Belt chirp/squeal

[Phil]

1994 4.0L auto
*in a buggy

I have:
PSC power steering pump (~10 years old but trail only)
Alternator (rebuilt maybe 2022?)
Smooth idler pulley
Water pump (replaced 2024)
Harmonic balancer/crankshaft (OEM)

There’s an annoying chirp/squeal.

Belt is newer (less than 100 hours/4 years). Good tension per cricket gauge. 140-160#.

I bought a mechanic stethoscope from harbor freight but can’t pinpoint any cause.

Sometimes the noise is there constantly, sometimes it goes away at idle and only is audible at higher loads/revs.

Any guidance other than “turn the radio up”?

Thanks

Phil

 

[RCP Phx]

I don't see the fan bearing on your list?

 

[75SV1]

Also, check the AC clutch. Mark the Harmonic balancer with white paint. Just one stripe between the hub and the outer ring.

 

[Phil]

I don't see the fan bearing on your list?

No mechanical fan, no mechanical fan mount, newer SPAL electric fan but it chirps with the electric fan off.

Also, check the AC clutch. Mark the Harmonic balancer with white paint. Just one stripe between the hub and the outer ring.

No AC pump/clutch/system/objects.

My eyes don’t move fast enough to correlate the sound with the rotation of the stripe but a slo-mo video on the phone says inconclusive as well. Or are you suggesting slippage on the balancer?

 

[75SV1]

Slippage of the balancer. Also, what brand of serpentine belt?

 

[tommyr]

Spray the belt with water. That will temporarily quiet a noisy belt. Still squeaking, check other pullies.

 

[Phil]

Water does silence it and it comes back with a vengeance as it starts to dry. It is just I think a NAPA belt right now. I can throw a Gates at it.

 

[75SV1]

Water does silence it and it comes back with a vengeance as it starts to dry. It is just I think a NAPA belt right now. I can throw a Gates at it.

NAPA had or has two grades of belts. My local NAPA stopped carrying the lower end belt. I think Gates also has a few choices. I think HD and High RPM. Also, some like Continental. I have a Conti somewhere. It was hanging on the wall at a local Import Auto store. I remember it also fits a MB 450SL or such. I think I use the Gates HD. Its green on the outside.

 

[Unclewolverine]

Mine has the spring tensioner, and when it started chirping the solution was simply a new belt. Silicone spray would make it go away for a bit, but only a new belt solved it. At only a hundred hours, but 4 years of age I bet the rubber is getting on the hard side.

 

[Jeep ride 2nd]

Don't know about now when I worked at Napa their first line belts and hoses were made by gates fwiw.

 

[Phil]

This is killing me. I put on a new Goodyear 1060710 last night, about 190-200# per the Krikut gauge, and it is still chirping.

No visible relative movement on the harmonic balancer witness line, all pulleys feel smooth.

Not sure how else to diagnose this. Don’t really want to throw more and more different belts at it and there are not that many moving parts.

 

[lawsoncl]

Are all the pulley faces parallel if you lay a straight edge across them? Having one of the smooth pulleys slightly crooked will squeal.

 

[Phil]

Are all the pulley faces parallel if you lay a straight edge across them? Having one of the smooth pulleys slightly crooked will squeal.

None of them seem to be exactly planar but they appear to be maintaining a similar gap from the straight edge to face of back-set pulley.

The harmonic balancer - which does not appear to wobble - is close to the block, like 1/16” or a little wider than a sawzall metal-cutting blade, so I wonder if that is a symptom? Does not appear to wobble or slip.

 

[XJ_ranger]

Rock auto lists the most expensive Harmonic balancer as $64 and the cheapest as $32.

The smooth pulley and bearing is much cheaper and easier to change, ranging from $8 to $23 in rock auto.

For less than $100 you could change the two remaining parts.
I can also send you a spare PSC pump you could try if you wanted.

 

[Phil]

Well at least access is pretty good. I’ll throw a harmonic balancer at it after the next trip. Probably the nicest one NAPA has or can get in a day or two.