Squealing from engine bay

[howdisrespectful]

Hi everyone!

this morning my ‘91 4.0 XLT began squealing from the engine bay. This is completely new.
it was a constant squeal coming from what sounded like the steering pump, but I’m not sure what it could be.
After driving for a few miles the squeak died down some and only made noise once I hit ~1,200 RPM.

I could upload a video if that's allowed.

Has anyone else experienced this? The belt was replaced about 1.5 years ago.

are there any tips on diagnosing where the squeal is coming from/what could be causing it?
Thanks!

 

[Ranger850]

I know you said the belt is fairly new, butI'd still check it for tiny cracks. A dry rotted belt will let you know it needs to be replaced. IF that checks out, your Idler pulley could be going bad? Remove the belt and give the idler a spin, if it spins smoothly with no wobble, move on to another pulley. So on and So forth until you find the bad pulley/bearing.

 

[howdisrespectful]

Thank you for the response! I will check each pulley tonight.

Also thought I should add:
The squeal doesn’t change when driving or turning the car. It’s directly related to RPMs, increased at speed and decreasing at braking. Pitch and frequency are unaffected by any other movement.

I found a small amount of power steering fluid on the PS pump cap so I checked fluid levels but it’s all good.
I’ll update once I get the belt off tonight.

 

[gaz]

@howdisrespectful ,
Could have hit a deep puddle getting water to the belt, making it slip. They sell this belt No-Squeek at the auto parts joints; it can help sometimes. Also Belt Dressing can quiet a noisy belt.

Check your power steering fluid level.

 

[howdisrespectful]

Ok small update:
Removed and inspected my belt and it looks fine. No rot, no cracks or tears.

I inspected all pulleys and the only one that was stiff and squeaked a bit was my power steering. It had a lot of resistance and the pulley itself had “in and out” play. (Best way I can describe is z-axis play. I could push the whole pulley in and out of the power steering pump a bit)

I’m gonna assume that’s my problem. Is it worth it to replace the pulley only? Or should I go ahead and replace the whole power steering pump while I’m at it. The truck is in great shape.

thanks for the tip @Ranger850 !!!

 

[Ranger850]

IDK if a bad PS pulley would indicate a bad PS pump or Not. Hopefully somebody else will chime in on this matter. Check to see if a new pump comes with a pulley. IMO, that would mean that both are to be replaced at the same time, IF they sell just the pulley, that COULD mean that the pulley doesn't last as long as the pump, OR vise versa

IF that makes sence . . .

 

[Uncle Gump]

That steering pump pulley is pressed on the pump shaft. If the pulley moves in and out I would say the pump is shot.

Is the fluid cooked?
Did you start the engine with the belt off to ensure the noise went away? Don't run the engine more then necessary... water pump won't be turning.

With fluid in the pump and reservoir... the pulley will have some resistance. But it shouldn't be "hard" to turn... but it won't free wheel like the other pulleys.

 

[howdisrespectful]

Update!

parts came in and I got to work. Replaced steering pump as well as return and pressure lines. Decided to keep the current pulley as it looked fine.

job was easy enough took me about 2 hrs with a “pulley puller” rented from auto parts store and a quart of some type F ATF.

got everything installed and bled the system. Everything seems good!! I’m surprised at how quiet this new pump is. I didn’t realize quite how loud the old one was. I did use a new edelmann pump and hoses though..

Thank an everyone for all the tips!
Oh one more thing I noticed the new pump has a similar amount of in and out play as my previous one. It must be a feature…