If the XJS has been sitting over 24 hours, when it is first started there is an unpleasant noise coming I think from the A/C Compressor.

Sound File attached.

As you can hear, It goes away fairly quickly, and won't do it again if the car is restarted. However, that noise can't be good thing. Maybe low on PAG oil?

Help appreciated.

 

Unplug the compressor so the pulley isn't loaded when you start the engine. Any change?

Might be a belt making noise. Might be the harmonic balancer delaminating

Cheers
DD

 

I'll have to wait at least 24 hours to test that.

 

Sounds a little like belt noise (loose or misaligned).

Get a large block of hand soap and hold gently against each side of the compressor belt but be very careful with your fingers. If the noise disappears momentarily it is the belt if not then it is something else. If it is the belt you could try applying a little bit of silicone grease to it.

Good luck,
LeeP

 

This morning, I unplugged the compressor and there was no change.

 

Do you have an idler bearing on your car? Mine made a noise like that iirc..I replaced it

 

That sound might very well be your delaminated harmonic balancer - lots of threads in the archive on repair/replacement. Just did mine last year.

Larry

 

My friend recently caught this sound on XJ81. He will send the damper to the Damper Doctor. if you will turn to DD then tell as how it was. Please.

 

Here is an update:

I checked all the belts and found the AC Compressor belt had a little extra slack so tightened it to about 1/2" of play, but it still made the noise the next morning. Experimented with it tightened to 3/8", still no joy the next day so I backed back off to 1/2". The having to wait 24 hours between starts for the noise to repeat was making it hard to diagnose.

Decided that I needed someone else to start the car so I could stick my head under the hood and see if I could pinpoint the location of the noise. Wouldn't you know it... first time with my daughter starting the car it doesn't make the noise. Go to drive it an hour later, it makes the noise! Ha. Now, four mornings in row, it won't make the noise when I have someone else start it for me. Maybe the adjusted belt is 'settling in' or maybe Sir William's ghost is having a laugh at my expense. Why do I have the feeling that the next time I go solo to start the car, it will make the noise?

Ahh, the charm of these beasts.

Cheers