Low frequency noise/growl from front end passenger side

[sarg]

Ok I swear I am about to light the car on fire .....getting annoyed with this. Replaced the calipers and rotors and pads with all new stuff up front (both sides). Hubs have been replaced, axle, and checked the disconnect. My wife went to start up the truck so I could bleed out the brakes with the new caliper and the noise on the passenger side happens with the truck sitting still with me right there. I could not get it to reproduce it, but it obviously has NOTHING to do with the brakes, axles, anything as far as I can tell. The car was sitting still.

I am assuming (and I know what assuming does) that the front drive system is not moving in any way shape or form when sitting still with the car in park. The only things I can think of is that either:

A. the antilock system is kicking in briefly for some unknown reason, although I don't think this to be the case as the car was sitting still and it has a new wheel speed sensor, courtesy of the new hub. It is most definitely coming from the passenger side.

B. Maybe the tensioner is locking up and creating a drag and it just sounds like it is coming from the lower wheel well as the noise is translated out that area.

C. The compressor is going bad.

But it is doing it bad enough that the car kind of bogs down almost like the brakes are being applied, hence the reason I thought it was hub, axle or brakes. Any ideas fellas?

 

[doug383]

K most of my experience is wit LT1's and LS series but my money is on the a/c pump.

Do you have a mechanics stethoscope?

 

[sarg]

This is a LS series motor. 5.3 LS motor. I do own an electronic stethoscope, but the noise is very unpredictable and erratic. It surprised the crap out of me when it happened. I did have it happen once before when backing up and stopped. It surprised me but I took it as the brakes must have been loaded and making a similar noise. It feels like a kind of shutter. When going down the road you can feel it slow the truck down. It sounded like brake moan when barely going backwards.

 

[doug383]

I would be lead to suspect a bad bearing on the a/c pump or alternator. Is the a/c working correctly? Or any other pulley on the belt. On my old LT1 the bearing in the alternator went out. I didn't have a stethoscope so I used a 24" extension, placed one end on the alternator and the other to my ear. It helped hear where the groan was coming from.

 

[sarg]

it is definitely caused by the Ac system. I have narrowed it down to that and attempted to change the tensioner and belts in hopes that it might solve it. No such luck. At this point it is either the compressor or the clutch. The weird part is the compressor works and everything cools as supposed to. it just makes a horrid racket at first and will seriously bog the motor even when cruising.

 

[doug383]

It still could be a bearing on the a/c

 

[Texan]

To me, the real question is: Is it the A/C compressor clutch bearing, or the compressor itself.

 

[sarg]

I agree Texan, any ideas how to tell? I do k ow it only makes the noise then the ac is turned on, which leads me to believe it is probablt the compressor itself.

 

[doug383]

If it is only happening while the a/c is on the compressor culprit. Other wise it would do it nonstop.

 

[sarg]

Kind of what I was thinking. Sucks just paid to charge the system after fixing a leak too.

 

[Texan]

Could it be over charged? You do not want to slug the compressor with liquid Freon.

 

[sarg]

My friend did it on one of those fancy machines. Thinking probably not.

 

[sarg]

Could it be over charged? You do not want to slug the compressor with liquid Freon.

It was in fact overcharged. You hit the nail on the head. We thought since it had ac control in the back it was rear ac and charged it as such. After a lesson from Roadie that the short wheel base do not have the rear ac unit, we sucked it all out, recharged with the correct amount and BANG! No more ac issues or weird noises.