HI, I have a 2005 XK8 Carbon Fiber Edition convertible with about 67K mi and I am concerned there may be a slight trans problem. Not all the time, but every once in awhile after starting from a stop sign or traffic light, there is a slight hesitation from the trans after stepping on the gas pedal. It's momentary but a noticeable delay in catching.

Any thoughts......... maybe it's nothing to worry about.

Ron

 

I experience the same problem on my 03 XKR. I haven`t done anything about it yet but it makes me wonder also if I have an impending transmission problem.
Craig

 

I took a 7000 mile trip in my 2003 XK8 this past summer. We drove through lots of mountains out west and I really taxed the transmission both uphill and downhill. Towards the end of the trip I was occasionally noticing a symptom like yours. I also had the "bark" between hard shifts that is apparently caused by the lack of a certain additive in the transmission fluid. A few weeks ago I finally got around to adding the additive, and I made sure the transmission fluid was at the correct level at that time. It was apparently about half a liter low because that's how much transmission fluid I had left over after draining out a liter of the transmission fluid to add the additive.

Anyway... Since I added the additive I haven't had the problem with the jerky starts. I think it was happening because the transmission fluid was a little low. The additive is just supposed to cure the "bark" sound between hard shifts (that problem has gradually faded, BTW). I know this sounds weird, but I don't have any leaks in my transmission. The floor in my garage has not shown any signs of leaking fluid and the underside of the transmission doesn't show any signs of leakage. I don't know where the fluid went. Maybe it just evaporated or something. I did some really hard driving in the Rocky Mountains. I drove to the top of Pike's Peak and back down, using the transmission for braking most of the way down. Maybe over time minuscule amounts of fluid seep out from somewhere. Whatever caused it, topping off the fluid fixed the problem.

One last thing, just so that it's clear what kind of problem I was having, every once in a while I'd roll up to a stop light and wait for the light to change. When the light turned green I would step on the gas and the engine would start to rev slightly, then the transmission would suddenly catch and there would be a slight jolt through the car. After that slight jolt everything seemed fine and the car shifted with no problems. This might happen once on a 30 mile drive with 15 stoplights. Also, and even less frequently, as I would be slowing down for a stoplight the transmission would seem to linger in the higher gear and then suddenly downshift.

 

OK.... Thanks. I thought that the trans on an 2005 XK8 was sealed and fluid levels were not able to be checked.........?? I don't have any "bark" issues, except with my dogs of course....

Ron

 

Sam...did you do this yourself without a lift? If so, where did you buy the additive and did you change the trans fluid or just top it off? Did you top it off with trans fluid and if so what fluid did you use. I`m in South Carolina BTW and I have the exact same trans symptoms your car had. I`ve got an 03 XKR. Thanks...
Craig

 

I got the ZF additive at the Jag dealership. It listed for $50 something, but the guy in the parts department only charged me about $45. Make sure you get a liter of the ADDITIVE and not just a liter of the ZF transmission fluid. I think the new ZF fluid has the correct amount of additive already in it, so if you do a complete fluid change you can just buy the fluid, but if you've got the "bark" you need to put the additive in it.

I did it without a lift. I drove it up on some ramps and then jacked up the back end to put it on jack stands. You have to get the car level to get the fluid level correct.

I just topped it off. First I drained a liter of the existing fluid, then I added a liter of the additive. Then I added in the fluid I had previously drained until it got to the correct level. It's all done from below, so you need to get a little hand pump with hoses to pump the fluid up into the transmission. I got one at Harbor Freight for about $8.

The hardest part was removing and reinstalling the filler plug. It's on the side of the transmission and it's blocked by the exhaust pipe. It takes an 8mm hex wrench (like an allen key). An allen key is too big to fit it, though. I mean, the hex part fits in the hole in the plug, but the wrench is too big to be maneuvered in the tight space between the plug and the exhaust pipe. I bought a set of hex head sockets at Harbor Freight, and I slit the socket through an 8mm box-end wrench. Then I wrapped my hand around the other side of the exhaust pipe to help guide the wrench/socket combo into the filler plug. I had to add a cheater bar onto the end of the wrench to get enough torque to loosen the plug. As soon as you remove the plug the fluid is going to start pouring out, so make sure you have a big pan under the filler hole.

When putting fluid back in, the car has to be running and the transmission has to be in gear. That's why you want to have the back end on jack stands and the front end on the ramps. You don't want the car driving down the ramp and off of the jack stands. You'll also need to wear gloves because the exhaust starts to get hot. You have to shift it between the gears to make sure the fluid is all through the transmission. Once the engine is running and the transmission has been shifted through the gears you can use the hand pump to pump the fluid back in. There's a TSB somewhere that explains the procedure.

 

Thanks "Samwise"!! I`ve got to do this soon or have it done for me. Appreciate the info...

 

Oh yeah, one more tip: After you've loosened the filler plug, switch to one of those box-end wrenches with the built in ratchet mechanism. That way you don't have to keep taking the 8mm hex head out of the filler plug to keep twisting it out. I started off trying to break the filler plug loose with the ratchet wrench. Unfortunately I broke the ratchet mechanism in my wrench while trying to break the plug loose. Then I switched to a regular wrench to break it loose, and I found that a 5/16ths inch wrench is about the same as 8mm, so I was about to use that box-end ratchet wrench to remove and reinstall the plug.

 

first thing I thought when I heard your symptoms is the Lurch...google that, there's an entire website devoted to it. It can be varying degrees of frequency and jump, but it is a very common behavior for the ZF 6HP26, many models (XJ, S-type, xks) have the bump. You could try doing a hard reset to clear the TCM, it sometimes cures that problem. my car has it, always has...I use the sport button and it never happens. Also, check with the dealer, there may be a reflash for the transmission that corrects that downshift point where this most often occurs. Worse case, completely stop at all lights and stop signs, that will eliminate much of the transition. BTW, I have had my fluid in my transmission changed by the dealer, and before and after the service, I have had some amount of this lurch.

 

Sam...maybe a dumb question but where did you position your floor jack to raise the rear end and where did you place the jack stands at the rear. I don`t want to mess up and jack in the wrong place...thanks..
Craig