Hi all,

XJ8 4.0.

Startet my car today and a high pitched whining noise was quite audible. I took a short drive, but noise is still there, although a little better but quite noticeable a slower speeds.

The noise follows the engine revs, also at stand still in "park", so it can't be gearbox/drivetrain related?

It is difficult to identify where he noise comes from but it's either the front or right side. Can it be bearing in water pump or alternator? No error messages on dash or errors in obd2 reading.

Any suggestions how to identify or most likely culprit?

Thank you very much in advance.

 

My first guess would be the idler pulley. It's between the alternator and balancer. Try spraying a little WD-40 on the bearing, not the belt, and see if the sound inproves. If it is replace at your earliest convenience. Two weeks ago my wife was driving our XJ8 and the alternator light came on and she lost power steering. Told to not drive it any further because if she did it would overheat because the belt was gone. When I checked it the idler wad gone because of a bad bearing.

Note: shut motor off when you spray the WD -40.

 

That's the supercharger! Haha
All joking aside, does it only happen when the engine is running? Is it a whine or is it a hiss?

Mine makes a whining sound when it's in accessory mode and for about 10 seconds after I shut it off, comes from the engine bay.
If it's more like a hiss, could be a slight vacuum leak (mine has this, doesn't not affect performance or anything, doesn't throw any codes).

 

Thanks Bobroy an bcrary

Tried WD40 on pulleys/bearings, but noise is the same. This is the 4.0 non-supercharged engine btw.

It is a high pitched whining noise and the noise started today, ok yesterday. Not a hiss, engine behaves as responsive as before. The best way I can describe it is like in the old days if you didn't shield your soundsystem, a whining noise came trough speakers and follows engine revs/gear shifts. (It is definately not the stereo :-)

Yes, only when engine is running.

Any other suggestions?

 

Is the noise from the front of the engine? If it is take the belt off and see if the noise stops. Don't run it very long because you will overheat. If the noise stops try turning each pulley by hand, with the belt still off, to see which one is making the noise.

 

Hi,

Just came from the garage due to a oil shift, and they had a listen to the whining noise. They deducted that it was not coming from alternator, waterpump or pulleys. They said it was related to air intake somehow. This is a Ford garage and not a Jaguar specialist. They would like to have the car in for a more thorough check.

If this is an air leak, any suggestions where to look? With hourly rates at $150 in Norway, I would love to try to fix this myself...:-)

Thank you for any replies.

 

Take a little (and I mean A VERY LITTLE) brake cleaner and spray just a bit around all of the fittings and air hoses, if the engine starts struggling (sounding like it's about to stall) you found your air leak. My car makes a hissing sound due to an air leak, but it hasn't affected the drivability of the vehicle so I just deal with it.

 

Remove the air intake hose and inspect it for cracks, especially the underside bellows area. Then check the vacuum hoses that connect to the intake manifold.
When you put the air intake back on the throttle body make sure the rubber ring fits tight.

 

Thanks a lot Bcrary and RJ237.

Tried with a little cleaner on hoses/fittings, no results. Removed air filter, box and air intake hose. Cleaned and replaced. Breather hose is only a couple of months old, but checked and cleaned. Checked all hoses I could find. No result, sound is still there.

But listening closely, I can't find other sound source than around the thermostat housing/waterpump or front right side (see pic). My best guess will be waterpump/impeller? I am to change to upgraded aluminium housing anyway.

I am a bit OCD about unwanted noises and it is starting to get me :-).

Any other tests or diagnostic tips or do I wait after waperpump/housing change?

 

Remove the serpentine belt and run the engine briefly. If the sound is gone check all the pulleys and idler/tensioner bearings.

 

I'd replace that bypass hose ASAP! Looks like it's about to blow.

 

You mean the "breathing hose" below the red circle on pic? It is completely new?! Bends a bit due to new plastic. Can I try to remove it and start engine briefly?

 

Oh, I guess you mean the short hose on termostat housing? Yes, it is a bit "blubby" but by inspection it feels ok. No abnormal pressure, just tight fitting. I will replace it together with new housing and water pump.

 

Bcrary3 is referring to the short coolant hose between the crossover pipe and the thermostat tower. It does appear to be bulging and should be replaced. It would also be a good idea to replace the thermostat tower, thermostat and crossover pipe. An aluminum tower is available.

Have you removed the serpentine belt and run the engine briefly to listen for whinning sound yet?

 

Thanks again both of you.

Yes I will replace the hose, already ordered.

Unfortunately, I am not too tech savvy, but I have an appointment with my garage on friday and I will tell them to remove belt and check.

I let you know the result.

 

Hi,

Came back from garage and it was confirmed it was the idler pulley.

Thanks for all comments and help.

 

Hi,

Came back from garage and it was confirmed it was the idler pulley.

Thanks for all comments and help.

 

Glad to hear you got it resolved. Thanks for letting us know. Some members get advice and you never here from them again. It's nice to know what the solution is because we, especially me, can learn more ourselves to help solve other problems in the future.

Happy motoring.