idling / not accelerating (planing)

Lifter/rocker arm noise is more RPM based than load based.

 

[thecca]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

...

 

[thecca]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

That's what I thought... I dont think this is the problem either. I've noticed the fuel filter isn't full of gas even when running. Is this normal or it's supposed to always be full with no air in it?

 

[oldjeep]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

What kind of fuel filter do you have that you can see the gas in it?

 

[thecca]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

A clear one. On the video I posted with the issue you can see it.

 

[oldjeep]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

A clear one. On the video I posted with the issue you can see it.

Wow - you added one of those plastic things before the actual pump and filter? Pretty sure those are not USCG approved. Why did that get added anyways?

Edit 0:46 in the video

 

[thecca]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

I didn't add anything, I bought the boat like this about 2 months ago and a maintenance was done (about 2000$) last february by previous owner (new gimball bearing, new carburetor, new plugs, new fuel filter, new thermostat housing, new exhaust manifold).

It's not supposed to be there?...

 

[oldjeep]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

I didn't add anything, I bought the boat like this about 2 months ago and a maintenance was done (about 2000$) last february by previous owner (new gimball bearing, new carburetor, new plugs, new fuel filter, new thermostat housing, new exhaust manifold).

It's not supposed to be there?...

Nope

 

[thecca]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

Then why it's there? Could that cause restriction and make my engine run leaner and create the noise? I ran the boat for a month or two with this setup before my issue began...

 

[oldjeep]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

Then why it's there? Could that cause restriction and make my engine run leaner and create the noise? I ran the boat for a month or two with this setup before my issue began...

Doubt it is causing any problems at the moment, but it makes me wonder if they changed the filter that is in the pump and why they thought adding that was a good idea. The danger in those things is cracking and filling the bilge with fuel.

Here is a vid on changing the fuel filter on the pump.
Replacing In-pump Fuel Filter - 96' Mercruiser 3.0lx - YouTube

 

[smassey22180]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

An easy test for rocker arm noise would be to remove the oil cap, run the engine and listen.

 

[ktbarrentine]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

Shutters?

 

[thecca]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

May-be shutters, but engine don't overheat and has no power loss... the issue is more often present when I accelerate and push the throttle back a bit (decceleration)

 

[ktbarrentine]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

Shutters wouldnt affect engine temp or power....but would make tink-tink-tink type metalic noise when wearing out (metal to metal rattle). Just another guess..... (from my experience, the noise is mostly at idle).

 

[81 Checkmate]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

You eliminated the octane issue??? So Did ya check the flywheel?

Did ya check with a stethoscope to pinpoint the area?

Pop the valve cover off and look at the rockers.

It aint gona go away???Need to find the issue before something lets loose!

 

[thecca]

Re: Strange noise coming from motor under acceleration... Mercruiser 3.0 with Alpha O

Shutters wouldnt affect engine temp or power....but would make tink-tink-tink type metalic noise when wearing out (metal to metal rattle). Just another guess..... (from my experience, the noise is mostly at idle).

Mercruiser 3.0L (2000) with Alpha One - Weird noise (clang / rattle) under acceleration - YouTube check at 1:35. This sounds like metal to metal to me... I fear it might get worst if I continue riding my boat like this and the noise isn't there unless I put load on the motor.