Recently, I started noticing a noise coming from my XJR. It was occurring as I made a right hand turn each day to pull out of my neighborhood on the way to work. It's a standard 90 degree stop, and the speed that I have to accelerate to is 35mph. Anyway, it was a slipping/grinding sound (though grinding is perhaps too severe of a word,) and it only occurred after I pulled out there at that particular intersection. My first thought was the differential, but then I figured that it would make the noise all of the time. After about a week of hearing it a little during my daily commute, which is 4 miles round trip, I started to notice the noise even when accelerating in a straight line. I could actually feel it a bit too. At that point, I was wondering if I had been correct about the diff, but then I started to consider the transmission as being the culprit. The fact that it only did it initially when accelerating out of a corner made me think that perhaps the fluid level was low, which was amplified as the car went around the turn. So, I parked the car a week ago, and borrowed another one from a family member. I read various threads on the forum regarding fluid level, etc., and ordered a dipstick for the Mercedes transmission, and a gallon of approved Pentosin fluid.

Fast forward to yesterday, which was my only day off of work, and I decided to go ahead and test the fluid level. I brought the transmission up to 80 C, which took about an hour and a half of idling in my hot garage (I did not want to drive it.) I did the procedure as laid out in one of the threads, and put the transmission in every gear for a few seconds, and then back again for a few seconds. Much to my disappointment, the fluid appears to be at the correct level. I was really hoping that was going to be the issue. Now, the fluid did not smell burned or anything, but had an old or stale smell to it. I have no idea if it is the original fluid or not. I have owned this car for 7 years now, and prior to me buying it, it seems as though it was always maintained by Jaguar dealerships. I bought it with 90k miles, and it is at around 100,100 miles now. That being said, the fluid is a light brown color, like light coffee or engine oil. I am assuming it was originally red, like the new Pentosin fluid, but I have no idea.

Would it be worth dropping the pan, changing the filter, and adding new fluid? Or is this transmission doomed to fail soon? Thanks in advance for any help. I am definitely suffering the 'curse of 100,000 miles' right now The last 100 miles have been horrible. My car has been 99% reliable up to this point. I hit 100k driving to work one day last month, and that very night, a coil pack failed in my car when I went to leave work. The car was down for a few days while I waited for a new coil to arrive. After I replaced the coil pack, I drove it for a few days more, and the check engine light came on AGAIN. This time it turned out to be an oxygen sensor. And, of course, it's the most difficult one to get to, right in front of the driver/under the coolant reservoir. I've been pulling 60+ hour weeks at work nonstop recently, and I have not had time to get to that one yet. And now this transmission issue pops up. Fun stuff.

 

Might be worth checking the diff anyway? Just lift up the rear end and spin the wheels by hand, checking for any roughness when the wheels spin in opposite directions, check for excess lash, etc

 

The colour you suggest means it's 'gone off'. My XJR trans fluid had turned brown from age, not use. I would think a trans oil service is due.

 

Thank you. I suppose a fluid change is certainly worth a shot, and WAAAAY cheaper than a rebuild. I will need to pick up another gallon of fluid then. As far as the transmission pan gasket and filter go, does our car use a unique pan and filter, or will any 722.6 filter and gasket work?

 

I swapped out some of the fluid this past Sunday. It looked pretty bad, like old engine oil. Some of it was also frothy/bubbly, which I did not expect, because the trans was cold, and I had not run the car in about a week. I think it's safe to say that the fluid has used all of its 9 lives. Anyway, I had 2 gallons of fluid, but I did not have my filter and pan gasket yet. I also decided to order a new set of jack stands, because if I have to lay completely under this very low car, I don't want to use the ratcheting style stands that I currently have (I just don't trust them enough.) So all I did was drain whatever fluid that came out, reinstall the drain plug, add back in the same amount of fluid, then run the car for a few minutes going through each of the gears. I had 2 empty windshield washer fluid bottles, and I placed them side by side, matching up the level of the old fluid and the new fluid that I was putting back in. Very simplistic, but it worked great. I was getting a little under 2.5L each time. So, with the amount of new fluid that I had on hand, I was able to do it 4 times. By the last time that I did it, the fluid was actually starting to look reddish, which was much better than it was in the first place! After that, I ran the car for about an hour to get it up to the right temperature and checked the trans fluid level. I went for a test drive afterwards, and I am happy to report that the noise/slipping is pretty much gone No slipping that I could feel, and there was only a hint of noise. I only did about 5 miles back and forth to the gas station, but it was about the same as my usual round trip to work, where the problem was very noticeable before.

Once my new jackstands arrive, I will drop the pan, replace the filter, and fill it up with some more new fluid

 

All good news, here's hoping you've headed off a future disaster.