Help! Engine Squeal - 1993 Mark VIII

[wildrage]

1993 Mark VIII w/ 120k on the clock, bought 1 month ago

Some a-hole in a BMW SUV was riding my butt last night, so at the next red light I went to WOT to smoke him...wish I hadnt. My mark instantly developed a bad squeal - sounds like a bad serpentine belt. The next morning I crossed my fingers and took the belt off. When I ran the engine (briefly) with no belt, I heard the same constant squeal-like sound. The sound appears to be coming from the back of the engine, towards the bottom.

When I drove my car home with the squeal, the engine acted totally normal. There was no knocking, issues with acceleration (of course, I went easy on it), and no warning lights. The noise seems to be the loudest when idling. When the car is shifted into D it drops. When accelerating the noise gets more high pitched, but less audible, and while coasting (at say 45mph) you almost can't hear it.

Any help would be greatly appreciated...I'm kind of stumped here so throw any ideas you may have at me.

 

[Joeychgo]

Sounds like your belt to me --

 

[wildrage]

I wish it was, but it does this with the serpentine belt COMPLETELY OFF.

 

[Roadboss]

I am going to guess the air injection pump has a leak

 

[wildrage]

Squeal

It would cause that type of squeeling? How do i test it? Thanks.

 

[Roadboss]

This is an electric air pump that injects air into your exhaust manifold to reduce hydro carbons on startup. It normally runs for about a minute or two. It has a vacuum switch, and any of these points may have a leak that possible could produce a noise as you describe, including the pump. If you were to disconnect the solid state relay I believe you could verify if this was your noise source.

 

[wildrage]

Squeal

Thanks, Ill check into it tommorow. Do you think posting a sound file of the noise would help diagnosis?

I really appreciate your help.

 

[Robinson2487]

It might be your tensioner... I had the same problem with my car.

 

[brentalan]

Wouldnt the sound stop with no belt if it were the tensioner?

 

[wildrage]

Yes, it would stop. Thats why I've ruled that out. A wheel cant squeek if it's not moving.

 

[wildrage]

I posted a sound file of the noise on my website. Notice the squeel.

http://www.jamesdelacruz.com/engine.wav

 

[wildrage]

Squeal

I had the car up on ramps today and listened to the sound. I can't be 100% sure but I think that the squeal may be coming directly from the crank pulley, or harmonic balancer. Is there any way to test this? Is it very difficult to swap out? I've been looking on multiple message boards and there isn't a whole lot written about it.

 

[Roadboss]

sounds like an air leak (whistle) to me. Check all vacum lines.