Squealing Belts - and How To Fix Them

[Sharecropper]

I am currently finishing up the front end of my P400 engine, checking the alternators and power steering alignment, and it occurred to me that it might be helpful for some of our junior members to understand why belts squeal and wear out quicker than they should. And then explain what to do to correct the adverse situation and eliminate the squealing, and lengthen belt life in the process.

Assuming belts are in good shape and are tensioned properly, they squeal and suffer premature wear/failure for one reason only - misalignment between 2 pulleys. The squeal happens when the misaligned and rotating belt contacts the inside edge of a pulley, and then must be twisted against that same side to run around the interior circumference of the pulley. This improper and constant contact produces heat and introduces stress to the filaments of the belt, similar to working a piece of wire back and forth between your hands to make the wire break.

To rectify the situation and permanently eliminate the squealing and extend belt life, here's what needs to be done -

First, temporarily remove your fan clutch assembly and re-install the 4 nuts back onto the studs of the water pump pulley; tighten securely, then use a straight edge ( I use my aluminum framing square ) to determine the alignment of the alternator pulleys with the straight edge. Because I am installing rebuilt Wilson 27Si alternators in original CUCV alternator brackets, for whatever reason my alternator pulleys were misaligned rearward just a smidgen more than 3/16". I reached out to Norm at KRC Power in Kennesaw Georgia and obtained a couple of .20 spacers to fit the .670 shaft of the alternators, and installed the spacers between the pulleys and the fans. This effectively moved both alternator pulleys forward precisely the correct amount for perfect alignment. Once I got the 2 alternators aligned with the water pump pulley, I then looked at the power steering pulley. It too was out of alignment rearward approximately the same amount. After thinking about this for a minute or so I figured the P400 timing gear cover, which is 34 years newer than the 6.2 OEM cover, was probably the reason the water pump pulley was positioned forward approximately .20". Interestingly, the CUCV crankshaft pulley, mounted onto the Fluidampr, which is mounted on the P400 crank snub, aligned perfectly with the water pump pulley. Back to the power steering pump pulley - It too needed to be moved forward approximately .20", so I grabbed my "pulley puller" (man that is a tounge twister) and pulled the power steering pulley forward until it aligned with the alternator pulley, water pump pulley, and crankshaft pulley. I checked/pulled/checked the alignement by sliding my straight edge down inside the alternator pulley and down inside the power steering pulley, until the straightedge aligned perfectly into the groove of the crankshaft pulley. Whew! That is a lot to say. Anyway, here are a few photos. There is no doubt in my mind that if you do this and install new Gates belts, your squealing will be over and your belts will last much longer. By the way, there are 2 bolts which must be loosened to adjust the passenger side alternator, 3 bolts for the drivers side alternator, and 4 bolts for the power steering pump. When tightening the belts, remember to tighten the power steering belt first, then the drivers side alternator, and lastly the passenger side alternator. Be careful in prying the power steering pump, as a screwdriver against the thin reservoir wall will puncture it. Lever the bracket, not the pump housing. After everything has been aligned and tightened, remove the 4 nuts from the studs in the water pump pulley and reinstal the fan clutch. Use blue Loktite on the threads.

Hope this helps.

 

[richingalveston]

Very nice write up, I did the same with my new motor. I just had to use some washers behind the power steering pump. everything else worked out fine. I used a small 3ft level since i had the front clip off. One way to get the power steering pump tight without prying is to use a floor jack and a small piece of wood I used a 2x2 piece of wood. The wood goes on the outside edge of the bracket and normally touches the frame rail from under the truck. You just jack it up until the belt is tight. You can get the belt to tight with this method but if you do not have the right extension to use the square hole in the bracket, a piece of wood and floor jack work very well

 

[Sharecropper]

After aligning all pulleys, I installed new Gates belts. #7448 for the power steering, #7575 for the drivers side alternator, and #7483 for the passenger side alternator as specified in the TM and in the SS Wiki. However after installing the belts and tightening them to the correct tension, I realized that both alternators were positioned near the maximum position in the brackets. So I decided to see if shorter belts would work, so that when these belts were worn a little and stretched, there would be more adjustment capacity. I found a website which shows every Gates belt and their respective #'s and lengths http://outdoorpowerinfo.com/belts/gates_belts.asp . I didn't think it was necessary to try a shorter belt for the power steering, so I focused on the 2 alternator belts. The chart shows that #7575 for the drivers side alternator is 58.13 inches long, so I ordered a #7570 which is 57.63 inches long. For the passenger side alternator, the chart shows that #7483 is 48.88 inches long, so I ordered the next size shorter #7480 which is 48.63 inches long. The belts came in and here are my results -

For the drivers side alternator, the shorter #7570 belt would not go on. With the adjustment screw completely removed and the alternator moved inward as far as it would go, it just could not be installed around all four pulleys (crank, water pump, PS pump, and drivers alternator). I probably could have stretched it around a pulley with a long screwdriver and made it work, but this would have defeated the purpose. So I re-installed the recommended #7575 and tensioned it correctly. A spare #7575 will stay with the truck from now on.

For the passenger side alternator, the shorter #7480 slipped around the pulleys perfectly and when the alternator was tensioned and tightened, the adjustment screw located itself approximately halfway in the adjustment slot. So from now on, I will keep a spare #7480 with the truck.

I want to re-emphasize the importance of aligning the pulleys. As well as the proper sequence of tensioning the belts. The very first belt which should be aligned and tensioned is the drivers side alternator belt. The pulley on the drivers side alternator must be aligned before the power steering pully can be aligned. The drivers side alternator and power steering pulleys should be aligned first, without any influence from the passenger side alternator belt. After the drivers side is complete, then align the passenger side alternator. Remember that there are 2 nuts which must be loosened to adjust the passenger side alternator, 3 nuts on the drivers side alternator, and 4 nuts on the power steering pump. There is no doubt in my mind that is the power steering pulley and the 2 alternator pulleys are properly aligned and tensioned, the belts will run cool and last much longer and provide a long service life.

If your belts are squealing, the pulleys need alignement.

Hope this helps.

 

[cucvrus]

I really like your solid pullies also. That is what I always run. They will help with belt wear also. The stamped pullies get hot faster and then the rust and pit after sitting. The rust and pits like to chew up the rubber belts. If a belt makes one squeal it needs attention. I am not afraid to use a socket to turn the alternator pulley to get a tight fitting belt on. It has worked for me for years. few have the exact same fitting belts. I choose the parking lot belt changing. The tighter the belt on the initial installation the better for me. I don't mean cranked down tight. I mean the most useable adjustment when installed and new. I agree the listed belts are at the end of adjustment. Some may argue it is the solid pullies. So be it. Thank you for your post. I still love new vehicles with serpentine belts. That by far is the best set up. I didn't think so 30 years ago. But I am sold on them now. I have replaced a tensioner or 2. But never had the issues that come along with the V belts. Good Post. Have a Great Day and Be Safe.