V-belts and then there are V-belts

[DonaldSmith]

I added power steering to my 47 DeSoto, with new 3/8" pulleys to power the pump. The thing would squeal at full turn.  

 

Jerry, who wound up towing me home from the DeSoto Convention and later staying with us for the DreamCruise (stories in another part of this site), noticed that  the pump pulley stopped at full turn, and the squealing was the belt on the pulley.  Possible solutions included reducing the power of the pump, which would involve removing the pressure valve and adding shim washers.  But first we tried tightening the belt as tight as we could.  We did, and the squealing stopped; the engine load increased, the normal occurrence.

 

After Jerry left, and after some driveway maneuvers, the belt began to slip again.  The belt was loose.  Hmmmmm.

 

I discovered that not all 3/8" belts are the same thickness.  I had used 3L series belts, 7/32" thick.  I now installed a 3V series, 5/16" or 10/32" thick.  10 divided by 7, almost one-and-one-half times as thick.  The thinner belt had been wearing out under the load.  I'll try the thicker one.

 

Stay tuned, for a follow-up report.  Here are the two belts:

 

Edited August 18, 2015 by DonaldSmith

[TodFitch]

Don't know how you have your belt setup nor do I know if you still have a water pump with bushings instead of ball or roller bearings. But I know that on my old Plymouth if the belt is tight my water pump bushings wear out very rapidly. This might be a case where your fix for one issue (belt slipping on power steering pump) could lead to another problem (short life on water pump). OTOH, maybe your water pump and/or belt routing is such that it is not an issue on your car.

[DonaldSmith]

My power steering belt only goes between the crank shaft and the power steering pump.  I could add a pulley to the crankshaft, but had no easy way to add a pulley to the water pump.  So I can tighten away.  But thanks for the caution.  It's not a good idea to overtightern V-belts.  Maybe  this fatter belt won't have to be tightened so much as it took to make the thin belt work. 

[DonaldSmith]

Installed the thicker "3V" belt.  No more squeal, for now.  We'll see if that cures the problem of excessive wear and early onset of squealing belt syndrome.  

[james curl]

Everyone understand that a V belt drives from the sides of the v and not the bottom?  That is why the alternator with a narrow pulley needs a wide grove pulley for our old cars, if you use a narrow v belt for the alternator pulley then the bottom of the v belt is all that you have driving the waterpump and fan and it will slip as it is not designed to be used that way.

[Sharps40]

Yes.  V belts work from tension and wedging in the pully (s). 

 

Tension should be the lowest amount that dosn't slip under highest load.  For example, on the water pump, highest tension is usually at start up.  On powersteering, highest load may well be at full lock. 

 

In any event, there should be a slight deflection of the slack leg of the belt at highest load.  If there is no deflection of the slack leg, the belt is too tight and will squeel as will one that is too loose.

 

As for wedging, the belt must be wide enough not to bottom in the pully.

 

Worn out pulleys may also slip/squeel even though the belt is correctly dimensioned and tensioned.  Where possible, replace ancient used pulleys with quality modern pulleys.

 

Toothed v-belts, tighten more as they heat than untoothed v belts, however, adjustment is the same.  If yer not nuts about Concours points, toothed v-belts run better/last longer and though pricier, are a fine reliability upgrade.

Edited August 20, 2015 by Sharps40

[chopt50wgn]

V belts should be flush with the groove in the pulley for proper operation. I have seen some belts that stick up in the pulley or that sit below the top of the groove. And those are not seated correctly and will either squeal or fly off.

[Ulu]

Old "NOS" belts which have shrunken and hardened over the years are usually no good either. I've got a few "brand new" belts which are 30 and 40 years old. Never used, and probably not worth using now.