1986 F150 with a 4.9L converted to an offy with 390 Holley and DUI ignition
My alternator is squealing like crazy. I have replaced the alt, and the belts.The pulley could be better but I have never had this problem before.
Now, this is where it gets odd. When I start the truck the alternator squeals, but when I shut the truck down it does not (tapped into something to that keeps my ignition on for 10 seconds)

This the squeal

This is when the squeal stops. It seems the squeal goes away when the alt is not excited. Also, no squeal when I remove the plugs from the alt so that is it in a freewheel state.

 

We assume the belt has the proper tension.
What belt are you using? Gates belts seem to be notorious for squealing.
And if the Alt pulley is worn this can cause it as the sheave won't be making full contact on the belt and it'll limit the torque it is capable of handling before slippage occurs.

So a couple things to explore.

 

How old is the battery?

 

I'm not sure I follow what you mean about stopping the engine. Nothing turning and thus no squeal seems perfectly normal to me. What did I miss? Where did I leave my mind-reading pills? And what do you mean about "tapped into something to that keeps my ignition on for 10 seconds"? I'm scratching my head on that one.



That sounds normal to me. Less load on the alternator means less load on the belt. Once again, did I miss something?

What's with the tach in the second video? Is it dead?

On a possibly unrelated note, you may want to replace that emergency battery terminal as seen in the first video. I've fixed many no-start/slow-start faults by either installing a crimp-on terminal or replacing the entire cable. This could be possibly related to the squeal if the charging current is restricted on the way to the battery, so the regulator is commanding maximum output all the time:

 

You have your belts set up differently than my 85 f150 4.9 non airconditioning. It looks like you have them setup wrong...

Mine has dual belts on the alternator, water pump and crank. The power steering pump attached only to the crank pulley on the front most spot.

Perhaps that along with:
1. Loose belt
2. Crooked pulley
3. One belt driving the water pump and alternator...

Could be causing slippage.

Make sure they are lined up straight with each other, Tighten them, reroute them to how I mentioned above with dual belts on the alternator... in that order.

Let us know how it goes
Jason

 

Also I forgot to add that the pulley on the alt gets incredibly hot.

Jason,

Mine had AC but I took most everything out for it and that is how the belts were set up.
So you have a belt that is crank, water pump, alt.
a belt from the water pump to the alt.
A belt from crank to PS

KR98664,

So the wiring was jacked when I got the truck. I pulled out the most of the emissions and the stock intake and carb. To run the ignition I pulled from the bat with a fused wire to a relay. To trip the relay I poked around the wiring till I found a hot with the ignition in the accessory/on position. The wire I tapped into holds a charge for about 10-15 seconds after I turn the ignition switch off.
Tach is dead

Franklin2
The bat that is in the video is old but I had just changed to that one from a 2 day old battery.

 

A slipping belt will get the pulley hot.


Did this start after you pulled everything off?
If you have 2 belts going around the ALT but NOT THE SAME equipment the belts could be going at 2 different speeds. 1 has to give/slip and you will get the noise.
Dave ----

 

Dave,
No everything worked fine, I know everyone says that. The truck sat for about 3 months as I sorted out the exhaust. Got the exhaust sorted and fired the truck and the squeal appeared.
"So you have a belt that is crank, water pump, alt.
a belt from the water pump to the alt."

I was just asking jason how he had his set up. I have just 2 belts. 1.) Crank, WP, Alt 2.) crank, WP, PS The third groove is empty, former AC belt)

 

Most likely the pulley is glazed and that in turn glazes the belt. Is the FEAD stock or has it been modified in some way? Does the drive and driven pulley align?

When you shut the engine, the ALT circuit is closed. No ALT drag.

Use a water spritzer bottle and hit the ALT pulley while running.

 

There is always the old stand by...belt dressing spray. It may recondition the belt and stop the slippage.

 

Can you even get belt dressing any more?
Dave ----

 

...belt dressing ...

Yeah, you can still buy it. It's in the same WallyWorld aisle with cans of compression and steering wheel suicide *****.

 

here is my setup.

 

To the uneducated and ill informed it may seem like another one of those snake oil items but it is far from it.
Belt dressings are used on industrial belt drives and conveyor systems to help stop belt squeal and prolong the life of the belts and sheaves it is used all the time in those applications.
So don't be so quick to write it off as a possible solution just you are not aware what it actually does or is for.

 

I know what it is and have used it on autos, with out much luck, but lever on industrial belt drives & sheaves.
If it started to squeal tighten it up or replace the belts and yes belts some up to 5 belts.
Thing was you had to get a matched set or better yet a belt mat with the number of belts needed for then AHU/fan.


We also went to cogged belts & drives to cut down on slippage as it was wasted energy. Some of the bigger AHU had variable speed drives to cut back the RPM of the motor/fan to save energy.
This was in a hospital.
Dave ----