2000 xlt - I have replaced the cam synch,cam sensor,throw out bearing,slave cyl,and ran the motor WITH and WITHOUT the belt on. We just tore it completely down and replaced all seals and bearings, and pulled the IAC while running and I have an unrelenting noise. Its a constant bwoop,bwoop,bwoop about every 2 seconds. Rpms dont change the speed or sound of it. Drove it home tonite and it runs like a top, plenty of power, same mileage but OMG the sound is embarrassing and loud. 3500 rpms or idle, same sound and same repetition. It will relent for a second or two if I stand on the gas, but then it's right back to bwoop, bwoop, bwoop.

When I plugged in the OBDII scanner it said nothing's wrong, truck's perfect! Run it! If only the scanner had ears. I would really appreciate any suggestions. Thanks!

 

what engine?

 

3.0 V6. That info is somewhat important

 

Does it make the sound when you are idling in neutral? If so, that would rule out everything but engine/transmission. Does it make the sound whether the clutch is in or out?

 

i think you need to get out the the 2 foot heater hose or the engine stethoscope and try and get a better idea of where the noise is coming from...

 

Yes, the sound is the same whether or not the truck is in gear or in neutral, if the clutch is in or not, if I'm driving 10 mph or 70 mph. Does it while idling, does while revved and sometimes it goes away... but it always returns.

I've put the stethoscope to it and it comes from the rear of the engine and the cam synch area. I think it comes out of the bell housing but since I've replaced just about everything down there I'm not sure what it could be. Also, it did it with the transmission off.


It is a major puzzle and I'm convinced it has to be something like a 2 dollar part gone bad. I hope anyway...

 

Did you do all that work looking for the noise?

Once every two seconds regardless of RPMs might not be in the engine. I'm thinking vacuum canister or something vacuum related since it goes away with WOT for a few seconds until vacuum builds. Any vacuum servos/motors that could be coming on and off like that?