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Loud Squeal on Acceleration

Dabba

Dabba

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Long Island, New York
I know it could be anything but I can tell you it's related to the engine rpms, not speed. There is a slight smell of burning rubber, it's cold as hell out, and in my m1008 cucv, the gen2 light has always come on faintly, but now it will come on occasionally, indicating the pass side alt is disengaging. I'm thinking the clutch in the alt is going. Does this sound consistent? I don't remember the last time it's had a rebuild, so maybe it's time?

I'm really hoping it's this and not something more complex and expensive.
 
Something belt driven.
I had the A/C Compressor on my 94 F250 lock up, and it smoked and squealed like a pig until it threw the belt.
 
Dabba said:
I know it could be anything but I can tell you it's related to the engine rpms, not speed. There is a slight smell of burning rubber, it's cold as hell out, and in my m1008 cucv, the gen2 light has always come on faintly, but now it will come on occasionally, indicating the pass side alt is disengaging. I'm thinking the clutch in the alt is going. Does this sound consistent? I don't remember the last time it's had a rebuild, so maybe it's time?

I'm really hoping it's this and not something more complex and expensive.
Click to expand...
My civvy truck was doing this - it was the alternator bushings on the verge of seizing. Replaced the alternator and good to go...
 
My truck does the same thing, but only when the motor is cold, it quits when it warms up, mine is the power steering pump, somehow it keeps getting air in the system which is why it squeals.
 
I had the same thing when cold. Turned out the belt was slipping on the Power Steering pump's pulley. A month or two later the power steering pump started leaking and went bad.
 
Whelp, I'm going to have to wait until my girlfriend comes over so she can hit the gas and I can look/listen under the hood at the same. It doesnt happen all the time so I may not spot it. I'm still really hoping it's the alt
 
I'd also say it's either the belt on the alt. or the bearings on the alt. I'd take the belt off and check for cracks or signs that it's worn out. And while it's off spin the alt. by hand to see if it spins fairly easily or if the bearings make noise.
 
Dabba said:
I know it could be anything but I can tell you it's related to the engine rpms, not speed. There is a slight smell of burning rubber, it's cold as hell out, and in my m1008 cucv, the gen2 light has always come on faintly, but now it will come on occasionally, indicating the pass side alt is disengaging. I'm thinking the clutch in the alt is going. Does this sound consistent? I don't remember the last time it's had a rebuild, so maybe it's time?

I'm really hoping it's this and not something more complex and expensive.
Click to expand...

mine did the same thing a few weeks ago..
tensioner was completely locked up.
a few weeks later the alternator was pretty well locked up.
 
How hard is a tensioner to replace? Actually I'm not sure I have them on the cucvs dual alt belt system. I need to look.

I love how winter makes all the weird noises come out. On startup I get a really loud hum that sounds like it's coming from the bottom of the firewall. Stepping on the brakes makes it much worse. It's rom dependant but goes away as she's warmed up.

Don't think it's related. Sounds are different and the squeal happens while warm. I'm guessing the power brakes don't like the cold.
 
Dabba said:
How hard is a tensioner to replace? Actually I'm not sure I have them on the cucvs dual alt belt system. I need to look.

I love how winter makes all the weird noises come out. On startup I get a really loud hum that sounds like it's coming from the bottom of the firewall. Stepping on the brakes makes it much worse. It's rom dependant but goes away as she's warmed up.

Don't think it's related. Sounds are different and the squeal happens while warm. I'm guessing the power brakes don't like the cold.
Click to expand...

On my 350 it was cake. Take off the belt, one bolt for tensioner. Reverse for installation. Not sure on diesel models.
 
Dabba said:
I know it could be anything but I can tell you it's related to the engine rpms, not speed. There is a slight smell of burning rubber, it's cold as hell out, and in my m1008 cucv, the gen2 light has always come on faintly, but now it will come on occasionally, indicating the pass side alt is disengaging. I'm thinking the clutch in the alt is going. Does this sound consistent? I don't remember the last time it's had a rebuild, so maybe it's time?

I'm really hoping it's this and not something more complex and expensive.
Click to expand...

You're just doing burnouts. Wait, no, you said it's an m1008 - never mind. I've never seen a clutch on an alternator :confused:

First things first. How tight is the belt? Is it V-belt or serpentine? It's possible you're 5 minutes and $0 from everything working fine.
 
yup, a can of WD40 will find this in 1 minute.. wait for a squeal, just squirt a little shot on the belt, and the belt only, if the noise changes, or goes away, it's the belt either too loose or needs replacing... a 1/2" deflection on the middle of the belt is what you want... if you haven't inspected a v-belt in a long time, I'd bet the farm it's looser than that.. alt put's a heavy load on, belt slips...

if that does nothing, than take the WD to the alternator, spray it right in where the bearings are, see if it changes sound..

I'm assuming this is a 6.2 with V's.... tensioner pulley is always a good guess (they go ALL the time) but I'm pretty sure you don't have one as they are generally only a serp set up deal...
 
Thanks guys. I'll try to give my ear a workout and do the wd trick with the help of my girl. It could be the belt, finding the proper size for the cucv is a pain, but its not a lose belt, it's definitely more metal sounding so think it's bearings on something.

I'm not sure if clutch is the right term for the alternator. I know when I first start the truck the alts arent enaged, and once you rev the engine they engage and begin charging. Right now my passenger side alt sometimes disengages when stopping, and stops charging until I rev the engine back up again on acceleration. I'm guessing theres some sort of clutch there wth bearings that might be going bad, may be related. I'll report back later
 
Sounds like a self actuating alternator. There is no clutch, they just don't start producing electricity until they reach a certain RPM.
Most of the time its a one wire alt. When I converted my 1948 8N to 12 volts, I put on a one wire.
It would not charge until I revved the engine almost all the way open. But most of the time, once they start charging, they keep on all the way back down to idle.

If its not a one wire, then the voltage regulator may be on the way out, or the brushes in the alt are worn.
 
That could still point to the belt. If the alt isn't charging, then they don't put much load on the belt. Then when the load does up the belt would squeal. The burning rubber smell suggests that a belt IS slipping. Either it's just loose or worn (easy fix) or a bearing is seizing and forcing the belt to slip. It would be great if you could rev it in Park while watching to see what turns and what doesn't, and how much the belt is flapping.
 
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