fan belt squeels when I hit 70mph??

I cant figure out why, but when i hit 70 mph the fan belt starts squeeling!!! I've tightened the belt, loosened the belt, sprayed belt dressing on it and nothing seems to work. I am enjoying the good gas milage but i just cant drive at 70 anymore!!!

 

Its a speed warning device. Keeps the law off your back. John

 

Are you running a stock type fan, solid drive? Maybe the fan is stalling. Just a thought.

Craig

 

Yea its the stock fan for the motor, pontiac 400, and it's only revvin about 2900rpm at 70

 

Are you using a fan clutch?

Craig

 

nope, just a plain ordinary fan

 

Maybe it's not the belt.
Check generator/alternator and water pump bearings.

Also check the oil pressure as the RPM comes up.
Oil could be collecting in the top end and starving an engine, especially if it's mounted in the car at an angle different from what it was designed for, usually angled down toward the sump some.

 

My guess is the fan blades are to stiff and the pitch is too aggressive for the belt not to slip. If the original application used a fan clutch, this is likely the case. If you want to be sure before you change parts unnecessarily. Start with a cold engine, take off the fan, put the bolts back in to hold the water pump pulley. Make a quick blast to 70 and see what happens. If the noise goes away, install a fan clutch or a flex fan. A fan clutch will free wheel at freeway speed when there is enough air flow through the radiator from the road speed to cool the engine. A flex fans blades will flatten out at higher RPMs to achieve the same thing.

Craig

 

If the belt is tight Id suspect a bearing going bad (Alt, W.P., ect)

 

changed the alternator, and that didnt make a difference, and it runs about 50psi oil pressure, and the motor is sitting level, i have not checked the water pump bearings, and i do not know how old the water pump is ( motor was already in the car when i picked it up ). there is no power steering, and only one belt, i also havent changed the belt, but it looks to be in good shape with no cracks or tears

 

Is it tight? Is it straight on the pulleys?

 

it has about a 1/4" play, i've loosedened it off and tightened it right up and it makes no difference, and yea it is straight

 

Try replacing it. I have a problem with my Caminos belt every so often. It will squeal like a stuck pig right off idle. The belt looks ok but no amount of tightening will make it go away. It looks like it wears the sides of the belt down to the point where it doesnt make good contact. If you have another belt sitting around compare the width and see if the one on the car looks thinner.

 

cool, i'll try that in the moring, and i'll also try taking the fan off and seeing if that helps

 

Try one of the Goodyear gatorback belts, I never have any sqealing problems with those even when reving the motor in neutral.

 

It must be one of those triple digit belts....increase speed until the squeal goes away.....

 

the belt and pulleys are glazed. once the belt gets a "shine" it will slip, try a new belt and clean off the pulleys with lacquer thinner.

 

Belt dressing is the worst shit to spray on a belt. That crap should be banned. All it ever does is cause more shit to collect in the pulley grooves.I have a hunch its not the belt but perhaps an airflow whistle.....

 

More than likely the belt is riding down into the bottom of the Vee portion of the groove. They are designed to not touch the bottom and ride on the sides of the belt along the Vee of the pulley.

 

maybe its getting sceered.

 

If I had a belt squeeling on me at 70 mph id kick its god dam ass and go buy the 105 mph belt.
Dave