Hey All,

I recently bought a 2002 Tribute with 3.0 v6 with a little over 200K miles. I’ve put in all new spark plugs, 3 new coils, a new radiator, new serpentine belt and 2 new egr valves after I found the front catalytic converter was plugged. I removed the front catalytic converter and most of the internal contents fell out in small
pieces. I broke up the rest of the pieces thru the o2 ports with a piece of drill rod, so now it’s hollow.

Since I’ve resolved the catalytic converter problem, I’ve experienced a high pitched screeching sound when I accelerate, but immediately stops once I release the throttle.

I originally thought serpentine belt, so I changed it out with no improvement. I’ve got no error codes in OBD2 scan and cannot figure out where it’s coming from. I’ve read several threads on here and check for exhaust leaks, cracked vacuum lines, etc and don’t see any issues.

Has anyone experienced this before and if so, what did you do to fix it?

Thanks in advance for your help!

 

Remove the belt temporarily and retest - def sounds like a serpentine belt slippage.

Same with the water pump drive belt (but only for a couple of minutes to run the test).

 

I pulled the water pump belt first and screeching sound still there during acceleration. Put it back on and removed the serpentine belt and same result.

 

See video below. Hopefully it is more descriptive of what I’m hearing.

 

Brilliant idea to record it!

Unfortunately I can't place it from the noise but I do have a technique that may help you. You need the longest-handle screwdriver you have, VERY carefully place the tip on various places on the engine and listen to the handle (hard plastic handles are best as they carry the sound better), while revving the engine, it should be possible to home in on where the noise is coming from quite easily - its a seriously good technique, ideal if you have several possibilities close together it can help you identify which source is the real one.

That said if it gives the noise with both serpentine and water pump belts off then that rules out every bearing on the engine I can think of, rules out the a/c clutch etc etc...it almost sounds like a waste gate chirp on a turbo engine.

Just to be clear - can you get to a rev range where a constant engine speed and load causes it or is it always a transient noise as in the video during acceleration then it stops?

The only source I can think of is if one of the timing chain tensioners has failed and you are getting a chirp out of the chain but thats a long shot and I hope not the cause...but if the screwdriver stethoscope technique leads you to the timing case you'll know...

 

I bought Tribute 2004 with 300K on speedo a few months ago, had exactly same problem, it was not belt or timing chain noise, it was catalytic converter system, they are 3 parts, left/right exhaust and middle under chassis......I did same as you.....because cost replace 3 of them too expensive ...and the pitched screeching sound was still there when I accelerate reach 4000 on the tacho....I travelled on high ways alot and put over 15K on it without problem....so I don't mind that sound....