Metallic screeching from under the hood

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I drove 104 miles round trip today all highway (pay road 80 mph all the way). Near the end of my trip I started noticing intermittent metallic screeching from under the hood. It would start and last about 3 minutes at 75-80 mph and then go away. I don't hear it at idle or can't duplicate in the garage. It seems to screech under load and higher speed only. Could this be idler pulley, fan clutch or anything more serious? Should I be concerned?

 

[delloro]

My first guess is an idler or tensioning pulley, followed by alternator.

 

[fkheath]

My first guess is an idler or tensioning pulley, followed by alternator.

Also, a glazed serpentine/accessory belt can sequel like that. Try some belt conditioner on it. Most likely a bearing like delloro said -- don't forget the A/C compressor bearings and power steering pump bearings too.

 

[flyrv9]

I'd take off the serpentine belt and spin all the pulleys by hand. They should all spin freely and not bind. You should not feel any grinding either. Also check that they don't wobble or have side to side play. Also check the belt for cracks and glazing. The last time I had this problem, it was due to a bad bearing in the Alternator in my old Nissan PU. I couldn't find a rebuild kit; so I had to replace it.

 

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I released tension pulley with 14mm and regular 3/8 drive handle which seem to move easily, should there be a lot of tension? Also both No2 Idler pulleys seem to wobble some. I will check alternator, AC and Power Steering pulleys once I get new Idler ones. I did notice that my fan spins but doesn't seem to put out enough force (not as loud as before), is there a way to test if fan clutch gone bad?

 

[JLTD]

Pulleys should not wobble.

 

[MicrowaveOven]

Pulleys should turn smoothly. If it spins like a n old skateboard wheel, and sounds like one, they could be replaced.


Sent from my iPhone using Tapatalk Pro

 

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I ordered 2 idler pulleys fan clutch and new belt. I will check other pulleys once I've those parts. My fan is inconsistent, I could spin it freely and easily after long highway drive but after short drive it acts normally by spinning with little resistance. Can fan clutch be intermittently faulty?

 

[delloro]

Can fan clutch be intermittently faulty?

As I recall, fan clutches spin more freely when cool, less freely when hot.

 

[flyrv9]

A bad fan clutch can also result in high coolant temp or overheating - are you experiencing that? Also I suggest you get an OEM serpentine belt. It may cost a bit more, and worth it IMHO. There have been issues with aftermarket belts not really being the right size and or not wearing well.

 

[Mack1611]

Has anyone seen the cat recently?

 

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Haven't seen damn cat but annoyed to hell with this metallic noise. 40K on odometer and I'm hunting for something faulty screeching an speed. I thought Toyota should be reliable.

 

[jp.vegas]

As I recall, fan clutches spin more freely when cool, less freely when hot.

Correct. That's how the clutch works on a normally operating fan.

 

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It seems that source of screeching is a drivetrain. Transfer case output bearing or seal? I hear it at higher speeds and can not duplicate at idle. Any ideas?

 

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This one lil more severe than my but same screech:
High-Pitched Squealing Noise - '16 Limited | Toyota 4Runner Forum [4Runners.com]

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