My 2006 XK8 started making an engine whine a couple of weeks ago. Took it to my nearby independent shop and the diagnosis was it was probably the water pump. Could not be sure, but that was the most likely source. So they replaced the water pump. Seemed to cure the whine but a couple of days later the same whine came back.

The pulleys (not sure if that is the right term) were replaced. Whine still there.

Suspected the power steering pump. Replaced it. Whine still there. Reinstalled the old pump.

Going to change the alternator to see if that is the source. Maybe it is.

Mechanic says he is pretty sure it is not the air conditioner compressor. The sound does not seem to come from it (he uses a stethoscope).

They said when the belt is off and the motor is started the whine goes away, so that is evidence the source is something the belt touches.

If it is not the alternator, what else could cause the whine??

Is there a harmonic balancer on the car? If so could that cause the whine?

The engine runs fine. No codes.

Thank you,

Jack

 

I would have left the new PS since it was done.

 

did the belt tensioner get replaced?

 

In my (admittedly limited) experience, belt whine is usually contamination on the belt. Typically, a dying water pump drips and splashes coolant around, which eventually sort of dries but manages to capture dirt on the belt. Besides fixing the root cause, the belt and pulleys needs to be cleaned. Engine running, I have used a solution of hot water and Simple Green generously sprayed around the entire area of the belt (I have used a spraying wand off of my air compressor). That has fixed it for me (it was not my XK8).

You could apply this fix easily enough. If the whine immediately stops when the belt is wet, you have identified the issue. If not, it might help eliminate the belt as the source of the issue, and with the belt completely quiet, help you pinpoint another source of noise.

PS: Resist the urge to apply those belt sprays from the parts store. In my opinion, they are made for the sole purpose of facilitating the sale of a car, and are temporary at best. Belts are meant to operate as-is, no goop is necessary.

Best of luck, keep us posted.

 

Yes. Replaced after the water pump did not cure the whine.

Thank you,

Jack

 

I guess the mechanic did not leave it on because he does not want to replace parts and run up my bill searching for the answer. Maybe if he called me and asked me if I wanted it left on I would have said yes.

Thank you,

Jack

 

The mechanic does not think it is the belt itself. We talked about that. It has not been replaced.

Still a bit of a mystery.

Thank you,

Jack

 

Another strategy would be to try and vary the load on each accessory, one at a time, and see if the whine changes.

To test the alternator, turn electric stuff on, like headlights, brake lights, heater blower, cigar lighter, radiator fans, etc.

For the power steering pump, slowly turn the wheel with the car on the ground, stationary.

For the AC compressor, turn it off, then on. You should be able to tell when the clutch engages and disengages.

Also, check the basics: when the belt is off, turn each accessory and pulley by hand, and check for excessive drag, if any is greasy to the touch, or has any play. Also check if any is possibly out of alignment with the rest, if you cannot keep the belt in the proper grooves.

 

Yep, I think they have tried all of this. Except the alternator stuff which they are doing now.

It would be quite something if it turned out to be just the belt after all this. They do not think it is the belt.

Thank you,

Jack

 

Typical of the problem with today's "mechanics". If they can't read a code they are totally stumped.

Doug

 

Doug,

I do not think that is the case here. The mechanic has been a mechanic for a very long time and has a lot of experience. I am 66 years old. He is older than me. He was working on English cars long before there were "codes".

I do not blame him for anything. He is a good mechanic and a good man.

However, right now he is stumped. He is not giving up. He will figure this out. I posted this in hopes that others might have had a similar experience and could shed some light on what they found.

Thank you,

Jack

 

Just got the car back from the shop. When the alternator was replaced the whine went away. The old one tested good, but had the whine.

Hopefully it is not a temporary fix. Hopefully the whine is gone. If not I will post. But for now.... problem solved.

Thank you,

Jack

 

I'd think the old one getting "bench" tested could have not brought out the sound when it was installed and under load.

 

Well the whine was probably a dry bearing about to get much worse so replacing the accessory that had the bad bearing makes sense. Back in the day, you could just replace the bearing. Probably not worth it these days, just put in a rebuilt unit.