I have a humming sound from like 30 on. I am going to replace the front wheel bearings soon. I suspect that is the source of the noise.
-Rob

Well, I drove the jag yesterday, and my '98 also makes a very quiet and subtle hum between ~52-55mph under load in normal mode. Very quiet as in had to turn the radio all the way off and avoid pulling alongside any large trucks. That said, mine only has 38k miles on it, which makes me a little suspicious of the suggestion that the transmission is going. So I'm waiting with baited breath to see what Bob comes up with...

(Has anyone verified that the hum is NOT normally present at 52-55 under load in normal mode?)

Well, this kind of sounds like my current problem. I have always heard a hum when the car was cruising around 55 - 60. Now, for the last week I hear a rattle/rumble when the car is in a pull. At first at was only around 50-55 today I noticed that when in OD in town (normal mode) on in incline the rattle/rumble appears. I drove yesterday only in S mode same problem may higher speed. Took the car to AAMCO who just rebuilt the trans last July the message I got on the answering machine was "It's not the transmission". It just seems that the timing of the noise would lead you to believe otherwise. Maybe one day we will find an answer.

Well, if you're waiting with bated breath to see what Bob comes up with, you may be waiting a long time. Earlier in this thread, Sparkenzap told us that 52-55mph is the speed the TC locks up in normal mode so I have been trying to duplicate the noise at a higher speed in S mode and so far have not been able to do that. Unfortunately I don't do a lot of highway driving and have very limited opportunities to drive at higher speeds. I have tried different higher speeds up to 65-70mph and don't hear the noise but since road and wind noise is greater at those speeds, the noise may be there and I just can't hear it.
Does anyone have access to tech info that would give us the lockup speed in S mode? If I had this info, it would be a lot easier to listen for the hum instead of trying to search for it at different speeds.
Bob

Great thread. I've had my 98 for a few weeks and have noticed the same sound at 90 kph, or 55 mph. I'll do what I can to narrow it down. Keep the ideas coming!

I don't have much new to add to this thread except that on a short trip last week I had opportunity to drive at speeds up to 75mph in both regular and S modes. Same hum in regular mode at 52-55mph; in S mode I tried different steady speeds up to 75mph and did not hear any hum. However, as I have pointed out previously, there are other noises at those higher speeds and the hum may be there but I was unable to hear it. Based on the many posts to this thread, I agree that the problem seems to be the torque converter lock up. Since I don't drive in the regular mode, I am not concious of the noise and certainly am not going to the expense of a tear down. I'll live with it unless it get worse. Thanks for all your help.
Bob

My 2 cents...
 

I know this thread is a bit older, but I have been having a similar noise and have been trying to diagnose myself. I have not spent much time tracking the noise yet, however I have just completed a transmission rebuild with new a-drum and valve body. I believe that the torque converter lockup is throwing you off the track a bit. Here is my take on how the torque converter lockup is changing the noise.

Since the torque converter locks up at this speed range it is allowing the engine to deliver direct torque to the drive train. This in turn may be putting more strain on the drive train in turn causing one or several of those components (prop shaft, rear diff, half shafts, or rear wheel bearings) to have more strain on them and thereby causing them to hum. I believe the noise is coming from the drive train and not the transmission. Just my personal opinion. Hopefully as time allows I will be able to start tracking down this problem.

These cars do have a problem with a weeping rear pinion seal, in which it allows the rear differential to get low on fluid. This can present many problems, especially if a shop has changed that pinion seal. I know that mine has been changed and as far as I know the only real way to check the bearing pre-load on a differential, you have to remove it from the vehicle. Most of these shops will not remove the differential to change the seal and they rely on tightening the nut back to its original position as a means of getting the bearing pre-load close to what is should be. I am guessing that this could be just one of the many things in the drive train that could be causing the hum from the car.

I will try to update as I move forward with my investigation into this noise.
If there are any techs that would like to weigh in on my theories, I would definitely appreciate it. Especially since thats all these are, are theories.

Thanks all

I had the same noise, took me ages to find out what was the source, but now it's gone with only remedy to retorque the diff pinon nut, please search my thread about diff noise for more info and instructions for work. Good luck!

I've had a vibration rather than hum on my 98 for several years now but the symptoms are all the same as those on this thread. I've spent a lot of time & effort trying to get rid of the vibration, but never succeeded. The maddening thing has been that it comes on at 45-55 and often fades by 70+. There are (rare) times when, on the same road, it never appears.

Right now I'm in process of a transmission rebuild as I experienced a failure last week I suspect to be a faulty A drum. On reading up on the issues with the transmission as I pondered doing the job, I got to wondering if my problem may be in the Torque converter and will look at it as I have things on the bench to see if there are issues there that could be causing lock up problems leading to vibration (Hopefully, the tranny comes out tomorrow & I'll be able to look at things on the bench. Today I got the exhaust off and all but the torque converter bolts off).

However, in line with some other comments, the principal area of suspicion is in the rear end and, in my case, the U-joints. I replaced one a few years back when it went bad & the vibration improved afterwards, but never disappeared. I regret not doing at least its mate on the half shaft. The interesting thing with the U-joint I replaced is that only 1 trunnion was bad & clearly had not been getting grease delivered to it when I did the annual routine. I continue to suspect that one or more of the others has also got a dry trunnion & is in a bad enough state to contribute to the vibration w/o being obviously bad.

My 2 cents...........

XJRJeff:
Your point is certainly valid. The observation that it happens at lockup speed does not prove it is at all related to the torque converter itself. In my MY02 XJ8, the hum has been there since about 100,000 miles and it is currently at 170,000. I am fairly certain it has not gotten worse in that time.

BTW, I first noticed it some time after the first time I changed the tranny fluid. I used Castrol European Multi Vehicle Fluid (I am not sure they make that or call it that anymore) and I am fairly certain I filled it to the right level, including the temperature check. Again, I do not believe the hum is directly connected to the fluid change, since I think I would have heard it on the check ride when I was listening very carefulley, but you never know...

The basic design of the XJ goes back decades. They have always been susceptible to any tire noise and any imbalance in the wheels -- same goes with the rear differential. The rears do tend to make some noise and any degradation in the mounts will make it worse .... or sometimes noticeable.

I remember many many problems when the car had inboard rear brakes -- lots of differential noises that were actually defects in the mounts.

While the TC could certainly have an issue in a particular car -- it does not seem to come into play with this issue.

To say the hum is not related to the TC lockup itself is not to say it does not come into play. XJRJEff's contention was that the lockup may make some other effect more pronounced. There is just too much coincidence to ignore that the problem occurs at almost exactly the lockup speed, AND is affected by S mode, which is reported to change the lockup point. Yes, there are flyers (which are almost certainly not the same issue), but a number of posters report the issue shows between 52 and 55 mph.

Your hum may be the beginnings of gearbox fault or failure. Jaguar dealers say sealed for life gearbox but gearbox manufacturer says change gearbox oil and filter at 60K and then every 30K. Also advise replacing oil pipes. I flushed with a gearbox flush instead both at 60 & 90K miles. VERY important to replace gearbox oil with correct spec. Also you will require gearbox sump gasket and I would recommend replacing all O'Rings that you disturb. Gearbox oil change manual and gearbox repair step by step manuals can be found online. Also when refilling oil jack car up so rear wheels can turn. Fill with oil until oil dribbles out of Allen key plug at rear right hand side of gearbox, replace plug, start car and run engine. Change through all gears and get oil temperature up to 50 degrees centigrade. I think this was correct temp. It is listed in the gearbox oil change manual. With correct temp and gearbox still turning remove the same plug and continue to fill with oil until it once again dribbles with oil again then replace plug and tighten to specified torque setting, not forgetting to place a new O'Ring in first. I've replaced a couple these gearboxes now for others who didn't know about ZF's recommendation as opposed to Jaguars. I've also serviced a few gearboxes at correct intervals and I know of two that have now done over 200k with no problems. Servicing gearboxes is a damn sight cheaper than a reconditioned box let alone new ones. Shop around for the gearbox oil. BMW dealers prices are one place that is cheaper than Jaguar but dedicated oil suppliers can be a lot cheaper but may sell only at higher volume, (eg. 20litres) which will nearly do 3 gearboxes.

Humming at 45-48 mph
 

1998 Vanden Plas with 135,000 miles has aa humming noise and vibration at 45-48 mph then goes away. Had three wheel bearing replaced, new tires and car aligned but still hear the humming. I purchased a used drive shaft online and had it installed but still no luck. I tried testing the temp of the differential housing after a long drive to find the right side is running 12-14 degrees hotter than the left side at the output shafts. Is this difference telling me the bearing is bad on the right side?
Tony

Bearing Drive Train Noise
 

As the last poster stated the temp difference is a indication of bearing wear. These symptoms were present in the following situation:

• Changed out the FR bearing [steering]
  • Circlips and internal bearings
    • corrosion and water infiltration
• Drove vehicle for a week before changing FL bearing
  • Noticeable temp difference
  • Changed out the bearing
• Both are now running warm..not hot
• All is as it should be

I suggest your symptoms would indicate bearing wear. Additionally almost all bearings on the XJ's will experience water infiltration creating wear and deterioration of the bearings themselves.

I will be changing out the rear bearings shortly. Good luck with yours.

I have a noise starting at 35 mph and goes away at 50. It will also go away if I hit the gas or let off. I also have the humming at around 52 mph. The humming doesn't bother me but I would like to know what the other is.

noise
 

Athe End anyone had found a solution for the 52-55 mph TC locked noise? Have the same problem too!


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