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Help me diagnose a squealing problem 2007 7.4

N

ni7irs

New member
I have a I/O 2000 7.4L MPI sterndrive. I have a rather loud squeel between 2250-4000 RPM. I changed the belt, tightened the idler, listened with a mechanics stethoscope, but cant seem to find the source. The squeal is loud enough to hear with the engine compartment closed but pretty loud with it open.

Everything spins free with the belt off. Also, curiously, the noise is only there when the prop is engaged and the boat is moving forward. If I rev it up in neutral to 2000-4000 rpm, no noise. I dont understand how it can be there when the engine is turning the prop, but not when its idle. RPM's are RPM's right? If the alternator was doing it, would it matter if the engine was under load or not? how would the alternator or power steering know?
 
Re: Help me diagnose a squealing problem

Best guess: Harmonic balancer is starting to go bad.
 
Re: Help me diagnose a squealing problem

yank the prop off see any fishing line wrapped around the shaft? I might be so melted that it may appear as a plastck washer, you must remove it or risk the seal.

And believe me the seal will go.

Aword of advice i always remove my prop in my driveway after going on the water to inspect the shaft and then i shoot the shaft, with corrosion pro or i get out the grease gun to put a light coat of grease on the splines, i have seen too many props frozen on splines in my years. Any can grease will do ask Bond-o he may say " any grease is better then no grease "

Ok maybe it's not the prop. But then it may be the gimbal bearing. When was the alignment checked last?

Finally all the above is good that squealing is still telling you something.

The belt looks good ? No black dust appearing in the bilge you can't account for. The pulleys rusty ?

Have someone else drive the boat and when you hear the squealing and your sure it's coming from the motor and not behind it ?

You have a coupler behind the motor talking to you maybe ? Thats the alignment issue ?

You asked how the power steering would know, or the alternator.

The more power demanded as more speed and force is applied then more force must be applied to counter the force applied. So power steering pump could be going or may need a power steering fluid change, may be as simple as that.

The same for the alternator. My alternator on my current boat went it started freezing and eating the belt. 2 belts went without the belt it spun easy but underway and power was demanded from it it would freeze a second and unfreeze i watched it with my own eyes.

Db electrical sent me one 100 amps i think it was 70 bucks delivered.

bye the way my friend went thru 2 power steering pumps on his 7.4 l crownline till finally we left it off.
 
Re: Help me diagnose a squealing problem

OK, let me see if I can answer these. Prop and sterndrive were just off. Mechanic said that everything was fine and the alignment was straight. The sound seems to come from the front of the engine.

Belt is brand new. Some conditioner sprayed on it lessened the noise. I guess the power steering might be a likely culprit. You think that changing that oil might be the problem?

Should I take the alternator off and have it tested?

What is the web site address for DB?
 
Re: Help me diagnose a squealing problem

Altenator or power steering pump........

Surpentine belt drive systems are different than v belt systems.

The pullies used can cause a sqeaking noise even though there is no issue with the device it is attached to.

If you can, spray some wd 40 or something similar at the pullies one at a time (alt, power steering, water pump), and see if you can localize the noise by quieting it down.

I had an alternator pully that had worn down some of its grooves inside the pully and it squealed.

Try to isolate it more before just swapping stuff around.....
 
Re: Help me diagnose a squealing problem

You could check the alternator pulley nut to be sure it hasn't loosened up. Had one do that once, drove me nuts trying to figure out why the thing wouldn't charge at start up but began charging shortly after running it.
Bert
 
Re: Help me diagnose a squealing problem

I sprayed belt conditioner on the belt which helped a little. I just can't get around the issue that there is no squeal when its in neutral. Some people mentioned harmonic balancer, is that difficult to fix r replace?
 
Re: Help me diagnose a squealing problem

Eyeball the belt/pulleys from the side. Make sure that all the pulleys and accessories are in the same plane, i.e. that none of the pulleys or accessory drive pulleys are either in front of or behind the others.
 
Re: Help me diagnose a squealing problem

you can have the alternator teested at auto zone for free. Why buy one if not needed .
My money is really on the power steering pump. is it low on fluid? A fluid change is cheap and then again do you have a power steering fluid cooler?
 
Re: Help me diagnose a squealing problem

sandkicker said:
Eyeball the belt/pulleys from the side. Make sure that all the pulleys and accessories are in the same plane, i.e. that none of the pulleys or accessory drive pulleys are either in front of or behind the others.
Click to expand...

The idler looks like its out of plane/cocked a little.
 
Re: Help me diagnose a squealing problem

chiefalen said:
you can have the alternator teested at auto zone for free. Why buy one if not needed .
My money is really on the power steering pump. is it low on fluid? A fluid change is cheap and then again do you have a power steering fluid cooler?
Click to expand...


The fluid looks ok on PS, I dont think it has a cooler. Why woudlnt it squeal when its in neutral? The PS pump isnt under a load unless you are turning the steering wheel right?
 
Re: Help me diagnose a squealing problem

ni7irs

I was thinking about this yesterday and I think we need more info

You say no noise in neutral, Only in gear correct?

Can you try to pin point the source of the noise a bit closer than just from the engine?

Front of the engine?, rear of the engine??? left side? right side?

Transom?

Due to your not so specific location we all seem to be suggesting a belt/pully issues.

Can you try to get a better location and try to give us more info all at one time.

Thanks....
 
Re: Help me diagnose a squealing problem

kghost said:
ni7irs

I was thinking about this yesterday and I think we need more info

You say no noise in neutral, Only in gear correct?

Can you try to pin point the source of the noise a bit closer than just from the engine?

Front of the engine?, rear of the engine??? left side? right side?

Transom?

Due to your not so specific location we all seem to be suggesting a belt/pully issues.

Can you try to get a better location and try to give us more info all at one time.

Thanks....
Click to expand...


First, let me say thanks to everyone for their interest in my problem. The folks on this site are by far the most helkpful and knowledgeable.

As for the sound, it definately sounds like it is at the front of the engine. As for pinpointing it, I cant. It doesnt seem to be coming from the back. The one other thing I would like to point out is that it is not like your traditional belt squeal that you would get on a car in the morning when the belts are going bad.

This is something that peaks at 2,500 and then slowly builds to a peak and constant noise until 4000 RPM.

I am starting to wonder whether it wouldnt be better described as a high pitched whistle which has me wondering if I should take off the flame arrestor and give it a good soak. When I winterized the boat, the flame arrester was filthy, but I only cleaned the front and sprayed it with WD40. Perhaps i should soak it thouroughly?

Maybe its a high pithced whistle caused by an air obstruction? When the engine is working hard its sucking more gas and air, so maybe thats why its only when its in gear?

I am also goign to buy a new tensioner. Its only $12 at the auto parts store and it does look a little kinked. Thanks again everyone and keep your thoughts coming.
 
Re: Help me diagnose a squealing problem

Get some carb or brake cleaner and clean the flame arrestor. (take it off the engine first). Blow from inside to out.
Can't say for sure that it's the source of the noise, but you can at least eliminate it, and it needs done anyway.
The WD40 film will actually encourage dirt to stick to it. Needs to be degreased thouroughly!
 
Re: Help me diagnose a squealing problem

Remove the belt and check the circulating water pump shaft for side-to-side play, in-and-out play and turn it by hand to feel for a rough dry bearing.
 
Re: Help me diagnose a squealing problem

look for a disconnected or cracked vacuum hose, you don't have too many.

when they come loose you can get a high pitched whistle when under load. Seen similar sequence of events with intake manifold leaks, too.
 
This is the exact same description of whats happening on my 454 in a Baja...did you ever figure it out?


ni7irs said:
I have a I/O 2000 7.4L MPI sterndrive. I have a rather loud squeel between 2250-4000 RPM. I changed the belt, tightened the idler, listened with a mechanics stethoscope, but cant seem to find the source. The squeal is loud enough to hear with the engine compartment closed but pretty loud with it open.

Everything spins free with the belt off. Also, curiously, the noise is only there when the prop is engaged and the boat is moving forward. If I rev it up in neutral to 2000-4000 rpm, no noise. I dont understand how it can be there when the engine is turning the prop, but not when its idle. RPM's are RPM's right? If the alternator was doing it, would it matter if the engine was under load or not? how would the alternator or power steering know?
Click to expand...
 
That noise reminds me of my old Volvo-Penta drive. It its case, it was coming from the upper gearbox and it was gear noise. It did it only in gear, and was louder at speed. Sound familiar?

Jeff
 
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