Squealing going uphill

[cci]

I've had a '70 C/20 (350) for a few months and overall it runs like a top. Recently I've noticed a squealing noise - similar to a slipping belt - when I am on the gas going uphill.

I live in a higher altitude area, and descend about 500' or so heading into town. On that leg of the trip the truck sounds normal. On my return trip though, I can hear the squealing pretty loudly as I'm climbing back up. If I let off the gas, the squealing stops - but of course then I lose speed.

The belts (my first guess) look perfectly fine and are good and tight. The previous owner had the fan clutch replaced, so it looks all nice shiny sitting there. Of course I realize that shiny doesn't equal working properly.

I just don't understand the relationship between the noise and going uphill.

Thanks!

[truckdude239]

The belts slipping under load
Posted via Mobile Device

[cci]

Originally Posted by truckdude239

The belts slipping under load
Posted via Mobile Device

That was my initial guess, but they seem pretty tight and not "glazed". I'll try tightening a bit more or maybe a new belt.

[GASoline71]

I'm pretty much 100% sure it's the belt as well. Nothing else under the hood will "squeal" under load. A power steering pump going bad or alternator bearing going out will "whine", and a wicked vacuum leak will "whistle".

Gary

[cdowns]

power steering belts need to b alot tighter than other belts

[cci]

Thanks gentlemen. I guess the simplest answer is probably it.

[68gmsee]

So, did tightning help the squealing?

I was also going to say belts but you can usually simulate that by revving the engine up. Since you didn't say you could duplicate it, my guess was something in the torque converter? Just a guess though.

[TBONE1964]

Here is how you can diagnose if you have a belt squeal. Take the belts off and drive up the same hill. If there is no squeal, then you have diagnosed your problem. I am sure that it would not be such a distance as to create an over heating issue or charging issue, correct?

Now for the very strange side to my story. I have a friend here in Mich with a 350 Chevy powered jeep. At times going up a steep hill (like in the sand dunes) we could here a noise like a belt squeal. Same thing, removed the belts but the squeal continued. Long story short. The engine had enough crank shaft end play to allow the crank to move and the front crank seal would make contact on a different area of the crank and squeal. You want to talk about a head scratcher.

Process of elimination is a good tool in this case.

[PanelDeland]

You may want to change the belt.Many tighten a V-belt putting more strain on the bearings of components.It will usually work for a while but if you inspect the belt and it's in the bottom of the groove,it needs replacement. A V-belt transfers torque in the area between the slash and v like this \V/.The pressure of the v being pulled into the groove is where the torque transfer takes place.If the belt bottoms,it cannot be pulled into the V enough to transfer that torque well.Hope this helps you understand so you have more info.

[72chevyk10]

if you have a edelbrock (maybe other carbs?) mine squeals going uphill when the secondarys are partialy open. but if i go WOT it quiets down to just normal engine noise. to me that eliminates the belts, on my truck...

[cci]

Originally Posted by 68gmsee

So, did tightning help the squealing?

I'll know tomorrow. Upon closer inspection, it appears that 'yes' the belts are tight. However, as I went to further snug-up the alternator belt, I discovered that the threads in the alternator mounting "ear" are almost-but-not-quite stripped. I'm sure the previous owner knew this, but he lived in a lower-altitude area and may have never experienced the issue. I'm guessing that this allowed the alternator to move the tiniest bit - just enough for the belt to slip.

Anyway, I'll fix it tomorrow and I'm betting that will be the end of it.

Thanks to all who replied.

[JointTech]

my tranny squealed like a banshee when it slipped going from second to third.

[ItsRandy]

Mine squeals when I step on the gas...but then my tires smoke. Same problem?

[ajsfirehawk]

I just picked up a C/20 a little over 8 weeks ago and I too had a squeal, but only during acceleration. I was drivetrain speed and when I coasted or eased off the accelerator it went away. I began to suspect u-joints, I don't have a press so I took it to my mechanic. New front u-joint, sound gone. It sounded a lot like a squealing belt.