i have a 2000 jaguar xj8 that seems to be stuck in 4th gear. it goes in reverse fine but when you put it in drive it revs up to about 2000 rpm and then jerks reak hard and drives off very slow. it also says gearbox fault when the car jerks. i scaned it and got the following codes 1646,1647,0706,1722,1000. is this something inside the transmission or something with a computer?

 

yah, seen some of those codes before, when doing your research, consider looking in the XK8- XKR area also, as the transmissions and engines were identical for several years. R versions excluded, of course.

Search for P1646

Search for P1647

Search for P1722

 

Same problem/codes with mine last year... sorry, required a rebuild - 'A' drum broken along with several other issues.

 

What other issues did you have? Did you do the repair yourself or take it somewhere?

 

Had it repaired by a local transmission shop that happened to have a guy who specialized in Jags. Other issues were valve body related - several valve body pistons had worn into their respective aluminum cylinders (a common problem, I was told). All were replaced, cylinders sleeved with brass and they replaced any other hard parts that showed any wear. Total cost was about $3500.

 

Hi Bimmer3
Just read your issue regarding the transmission, my 1998 xj8 200k's has just done the exact same thing, and you have asked the axact same questions i have. what responses did you get and have you sorted the problem?
Regards
John

 

I've been doing some research on this from a bunch of websites and I'm almost 100 percent sure it's the a drum. I'm still looking around at different websites just to see if there's anything new but I think I'm going to pull the transmission when I get a chance and have a look at the a drum and see if I can fix it.

 

I am almost reluctant to offer this sollution, but once again, it could be electrical. One time after replacing my battery, the transmission was acting really odd. when slowing down to come to a stop at a light, the transmission would clunk really badly, always at the same speed. I disconnected the battery again, fully charged it, held the negative lead to the positive terminal (with the positive terminal connected --a "hard reset" of the computer), reconnected the battery and never had the problem again. Every time I have a problem with my Jag, the first thing I do is do a "hard reset" of the computer to see if that solves the problem. It has solved many ills.

 

Had the problem about a year and a half ago and sorry to say it requires a rebuild.
Dan

 

I tried the hard reset and it still has the same problem. I'm going to pull it out when I get a chance and look around see if it's the a drum. If anyone has any tips or pointers about working with these transmissions let me know.

 

the xk8/R FAQ thread has some 5hp transmission documents that may help you. Go down to 'transmission' to find them

 

I own a 2000 xj8. The transmission A drum failed a common thing I was told. I had a local transmission shop overhaul with updated A+B drums. It shifts fine but now chatters in the morning when cold and has a humming noise at 50 to 55 mph in drive mode. But when shift to sport mode goes away. Transmission place says transmission is fine and is very common problem with no repair fixes. Can anyone help me? Thanks

 

Chris,
there's a whole thread dedicated to the transmission hum from 50-55mph in normal mode.

https://www.jaguarforums.com/forum/s...ight=vibration

To be honest, I'm quite reassured by your post as your transmission shop is the first authoritative source to say its "normal" and not a sign of impending doom.

 

Help.. I have a 2000 xj8 128000 miles.. when in reverse it feels like slipping clutch, car moves off very slowly, however all is normal in drive. Any ideas or is it time to get rid, the car itself is only worth £2000. Thanks

 

that sounds like the main control valve issue, which leads to A drum failure. It will eventually lead to a failed gearbox and display 'gearbox fault'.

It can be fixed with a valve block rebuild, the choice is yours....talk to a transmission specialist on prices for this fix. With a knackered trans it's worth 400 quid....

 

P1646 & P1647 are the failure codes for the heater elements on the upstream O2 sensors-they burn out after high mileage & throw up the engine check light. The engine ECU adopts a 'basic' fuelling map & fuel consumption goes up by around 15%.

P0706 & P1722 are transmission fault codes & consistent with the fault symptoms you are getting.

P1000 is not an actual fault code & simply means the system has not yet completed it's 'drive cycle' tests satisfactorily-which it can't do now with the other fault codes you've got.

Regarding the transmission, the first thing to do is get the valve block checked-it's not that hard to remove & doesn't require a complete transmission removal. There's plenty of information on this forum about this issue, which is really starting to rear it's ugly head now with numerous posts about 'A' drum failure now appearing

Get the valve block checked first-if that doesn't cure the fault then it looks like the dreaded 'A' drum failure, which will require a transmision removal & overhaul.

 

Thanks for the info. Just joined today and was about to ask about the same problem. I have a 2001 xj8 with 107,230 miles.

 

Hi, my '98 XJR is garaged and occasionally driven, recently we replaced the battery and now the car literally acts like it can't get out of first. I read somewhere that it might be a safety "reaction" by the car, as if it were reacting to being stolen. Is there any truth to this? Is there a way to fix it on my own? I live in a rural area and my mechanic is a 3 hour two ride away.

 

Try moving the gear selector to "4". If the transmission shifts normally after doing that (except for going into fifth gear obviously), you might have a stretched shift cable.

 

My 1998 XJ8 trans went bad a few months ago. I elected to buy a used one. The first day it acted as though it was taking to long to go in gear.. The second I put in Reverse and it clunked. Put it in Drive and the motor started to rev a bit more than normal to pull out, then it was like I was hit in the rear buy a car doing 5mph. If I put it into gear this third day it hunts for Drive and slowly (about 3 sec) then a small clunk. I could pretty well say that if I didn't ease into it it would thump pretty solid. I read in this section where the Trans sometimes needs a bit of time getting used to the new fluid that was put in upon replacement...what say ye?