Squealing noise coming from engine

RngrGrl · Jun 30, 2014

I just bought a 2000 Ranger, 204k miles.
I test drove this truck and everything seemed great, as did it while I was driving it home.
Then a couple days after I bought it I began to notice a very high-pitched squealing/chirping noise coming from somewhere near the alternator. I can't tell exactly where, whether it's the pulley or the alternator itself or something else right next to it.
It only happens after the engine has warmed up and has been running for several minutes, and only occurs when I press on the accelerator. When I let off the accelerator or idle, the engine sounds normal.

Any ideas what this could be, and if it's a serious problem or not?
Thanks!

MPRanger · Jun 30, 2014

I would say you have a loose/worn out pulley. What I did to narrow it down was go one pulley at a time with WD-40 and spray the bearing (be careful not to hit the belt) and see if that makes the noise go away/get better.

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Rearanger · Jun 30, 2014

WD-40 is not a lubricant.

Kowboy · Jun 30, 2014

I'd guess the Cam Positioning Sensor if you have the 3.0 V6 engine. It'll sound like it's coming from the alternator, but may not be. The CPS is located on the passenger side of the engine close to the firewall and nearly out of sight.

alwaysFlOoReD · Jun 30, 2014

What engine?

A mechanics stethoscope is handy for isolating where the sound is coming from. A short piece of garden hose can do the same; stick one end of ~ 4' garden hose to ear and poke the other end close to where you suspect the noise is coming from. Be careful of moving parts.
Good luck,

Richard

RngrGrl · Jun 30, 2014

It's a 3.0 V6.

bucko · Jul 1, 2014

I've used a broken handle of a garden tool as a way to identify where a noise is coming from. I place one end at my ear, the other on the alternator, the A/C compressor, and other pulleys. Be careful of course. The garden hose is another good idea as well.

I too have squirted a shot of WD-40 around the area of a pulley, or on the A/C clutch to see if a squeal goes away. It's only temporary, but it identifys the culprit.

My dad used to hold a bar of soap on the undersides of a belt to see if they were the sause of a squeal. The soap lubricates the underside of the belt, which in turn is what contacts the pulley surface. If the squeal stopped, the belt was slipping and the cause of the squeal.

The Cam sensor is known to make a squeal sound as weel, and is sometimes blamed for 3.0 noises and poor performance. At 204K, I'd say its safe that the cam sensor has been replaced at least once on that engine; they are considered a maintenance item to be replaced every 80 to 100K. If you listen carefully for a squeal towards the rear center of the engine (engine to firewall area), you should be able to rule it out as a source of the squeal.

MPRanger · Jul 1, 2014

bucko said:
I too have squirted a shot of WD-40 around the area of a pulley, or on the A/C clutch to see if a squeal goes away. It's only temporary, but it identifys the culprit.

Exactly.

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sblake01 · Jul 1, 2014

Kowboy said:
I'd guess the Cam Positioning Sensor if you have the 3.0 V6 engine. It'll sound like it's coming from the alternator, but may not be. The CPS is located on the passenger side of the engine close to the firewall and nearly out of sight.

It's actually the synchronizer that the camshaft position sensor mounts on the can develop a squeal. See this link:

http://www.therangerstation.com/tech_library/camshaft_position_sensor.shtml

2813josh · Jul 1, 2014

sblake01 said:
It's actually the synchronizer that the camshaft position sensor mounts on the can develop a squeal. See this link:

http://www.therangerstation.com/tech_library/camshaft_position_sensor.shtml

Yes,this is what I would suspect. Seems to be quite common on the 3.0.

Bronco638 · Jul 2, 2014

Could also be a water pump bearing. It's a common Ford issue.

Rearanger · Jul 2, 2014

Lots of possibles. Best advice is using a hose to listen at each component. I find a stethoscope too sensitive as it picks up all sounds - close and far.

bucko · Jul 3, 2014

2813josh said:
Yes,this is what I would suspect. Seems to be quite common on the 3.0.

Easy enough to rule out (or "in") by simply removing the two long screws that hold the sensor on the shaft, and inspecting the condition of the "tab"; if it appears to have any wear, then the complete assembly needs replacement.

Also, an indication of it's beginning to fail is longer start issues. If the engine cranks for more than a few seconds, I'd inspect for this tab wear.

sblake01 · Jul 3, 2014

bucko said:
Easy enough to rule out (or "in") by simply removing the two long screws that hold the sensor on the shaft, and inspecting the condition of the "tab"; if it appears to have any wear, then the complete assembly needs replacement.

Also, an indication of it's beginning to fail is longer start issues. If the engine cranks for more than a few seconds, I'd inspect for this tab wear.

The 'tab' being worn, while it would cause other problems such as you mention, it wouldn't be the cause of the noise. The 'squeal' would be coming from the bearing that the shaft rides in.

MA Ranger · Jul 7, 2014

You may want to check the alternator by turning the pulley with the belt off. Do the same with the idler pulley, water pump pulley and belt tensioner pulley. If they all seem o.k., check the "tensioner" on the belt tensioner by observing its motion when the engine is running (with the belt back on) and the noise is present. If the noise you're hearing is in sync with the "back and forth motion" of the tensioner, it may be the cause of the noise.

Squealing noise coming from engine

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