SOHC Belt Squeal

[schaffnerb]

Hi guys,

It's been a while since I posted with a problem.

Here goes.

I have a 2000 SOHC explorer that squeals on startup, as well as idle. It squeals at idle only with my lights and blower on. During the squeal my battery gauge will drop. Once I give it gas the gauge returns to normal and the squeal works itself out. IF the lights and blower are not on it will not squeal at idle just at startup.

Here is what has been replaced:

Alternator/ duralast gold from autozone
Belt tensioner/o reily
Belt/ 2 years old from autozone
Water pump/ autozone
power steering pump/o reily

Belt dressing does not help at all, the squeal stays the same after it is sprayed on. I have talked to many mechanics about this. They have mixed opinions ranging from a new belt, ac compressor, or the alternator.

Any help is greatly appreciated. This noise is driving me insane.

 

[2000StreetRod]

when did it start?

So your belt is slipping at engine start or when the alternator is under load.

Was the squeal present before replacing the alternator?

Does the replacement alternator have the same diameter pulley as the old alternator? Is it a 130 amp alternator?

Did you replace the entire serpentine belt tensioner or just its pulley?

Is the replacement serpentine belt the same length as the stock belt?

Has your crankshaft balancer failed?

 

[my98nnj]

Look at the tensioner, there are marks on it that line up with an indicator. Make sure the indicator is midway between the marks, if that's ok you have the right size belt.
Next remove the belt and by hand turn each accessory pully. They should spin freely. If any are tight or rough, that item may need to be replaced.
Last, the belt itself could be at fault. I went through 3 Goodyear belts in one year before I switched brands and got one that didn't sound like a mouse chirping.
Consider a motorcraft belt.

 

[schaffnerb]

Street rod,

Thanks for your questions
1. The belt squeals both at start and under load. Much worse under load.
2. Yes the squeal was present before the alt.
3. The new alt is 130 amp with the same size pulley.
4. Replaced entire tensioner.
5.Belt length is identical.
6.I do not believe the crankshaft pulley has failed.

I am leaning towards the ac compressor. Here is why

at idle with the ac or defrost on it will squeal ( lights on too). once the ac or defrost is turned off the squeal goes away.

the squeal comes from the alt. the gauge drops way down.

I think the compressor is drawing too much power at idle for the alt to keep up.
The compressor pulley however spins very free by hand and there is no play to the pulley.

Regardless I think I will replace the ac compressor since there is 175,000 on the explorer.

Thanks so much for your response!

 

[2000StreetRod]

A/C compressor electric clutch?

Have you added excess refrigerant to your system? Is the high pressure excessive? The compressor could be difficult to rotate. The A/C compressor electric clutch could be drawing excessive current (trying to rotate the compressor) and overloading the alternator but I suggest further testing before replacement. There's a connector at the front lower left of the A/C compressor that if disconnected will disable the A/C compressor. Mine is a pain to disconnect but it might be worth checking. If the clutch is overloading the alternator then with the clutch disabled there should not be any engine start belt slip if your battery is fully charged. You might have your A/C pressures (high and low) checked before replacing the compressor. However, the high pressure cut off switch should prevent excessive pressure. The A/C compressor bearings may have failed.

 

[schaffnerb]

Street rod,

Thanks for the advice. I have never needed to add refrigerant as it always blows cold. I will disconnect that connector you speak of and see if that eliminates the start up squeal.


thanks.

 

[koda2000]

humm, on my 2000 (V8) the electrical plug/connector for the compressor clutch is right on top (at the 12:00) position. easy to unplug. but if you set your HVAC control to VENT or FLOOR the compressor should never come on.

 

[bandit11]

check for residual build up of burnt rubber in the vee grooves of the pulleys, remove with a wire brush if present, also check that the belt is routed correctly, it is possible to fit the belt incorrectly, the routing diagram is on a sticker under the bonnet or in the owners manual.

 

[2000StreetRod]

not the clutch solenoid

I checked the wiring diagrams and the A/C relay that controls the A/C compressor clutch solenoid receives power from a 10 amp fuse (Fuse 1 in the battery junction box). So the maximum the solenoid can draw is 10 amps which your alternator should be able to handle with no problem.

I suspect something is causing slack in the serpentine belt at the alternator allowing the pulley to slip and reducing the output. Or, the alternator is binding causing the belt to slip and the output to drop.

 

[2000StreetRod]

check the balancer

Your harmonic balancer should look like the one in the photo below.

This one has failed and the belt was running on the inner section.