I have a 3.0 Jaguar X type Sport Automatic with almost 95k miles on it.
It started making a strange noise which I pin pointed to what I believe is the A/C compressor but have not replaced it yet.
The noise used to come when I only had the A/C on but now it appears to be constant at low rpm.
I can only hear it with the windows down but it echoes and is pretty embarrassing.
he noise sounds almost like a sputter but I cant exactly describe it, I did check and it is not coming from "inside" the engine.

A little background in the last two weeks.
I changed the serpentine belt, belt tensioner, changed the oil to Royal Purple Full Synthetic 5w-30, changed the spark plugs, cleaned the throttle body and air flow sensor, replaced air filter with K&N filter.

The bottom line is after reading a forum on here I thought the belt tensioner may be the problem.
It was not, the car is still making the noise even with the A/C off. I was wondering if anyone has any advice, like I said I just did a major tune up on the car and the noise is still there.
I am thinking about replacing the A/C compressor as I wonder if it is the pulley/clutch on the compressor, but I don't want to further over invest my self without results.

This is my second X-type and your forum has really helped me in the past. Any advice would be appreciated. Thank you!!

 

Alex, I've moved your post to the X type section where you'll get the best help.
I put some line breaks in to help readability.

 

It could be the A/C compressor pulley bearing. When the A/C is off the
compressor does not spin but the pulley does. When a A/C is on
a magnetic clutch connects the compressor to the pulley.

You can check it by removing the belt and spinning the pulley by hand.
It should spin freely and smooth. You can also check all the other
accessories at the same time.

Often the A/C pulley bearing can be replaced without breaking the
compressor seal and losing the freon.

Pete.

 

Alex, after you do what Pete suggests (good advice, Pete) be sure to report findings here, resolved or not. Because if that's not it, folks here will help you walk it down then we'll all know "what causes that???"

While you have the belt loose, be sure to give the alternator a spin, that should be free, smooth, and quiet as well.

If the noise changes considerably with the engine running, and as you turn the wheel back and forth while parked, you may be looking at the power steering pump.

 

[QUOTE=AlfaVeloce;735175]Alex, after you do what Pete suggests (good advice, Pete) be sure to report findings here, resolved or not. Because if that's not it, folks here will help you walk it down then we'll all know "what causes that???"

Thank you guys for the advice! I definitely will let you know. A friend of mine owns a shop with lifts and im going to check all the pulleys next weekend and will let you know what I find. I wish I would have asked you guys before I put the new tensioner and belt on Lol

 

Alright so we were finally able to get the car on the lift and list for the noise with a stethoscope. The noise is not coming from any of the pulleys, instead it is coming from underneath where the engine and transmission meet. The noise is somewhat quiet when the A/C is off but when the extra load on the engine is exerted it is very loud. From what we could determine it is coming from the flex plate, torque converter area in the spinning mass between the engine and tranny. Do you guys have any suggestions? This just turned into something a lot more complicated than anticipated. Thank you again for your help!

 

The first time around we found out that it was the flex plate bolts that were making that noise. I just recently had this noise come back and had the flex plate and torque converter replaced. However, the whole front of the car vibrates now and the steering shakes at 60 mph. Do you think I should have shop double check to make sure the mounts were re-seated properly?

 

Also the knock is still there and I noticed it is worse with the compressor on. I am going to buy a new compressor, mine was leaking oil for a little while and I think it could be the culprit, I also ordered a new crankshaft pulley to see if that helps with the vibration issue. My wife says she can feel the knock on her side of the car (where the belt is).

 

If you think that the noise is coming from one of the belt driven accessories you can remove the belt and drive around for a short time. That will answer the question about the A/C pump. Pete.

 

Sorry, I neglected this post. It turns out the issue was torque converter and the flex plate. Additionally, I also had to replace the A/C compressor as it failed completely. Between those things the noise is now resolved. Thank you all for your help!

 

Also the vibration issue was the result of two broken motor mounts. We were side swiped back in the fall and the body shop completely missed the fact that the engine mounts were damaged.