Since the initial post of this thread I have determined the cause of the noise, therefore, I changed the title, and am positing new info here at the top:

Now that I have confirmed that the A/C compressor needs to be replaced, I called the Jaguar dealer and was quted over $1200 for the compressor, not inlcuding the other parts they want to install, such as a new receiver dryer, etc, and that does't include labor either. I was suprised however when I was told that I can source my own compressor and they will install it, however, if there is any kind of issue with the compressor they won't warranty their labor. That is fair. So, I have been searching for a compressor and found some from $200 up to $1400.

A/C Compressor Four Seasons 97341

The autoparts shop at the link seems to have the best price. Has anyone ever used one of these? Does anyone have any other sources, thoughts, or recommendations based on experience?


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Old portion of thread below:


Recently I started hearing an intermittent 1/2 second grinding sort of noise coming from the engine compartment, noticed only very occasionaly at very slow speeds (presumably this is the only time I would be able to hear it without wind and road noise). Once, while coming to a stop light it made this noise but didn't stop for about 30 seconds. It almost sounded like a cooling fan that was going bad, but it was not coming from the cooling fan area, rather, like from behind the engine near the bell housing. Then it just stopped all on its own. It has not lasted more than a second since that one time. Today, from a cold start in the garage, with the hood opened, I stood there watching and listening, all was fine. My cooling fans were working, the A/C compressor working and sounded fine, alternator sounds fine. The engine was at full operating temperature, and then I heard it again, without question, this very brief noise came from near the throttle body area, maybe even just behind it between it and the firewall. It was so short of a duration that I could not pinpoint the location any better, and it never did it again. However, it seemed (and I think I noticed sometimes when parking the car sometimes) to be a subtle but slightly noisier consistent sound, almost a whirr or something, from this area - bit not the typical and normal constant whirr or humm that comes from the throttle body normally. It doesn't really change with engne speed. I shut off the car, restarted, and it was noticeably quieter again, but it didn't come back (I gave up after a few mins). I know this is vague, but has anyone experienced this? Is there some kind of electric motor or solendoid in this area that maybe turns on or opens allowing an air pumps to pump air into the throttle body? Also, I think there is an electric coolant pump motor near the firewall area to feed the heater in the car, has this been known to make strange noises?

 

You mention that the sound may be near the bell housing...could it be your gearbox?

A while back, I noticed my gearbox making a short, relatively quiet mechanical whirring noise during shifts from first to second, only if the gearbox was cold, usually first thing in the morning. Could only really hear it if the windows were down. Turns out I was a bit low on transmission fluid, and a top off made the noise disappear.

Try to judge whether you hear the noise during shifts or not.

Just a thought.

 

Check to make sure your trans is not low on fluid. They will make a grinding noise like that when fluid is a quart or more under.

 

Thanks, I am 99% sure it is not from the transmission. I sensed when listening today with the hood open that is was higher than the bell housing. I know for a fact it has nothing to due with shifting though. It makes this noise is park, neutral, gear, and always is constant pitch. I can't help but think it could be the coolant electric motor, but I can't really see where that is located.

 

I found the problem, it is the A/C compressor. Sometimes the compressor makes a whining noise, seems more prevalent when it has been running for a while. For instance, at cold start, the compressor seems quiet, and I know it is engaged because if I shut off the climate control, I clearly hear the clutch disengage. So, sometimes when the compressor kicks on it makes a split second grinding noise, then is ok, except the whine is usually still present. I believe I will need a new compressor soon. I don't think the compressor is a common failure, not unheard of, but it does seem to be fairly reliable for most. Has anyone heard such a grinding noise? I presume such a noise is a warning sign?

 

FWIW mine is a little on the noisy side too but still comparable with others cars I have owned so I haven't given it much thought.

You might check the pressures in the system and adjust accordingly. Even if they are correct you could try having the system evacuated and refilled with fresh refrigerant and lubricant before going so far as to replace the compressor.

 

Usually but not always, a dying compressor tends to exhibit visible refrigerant green-colored dye leaks at its hose fittings. Most of the time you must crawl underneath the car to be able to see them up close. You may want to jack up your car and have a look. The owner of the Midas shop in our area is always willing to put my vehicles on a hydraulic lift and allow me to fully inspect the underside with them for free. Some A/C shops may be willing to do the same....

 

When the factory compressor on our 2005 S-Type began to give up the ghost in May 2010, it sounded normal with me standing over the engine bay and leaning down while listening with the engine idling and the A/C running full blast. But when I jacked up the front end of the car, crawled underneath with my mechanic's stethoscope, placed its tip on the compressor housing while running, and listened through its earpieces, the compressor sounded like a cement mixer full of gravel due to its bearings wearing out. I knew then that the compressor was doomed to fail. The first sign of impending failure was the A/C system's inability to cool the cabin sufficiently on days when the outside temperature was above 85 degrees or so. Within a week or so, the A/C system would barely cool at all. A new compressor restored the A/C system to full arctic mode, and it has been fine ever since....

 

Now that I have confirmed that the A/C compressor needs to be replaced, I called the Jaguar dealer and was quted over $1200 for the compressor, not inlcuding the other parts they want to install, such as a new receiver dryer, etc, and that does't include labor either. I was suprised however when I was told that I can source my own compressor and they will install it, however, if there is any kind of issue with the compressor they won't warranty their labor. That is fair. So, I have been searching for a compressor and found some from $200 up to $1400.

A/C Compressor Four Seasons 97341

The autoparts shop at the link seems to have the best price. Has anyone ever used one of these? Does anyone have any other sources, thoughts, or recommendations based on experience?

 

You'll probably get a better all-around deal at an automotive A/C specialty shop. I would call around and see what you discover. If you're an AAA Motor Club member, their shops tend to be qualified and fairly priced. Your membership also gets you a discount on labor as well as a 24-month/24,000-mile warranty....

 

Forget about having a dealer doing the work. You'll still pay through the nose. I agree w/ Jon89. Check out local auto AC shops. You'll get the whole job done at one shop, obligating them to insure the system is fixed and working properly. As you have already discovered, bringing your own parts to the table basically disqualifies you from getting any sort of performance guarantee from the installer.

 

Is it possible to rebuild these units yourself, or is it best to leave it alone and get a shop to do it?

 

After more careful diagnosis with my stethoscope I am happy to report I don't have an A/C compressor issue, but rather, my auxiliary water pump for the interior heater is going bad. I have 2 questions: are all years interchangeable? On eBay there are several used pumps such as Jaguar 98 XK8 Auxiliary Heater Water Pump MJA6710AA | eBay

But I can't tell from any Internet sources if they are all the same. Also, how in the world does one get into the area to replace this...it really is buried. Please tell me it is easier than it seems. Has anyone replaced this themselves, any guidance?