Screeching V-Belt


reliable source of info
Had this in another thread, thought it better to move it here:

.... the '58 Chevy truck motor (502)has been eating v-belts (a new hi output alternator seems to put occasional heavy loads on the pulley, and the belt screeches...) and mildly overheating when under a load and in the middle of the day (pulling uphill with a load at noon, hey, I work that truck!), finally decided that the 18 year old BBC water pump was not doing it's job, so am in the middle of a replacement, with is involving cleaning/repainting various front end components I've pulled out (fan, fan shroud, alternator, PS pump, pulleys), and checking out the radiator while I'm in there. So the '55 Sport Coupe project gets delayed a bit longer......

Both of those problems could be from that belt slipping. I don't know what you have for pulleys, but check the v-grooves.
If they are worn and look more like a U instead of a V, then the pulleys are worn and need to be replaced.
If you have unused grooves, maybe you can add a second belt.

Naw, the pulley grooves are ok, they were pretty shiney, took the shine off with some sand paper, but I eventually solved the v-belt wear problem with a different alternator. I had installed a high output alternator, and it was hanging up quite often for reasons I never was able to discover, swapped that out for another alternator, and the problem went away...

That 502 motor has started giving me some indications of slight overheating, on a summer day, temps in the 90's, driving uphill, the temp will creep up to 200, when normally it is very stable at 180. Have changed the water pump, the thermostat, and did a flush of the cooling system, it's better, but still gets warmer than I like on occasion. Changed the fan to a more aggressive flex fan setup, checked the shroud for a good fit, but think it's time for a new, better radiator. The current one is pretty much "stock", and has been in there for 19 years....


The Grumpy Grease Monkey mechanical engineer.
Staff member
belts slip when resistance, required to spin accessories is greater than than the surface friction on the drive belt surface to the crank pulley surface, keep in mind reduced diameter crank pulleys have less surface area and a defective water pump,power steering pump, air conditioning compressor or alternator will substantially increase drag loads on the belt,

some of my least favorite myths

(1) you need to slow the coolant flow thru the radiator to allow time to cool the fluid moving thru it
(2) swapping from a 190F to a 160F T-stat will significantly reduce an engines tendency to over heat.
(3) removing the t-stat will cure over heating


one fact often over looked is that radiator designs vary wildly, and the number of fins per inch of surface area and width of radiator coolant flow tubes can significantly increase or decrease thermal heat transfer efficiency., fin counts vary from 8 to 22 fins per inch on various radiator designs Ive seen.
thus a radiator might measure say 18" tall by 24" wide but depending on design, and fin and tube count, might actually have a radically more or less efficient heat transfer rate.obviously the best and surest way to find out if a radiator, shroud and fan combo cools the engine effectively will be to install and run the component parts you have under the current applications limitations for real world testing and if it needs upgrading your dealing in proven facts vs guessing
ID also point out that all radiators collect crud and become restrictive to flow and much less effective at transferring heat to outside air flow over time, especially if the wrong coolant or water containing excessive mineral content are used so you might want to have yours cleaned out, rebuilt or replaced, if thats needed, after taking it out, an inspection indicates the correct course, a new aluminum radiator, in the largest size quality, radiator, that fits you can afford, is usually a good idea, if it needs replacing



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