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Fan belts walking off pulley of 1962 390

Started by Matt Innocenzi, May 23, 2016, 12:02:03 AM

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Matt Innocenzi

Hello all, for the past year, I have had a vibration problem in my 1962 Fleetwood 390.  It seems the vibration only comes between about 1500-2500 rpm.  At idle, she is smooth and quiet.  The steering has always felt a little choppy as well, like it will be tough at first, and then give way to a smoother turn.

Thinking the vibration may have been from the carrier bearing in the driveshaft, I replaced the carrier bearing and driveshaft with a spare one.  No change. 

Driving today on the highway, I felt a "pop" in the steering wheel.  Suddenly, the vibration went away and it never ran smoother.  At the same time, I noticed I had no power steering the and temp gage was climbing.  Luckily I was not far from home and when I finally got her home, all three fan belts (Generator, A/C, and P/S) were hanging on the fan pulley and walked off of the vibration damper.  I had no generator, A/C, water pump, or P/S but it ran beautifully and you could have balanced a pyramid of Champagne glasses on the hood at 55 mph it was so smooth.

All of my pulleys are aligned, so what would cause every one of them to come off the grooves?  And how is this related to the vibration I feel?  I am suspect of the P/S pump because of the choppy steering, but could a malfunctioning pump cause the vibration and derail all three belts? 

Could it be the harmonic balancer?

Very strange condition that I have never seen or heard before.  Ideas welcome!  Thank you!
Matt I
CLC #21633
1958 Cadillac Sedan DeVille
1962 Cadillac Fleetwood

Bobby B

Matt,
Hi...I've never come across anything like this before. I can't wait to see what the outcome is. All 3 Belts at ONCE???  WOAH!  :o I can only believe that it has something to do with your Pulley on the Harmonic Balancer.  If you're sure it's not "Walking" at a certain RPM and everything's tightened up down below as far as the crank/ bottom end goes, the most simple and logical explanation is that when one of the belts let go, it somehow crossed the other belts while still on the pulley, forcing them to jump off. Kinda like a wedge across the Damper. At that speed, things can happen real fast. The vibration was probably a warning sign of something waiting to happen, and it finally did. One of your Accessories most likely seized causing this to happen. Check to see which one is the culprit. Keep us posted......
                                                                                                                                 Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

Glen

When I bought my 68 ELDO (in 1973) it had a replacement engine.  What I did not know was the replacement was a 69 engine.  I learned that when I put a new set of belts on all bought for a 68 engine.  I had several incidents where the belts were thrown off the pulleys. 

After some investigation I discovered the difference and bought a set of belts for a 69 engine.  I have never had any more problems with the belts. 
The differences in the belts were the width.  15/32” for the 68 and 3/8” for the 69. 
You might want to check that on your car. 
Glen Houlton CLC #727 
CLCMRC benefactor #104

Matt Innocenzi

Bobby, yes, it was pretty incredible.  The P/S belt was thrown to the back and the A/C and Generator belts were thrown to the front.  All of the accessories are fine and spin freely.

I have been thinking about this all night.  What I did not mention was an incident back in September where, instead of throwing the belts off, the harmonic balancer actually walked off the end of the crankshaft.  By some miracle, I heard the harmonic balancer bolt come off, and seconds thereafter lost my steering and generator, pulling over.  I found the bolt and the balancer was at the end of the crank about to come off before catching it in time.  Without thinking of the belts, I simply put lock-tite on the end of the bolt and tightened the *$@% out of it to the crankshaft.  My guess now is that instead of walking the dampener off the crank, it is walking the belts off the pulleys.

Glen, you make an excellent suggestion.  I have the original engine, but when I bought the belts, I just accepted what the parts store gave me without even thinking about the width.  Does anyone know the correct width or part number for 1962 fan belts?  I did notice that trying to get these belts on the car is particularly difficult, most because of the clearance between the cross member and the harmonic balancer.  I thought the problem was more of the belts being too deep, but I can see how width can screw them up as well.

I think we are on to something... 
Matt I
CLC #21633
1958 Cadillac Sedan DeVille
1962 Cadillac Fleetwood

Jeff Rosansky CLC #28373

The balancer sure sounds like the smoking gun.
If that doesnt turn out to be it, check your water pump bearing. When I changed mine a vibration went away. If that bearing is bad it would loosen the belt and this could happen. Before you put it back together, I suggest you check water pump bearing play.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Scot Minesinger

Probably one belt was the problem and when it came loose it forced the others off.  To diagnose, install one belt at a time, run the car and see if the vibration returns.  Then you can determine which one it was.  Likely one belt is the problem.  Normally I see this on power steering pump being bad or fan clutch.  In shop manuals often it goes thru step by step procedure on curing this type of vibration by removing each belt and seeing if problem goes away.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

fishnjim

Definitely check the pulley alignment.  Take a straight edge and match with the outer/inner most pulleys.   The other thing is the size/proper belts.   Sometimes, they substitute generic belts based on length and need to be quality and correct width and groove angle.
The vibration however, is not normal.   It could be the harmonic balancer, they have rubber inside which goes bad.   It's behind the crank pulleys.   You can observe the motor running, quickly with no belts, and look for wobbles.
If the water pump vibrates that bad, it'd be spilling coolant.
It could be the PS, A/C, or generator bearings also.   Check for play.
The A/C clutches are also notorious if it locks up, it'll throw belts.
It's not uncommon, if one goes, off they all go, but sounds like they were loose to begin with.   The broken/loose one gets under the others and they come off.   So check which one broke free for another clue.  If it's intact and was just loose, it'll have marks from the pinching.