Help with Howling Sound

[Rider90]

I need some help diagnosing a sound, of which I brought up in another thread. I've used an automotive stethoscope and pointed it on both idler pulleys (passenger side) and did not hear it. I cannot listen to the idler pulley on the alternator bracket. If it is the idler pulley on the alternator bracket, that would be two in a row. All vacuum lines are connected, and Chuck, no K&N Mod just yet.

Can you guys check it out and throw some ideas if you missed it in the other thread?

http://midwestpanthers.net/sickmm/enginehowl1.wmv

http://midwestpanthers.net/sickmm/howl2.wmv

Any and all ideas are appreciated...

[DEFYANT]

Ok, taking another look..

Did you run the engine w/o the blower or accessory belts? Can you do that for a very short time to diagnois the problem?

Have you checked the oil for metal? Perhaps send out a sample of oil to Blackstone labs?

[Zack]

Dont feel bad, I heard the exact same noise on an MM yesterday.
Clueless as to what it is.

[Smokie]

Your noise sounds to me like a moving part barely rubbing a stationary part...both are metal. The fact after warming up it gets better not worse suggests to me that heat expansion is creating a gap between the rubbing parts...I am not familiar with bearings that get quieter the longer they run.

This may sound primitive to you, but I use a hollow metal pipe to trace origin of noises, about 2 to 2 1/2 feet long...it works rather well.

This is ^^^^ what I thought the first time around. Removing the blower belt eliminated quite a few posibilities. Still believe it is moving part slightly rubbing stationary part, second guess alternator bearings.
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[Bobby Clobber]

Jason,

Did you check the clearance between the alt bracket and the pulley that the bracket is cut out for? That clearance is very tight and if that bracket is warped, ( another thread) it could be rubbing.

Incidently , my squeal, not unlike yours seems to be gone now that I installed the Gatorback drive belt. Still have the Gates blower belt.

Good luck, Bob.

[SergntMac]

All I will suggest is the tensioner pulley. They are a known weak spot. I've replaced one on every Marauder I have owned, one twice...That's 4. Several folks here have posted about replacing it too. Guess they just can't handle the constant run through the higher RPMs, and get noisey.

Haven't had one fail on me per se, but the noise gets on my nerves after a while. The tensioner is not expensive, but a PITA to change on blower cars.

Just my .02C, carry on gents.

[Rider90]

I replaced the belt tensioner & pulley (Both came preassembled bolted together) this evening and the noise is still present.

Does anyone know the P/N for both idler pulleys? IIRC the Trilogy kit replaced one of them though.

[Glenn]

I also have an engine noise, but it is a squealing mainly noticable at cold start-up that now only lasts a minute or so and only on accelerating the engine. I have replaced the tensioner, alternator bracket idler pulley (from Trilogy). I have a new alternator bracket from Trilogy and a Gaterback belt to install. But, the noise has diminished considerably and I hardly notice it anymore. I will eventually put on the new bracket and belt.

From listening to your video tape the constant howling sounds more like you have not done the requried K&N SC mod to your PVC intake tubing to the K&N intake runner. It is a mod that has been covered in detail on the net.

Upon listening several more times to the video, it really sounds more like a bearing noise. But, did you already do the K&N CAI PVC SC tubing mod?

Glenn