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Discussion Starter #1
Hi,

Here's a way to test for a noisy serpentine belt vs noisy bearings:

Put some water in a pump spray bottle and set the sprayer to a "stream"; like a squirt gun (not a misted spray). With the engine running and the you're hearing the squealing, spray a little water on the belt contact surface of any metal V-grooved pulley you can easily squirt at. If the noise goes away, you know it's a noisy serpentine belt. The water acts a temporary lubricant to kill the noise before it evaporates. Belt squeal may be due to misaligned A/C pump, alternator, power steering pump, etc. (read on).

As you are probably aware, a cold belt squeals more, so do the test when the engine is not already hot.

In my case, not one, but two remanufactured water pumps had the water pump pulley flange pressed on too far down on the pump shaft. I finally fixed the squealing problem by putting 4 washers underneath the pump pulley before bolting it back onto the pump flange. That set the pulley back out where it was better on the vertical plane with the rest of the pulleys and rollers. Not pretty, but it works: no more squeal.

Fyi - Doing the pump job twice was not the only blood let: Before I was finally enlightened about the "water spray" test (from a seasoned auto electric acquaintance), I replaced both of the serpentine belt idle rollers (~$50). I then replaced the serpentine belt with one of the new quiet Dayco "Poly Rib" belts that are supposed to help quite noise on older cars like my '93 Taurus (68,000 miles). The Poly Rib belt (~$30) has flattened ribs instead of pointy ribs). It made less noise than the older style "Poly Cog" belt, but there was still some noise: no fault of the belt.

I finally determined it was a problem with the water pump pulley alignment when I put the new Poly Rib belt on. I could see (and hear) that it was trying to "walk off" the end of the pulley. The Poly Cog belt (almost new) stayed put, down in the pump pulley grooves, and gave no clue where the problem was. I kept the Poly Rib belt is on there and it is working just fine.

If you're thinking about getting one of Dayco's new "Poly Rib" belts, you have to ask your supplier to actually look at the belt they have in stock, or order one from the factory for you. Unfortunately, Dayco's part numbers are the same. They have a sparkle to them also; like they have graphite or something embedded in the rubber.

Live and learn . . .
Brcobrem
 

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Discussion Starter #2
Hi TCCA,

It's been several months and the belt squeal came back for the first couple miles of driving. Back in 12/08, I thought I had bad remanufactured water pumps and fixed the squeal by shimming the water pump pulley out a little bit. This time around I could see what the real problem was.

I removed the water tanks and now I could see that belt tension arm pulley sticking (slightly askew) about about 1/8" more than any of the other pulleys. This was a slight mystery because I had already replaced the pulley on that arm. So I removed the tension arm and put it upon the bench. Measuring from the bench surface to one side of the pulley, and then the other side of the pulley was about 1/8" difference. I'm thinking that perhaps the arm had been bent. Looking back, the squealing had started shortly after having a garage replace the AC compressor and perhaps they had bent it somehow.

Looking further at the backplate of the arm (ie. engine side), I noticed that the backplate was not parallel with the arm itself. Now I realized that the arm was a two piece assembly. So what had happened is that the nylon assembly inside the arm (that holds the spring) had either worn out or was damaged. This caused the arm to move out of its parallel positioning with the engine when it came under tension.

I ordered a new arm assembly. The instructions specifically mention "When rotating the tensioner to the belt installation position, do not force tensioner beyond the stops!". That said, I suppose it is possible to break the insides of the tensioner.

So I installed the new tension arm assembly (with the a pulley already attached), removed the four washers from under the water pump pulley, and started it up: no belt noise whatsoever and the belt is turning very smoothly.

For what that's worth . . .

Regards
Brcobrem
 
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