Wheel bearing problem
 

Good morning
it's been a while since I have been on here, and first time with my recent purchase 2006 2 litre diesel x type.
Bit of a strange problem with this, I bought the car a couple of weeks back, it looked ok in the pictures, relatively recent MOT 92000 miles on the clock.
I bought it in London had a relatively problem free drive back to great yarmouth until the outskirts of town.
started hearing and feeling lumping coming from front passenger wheel area.
Just about got it home, on getting it checked the next day I'm told the wheel bearing has shattered.
the wheel bearing was replaced, with I'm not 100% sure but not an OEM part.
All seemed fine for a couple of days, then same problem came back. It appears this new bearing had come loose the mechanic guy could make no sense of it and tightened it again.
He assures me the threads are fine, but hey Presto a few days later it comes loose again.

This has got everyone baffled, has anyone come across this problem before and can throw any light on this.
thanks guys any help greatly appreciated.

Ok, going to ask the silly question, did they stake the nut to prevent it from loosening? Yes, there is a spot where you are supposed to bend a part of the bearing nut to prevent it from loosening. If they did that and the bearing is coming loose, they either: 1) did not push the bearing al the way on and now the wheel is sliding into the correct position, or 2), the nut is slipping over the threads and the threads are not ok because a nut should not be able to slip over the threads.

I would also ask them what they torqued the nut to. Should be 175 ft-lbs as I recall. If they did that, bad threads and the wheel not being in the proper place would be obvious. Someone is lying to you. Just not sure what they are lying about.

If you want to do a simple check yourself, get yourself a decent size torque wrench and a 32mm socket (as I recall). You can pop the cap off of the center of the wheel. Look inside and you should see a collar extending towards you from the nut. Is it making a perfect circle. If yes, then they didn't stake the nut. if it is oblonged, then they stakes the nut. Assuming that it isn't staked, you can slide the nut into the center of the rim and get it on to the nut. You can then take the nut in the tighten direction. If you turn the nut with next to no resistance, then the nut had backed off of the bearing (ie, the staking would have prevented this). If you turn the nut and you get up to say 100 ft-lbs (value is not important) and you feel it suddenly get looser as you are tightening it, then odds are you are looking at a bad thread condition. If you get up to some torque and it seems to stay there and you are tightening and tightening, then odds are the bearing was not installed all the way and you are pushing it into place using the nut.

I would also say to move the car forward and backwards a few feet/meters and then do this again. Since the tires are on the ground, if there is any significant movement in he nut, there should be movement in the tire and you may find that after moving car, you may get a little more movement. Just make sure that if you do this and you have moved the nut, remove the tire and then using a punch and a hammer, oblong the nut using that collar.

Hi Thermo
Thanks very much for the rapid reply and a detailed explanation, unfortunately none of that means nothing to me but I am taking the car back tomorrow with your printed explanation and hope he can put things right.
To be honest I have no knowledge whatsoever of the process behind changing wheel bearings but I have done a bit of reading up recently.
Could the nut that came with the new bearing kit be bad or somehow responsible for it coming loose? I will be honest and say this is the first time I have used this mechanic, but he came recommended and seems to be knowledgeable.and I am assuming he has done many bearings before, but I will present him with your explanation and see what happens.

Thanks again I will keep you informed of how it goes

Wheel bearing
 

Hi again
I just had a discussion with the mechanic and he assures me this wasn't a staked nut, and apparently some are and some aren't this one isn't.
Since speaking to him I have done some more reading up on it. I have read they have to be tightened with a torque wrench to 200lb and not an impact wrench.
Can I ask how crucial is that as I think it was done up with an impact wrench, I am not 100% sure about that I will have to ask him when I see him.
But just so I can be prepared when I see him if it has been tightened with an impact gun and not a torque wrench how likely is it that it hasn't been tightened correctly.
regards Chris

C2S51676

Take the impact wrench and put it where the sun doesn't shine!! And Never, never, never use one on your X's lug nuts.

Lower ball joints. Tighten the pinch bolts to 69-85 ft. lbs. (93-115 Nm).Outer tie rod ends. Tighten the nuts to 43-58 ft. lbs. (59-78 Nm). Sway bar links. Tighten nuts to 69-85 ft. lbs. (93-115 Nm). Hub retaining nuts. Tighten the hub nuts to 177-199 ft. lbs. (240-270 Nm). Front wheels. Tighten the lug nuts to 65-79 ft. lbs. (88-108 Nm).

https://www.jaguarforum.com/showthread.php?t=35264

prismouk, there are 2 big differences between an impact gun and a torque wrench. The first being in just how they operate and the second is how accurate are they. A torque wrench is just like a normal wrench that you would use and the harder you pull, the more torque that it will apply and it will tell you how high of torque you applied. With this being said, there are 2 kinds of torque wrenches, dial and snap. The dial is pretty obvious, As you apply torque, the dial goes up and tells you how much was applied. The snap type, you set it to a torque and you keep pulling till you feel it snap, then you stop pulling. You are now at that torque.

When it comes to an impact wrench, I liken it to using a big hammer and a wrench with a big flat side to it. You keep smacking the wrench with the hammer till it won't move any more. What did you torque it to? You have no idea. You can get a general idea because most impact wrenches are rated to go to some maximum torque. yes, there are some out there that are adjustable and will supposedly torque to a variable level. But ,this is very subjective and not very accurate.

As for the nut, the mechanic is correct in that not all cars use a staked nut. But those that don't, use some method with a cotter pin to hold the nut in place. So, again, if the nut attempts to back off, the cotter pin prevents the nut from turning. Either way, the nut should not be "loosening on its own" or "able to be tightened more after a little bit of driving". I am curious as to what is the final verdict of "the wheel was loosening up because .......".

Wheel bearing update
 

Hi all and happy New year.
Just an update on this wheel bearing fiasco. Took the car back in this morning had a word with the mechanic.
Firstly he insists it's neither a stake nut or a shaft for a cotter pin. As for torque he said he torqued it last time to the maximum his wrench would go to 250 Nm and I think the proper rating should be 270Nm so I believe he borrowed a wrench from a fellow mechanic and torqued it to the required 270Nm. He said he also put some stuff on the threads, I forget what he called it but I think it was something like thread lock or something like that.

I picked it up an hour ago took it for a run, ok for now but I know if it is to loosen again it will be a couple of days or so.
I will keep you posted
Regards