B Feelgood

So I am trying to track down the culprit that is making a loud whining/groaning noise. I start the car up when the engine is cold, get the normal loud whine for about 30-45 seconds, and then it persists after that instead of disappearing "imagine the cold startup whine/groan but it nevers stops." First I took the supercharger belt off, started the car and it was still there. So I then took the serpentine belt off, started it again, and the noise was still there. I spun all the pulleys by hand and checked for play in them. The supercharger idler pulley was making a noise when spun and did not spin as freely as it should so I changed it with the ASP one. All the other pulleys spun freely and without noise except for what I believe is the A/C compressor pulley. It does not spin as freely as it should and also makes some noise while spinning it by hand.

#1 Is there a replacement pulley for the A/C compressor or do you have to buy the entire compressor assembly?

#2 Is there a way to temporarily disconnect the A/C compressor to see if the noise disappears?

The noise comes from drivers side and is down low. I have had two other SL55's and they did not make this persistent noise. The noise is there whether the AC is on or not and seem to intensify with throttle when the car is idling.

shardul

iTrader: (1)

when the serpentine belt is off does the a/c compressor is also not spinning, so i think the noise is coming for some where else. correct me if i am wrong

vioilio

If the noise is still there after removing the belts then your noise is not connected to a belt driven component. Try and listen around the transmission. It could be your pump. When was the last time you check your transmission fluid level?

shardul

iTrader: (1)

do you hear the noise if the car is in neutral?

B Feelgood

Thanks guys... What you are saying makes sense. The noise is still present and does not change whether the belts are on or off. I thought the A/C compressor still might be doing something if there was an electrical current running to it.

The noise is the loudest if you put your head down by the drivers side front wheel. I checked the power steering fluid and it is filled correctly but have not checked the transmission fluid yet.

B Feelgood

Great question. I have only tried diagnosing it while the car was in park. I will try this in about an hour and report back here.

B Feelgood

The whine/groan noise is present whether the car is in P,D,N,R. It gets faster/louder with RPM. An other ideas?

B Feelgood

BUMP... Car is a 2006 with 29K and is the most noticeable in 1st gear in the lower RPMS

pearlpower

Jack up the car, block the wheels, jackstands, and start her up. Let us know.

shardul

iTrader: (1)

Could be one of the idler pulleys going bad

pearlpower

B Feelgood

So basically you are saying to put the car on jackstands and start it while the car is in the air without the tires touching the ground? What exactly would this be testing for?

pearlpower

Isolating the noise. If you have a stethoscope that would also help.
Just be careful as there are very hot items under there as well as rotating metal. But jack it up, secure car, start it up, and look in the area you feel the noise is coming from. Simple.
http://www.harborfreight.com/mechani...ope-41966.html

B Feelgood

UPDATE: Dropped the car off at the stealership this morning and they just called back with their findings. They said "we took both belts off and the groan/whine noise was still present." They say that the Air Conditioning compressor is making the noise and that the pulley is wobbling "which I already knew about the pulley." They said the bearings inside the compressor are what is making the noise. They want to replace the air conditioning compressor, condenser, and evac/refill the system for the low price of $2,225.

Couple of questions. The noise is present whether or not the air conditioning is turned on/off and is present with/without the belt. How could this still be making the noise? Is the compressor still running from electrical current without the belt driving it? The air conditioning blows cold air at the moment with no problem. Has anyone replaced the compressor themselves or just the bearings inside?

pearlpower

if they removed the belts and nothing is spinning the compressor how could it be making noise??????

B Feelgood

That is what I was thinking to myself when I was talking to this service adviser on the phone. I didn't want to question him until I posted their "results" here are the forum. Whenever I had both belts off, I did notice the A/C compressor pulley had some play in it when spun by hand and could probably be replaced. That obviously was not the source of the noise however since it is still present with the belt off and the pulley not spinning. I just wanted to make sure that the compressor didn't receive an electrical current or something that kept some part of it moving without the belt.

I told them to keep the car until tomorrow morning and that I would give them a call back at that time. I don't know if I should just pick the car up and tell them not to replace anything or ask to speak with the mechanic and have him explain how the compressor could still be the source of the noise without the belt on.

kustom2k1

bfeel, I need to have mine changed and luckily know a master MB tech that agreed to change my unit and all associated parts for 1k. If the diagnosis is correct, take your back and shop around for a good indy shop.

Not sure where you live but if your in SFL. I'm sure you can get the same price.

B Feelgood

Just uploaded a video I took when I was trying to isolate the noise with the belts off a couple of weeks ago.

B Feelgood

Does your SL have the same symptoms as the ones I described above? Check out the video and let me know if yours makes the same noise. I am from PA.

kustom2k1

Sorry B, my cars compressor does not make noise. The pressure stays too high. I spoke to my tech and he says, the dealer uses a smaller belt to bypass the AC compressor for testing. He also says, the AC should not make noise with the belt off. Hope this helps.

xpl0sive

sounds like a regular 55k noise to me. people have said it's the engine oil pump or the transmission oil pump but every 55k engine i've heard makes that noise...

B Feelgood

Kustom, thanks for the info. I'm not sure what else I could tell them to check for that might be making the noise. There is no way I am paying over $2,000 for the AC compressor when it is probably fine. This 2006 has 29k miles on it.

Xplosive: Before this 2006 SL55 that I currently have, I owned a 2003 SL55 that had 42k miles and a 2006 SL55 that had 24K miles. Neither of the other two SL's that I have owned made this loud noise. I noticed it immediately after receiving the vehicle but did not think much of it. It is especially noticeable when I am in a parking garage and I keep the car in first gear while driving inside of it. The whine/groan noise is almost louder than the exhaust noise and I have the resonators removed from my exhaust.

kustom2k1

B, does your AC work? Did they check the ABC pump? Do you see any signs of oil?

B Feelgood

The air conditioning seems to work fine. Gets nice and cold quickly. They did not say anything about the ABC pump, just immediately wanted to do repair work to the compressor. No signs of anything leaking or dripping coming from the car. I did an oil change and spark plug change myself about three weeks ago and thoroughly inspected the car and did not see any signs of leakage coming from anywhere. Also when the car was in for the state inspection I checked all the struts/suspension stuff while the wheels were off and everything looked nice and dry there as well.

B Feelgood

Just talked to the service adviser this morning. I explained to him that it would make sense for the noise to stop whenever the belt is taken off and or the AC was turned on/off from inside the car. That would in theory take the AC compressor offline since the pulley is what provides the power for it. He confirmed again that the tech took both belts off and noticed the noise was still present. He did not confirm if the tech had said the noise was still present when turning on/off the AC from inside the car. His explanation for their findings was that the bearings inside the AC compressor were failing and creating a chattering sound and that the propeller shaft was loose causing it to vibrate thus making the whining noise. Did not know why the noise would get louder with RPM.

After he told me that, I just told him to have the tech check all the fluids including the transmission and I would be in to pick up the car in a few hours. I apologize for rambling but one would think the technicians at the dealership would be the best at what they do. Having them suggest to change out the entire AC system when it works fine on a car with only 29K miles seems mischievous. The only other dealership is about 25 miles away from me.