Hello all.
I've decided on a change. Im going to be selling my 2003 XJ6 sport and buying a 2004 XK8. I'm going to see a car tommorrow that looks very nice. Its clean, has a full service history (jaguar history up to 2018), and only minor bubbling on the rear arches, and its covered 127000 miles.
The owner (for 4 years) has no evidence of the gearbox being serviced, so we can probably asume its never had one. Im told the box shifts very smoothly.

My question is, is buying an XK8 that hasnt had a gearbox service a no-no or should a decision be made on the test drive ? (and then if purchased service the gearbox right away).

Im aware of the 'should you, shouldnt you' service a sealed for life box. My current XJ6 has 137000 miles and the box has been serviced twice. (its still developed some clunkiness recently but thats another story.....

many thanks, Nerf.

 

General wisdom is change the ATF every 50k. Seems like cheap insurance. That said, the 6 speed in the second generation XK8's is pretty durable. The fact that it shifts smoothly is a good sign. Besides my XK8, also have a Lexus LS430. Same "sealed for life" unit (and no dipstick). I changed it at 100k and shifts felt smoother. Full service (and partial at Jaguar) is great. Personally, I'd have it serviced immediately. Good luck w/ your purchase. Hope it goes well.

 

My personal opinion would be based on a test drive, and how much im willing/able to spend/do on it myself. Having the trans serviced is a common thing, and i dont know if id completely disregard a car just because it hasnt possibly been serviced properly. There again, i wouldn't put one above another just because of service. A car is a mechanical device and any car, especially used "exotics" with lots of sensors, can fail at any time for seemingly no reason. Or they could go to 300k miles without a hiccup. Just my two cents

 

Fresh ATF in these cars is always a good idea. My wife's 2006 XK8 turned 125,000 miles this past Friday morning. We have done 4 ATF refreshes during the nearly 11 years we have owned it (one pan drop / sleeve change using ZF Lifeguard 6 ATF and then three simple drain-and-fills using Motorcraft Mercon SP ATF). Her ZF 6HP26 continues to perform exactly as designed, and I believe our relatively frequent ATF refreshes is a big reason why....

127,000 miles on the factory fill of ATF is asking for trouble. The friction modifiers in all ATFs wear out over time and heat cycles. Personally, I would not consider acquiring that car. Your opinion may vary....

 

Mine shifted fine but had a rattle when cold echoed from a nearby brick wall....I drained 3.6 litre and refilled with 6 litre !
So buy it and change the fluid and filter . In uk a genuine german filter is about £20 and the fluid about £30 ..look on ebay
You will not be happy until its changed !
Read my list on XJS owner looking for XK8 a little lower down ..in UK its all about the rust.

 

^^
I would also be more concerned about potential rust issues. What presents as "minor bubbling on the rear arches" could mean more is hidden. Check the rear chassis legs where they drop to meet the rear suspension A-frame mountings, and the floor pans under where your feet would rest.

If it's a UK car, then you can dial the registration # into here:
https://www.check-mot.service.gov.uk/

to get some idea of its MOT history.

If the car checks out OK, then put the trans filter/fluid change on your list together with all the other fluids, so you establish a base line.

Good luck!

 

thanks so much for your replies, its always good to get fresh thoughts, especially when your own head is filled with the possibility of a new car!
i checked the gov/mot site and there are no advisories for rust at all. And i'm currently watching youtube vids on the rust spots so im reasonably up to speed on that front...

 

The idea of a "lubricated for life" transmission is total BS. The life of the fluid ends at the same time the transmission does. So, give it more life. If it has been changed then you won't hurt anything and you'll know where you stand. It will only do it good. Many threads here on the forum on the subject and how to do it. TM

 

I would say unless you are good with the spanners dont buy it ..finding people to work on it is expensive and they are difficult to fined

 

Since I'm just over 100,000 miles with no transmission problems and never serviced, I'm going to plan to replace the fluid in the summer of 2023.
Based on the temperature requirements for proper service, I figure that I can simply drain and refill when the outside air temperature is above 90 degrees F.
No need to warm up the transmission because everything is already at the proper temperature. No burned hands.
This makes perfect sense to me but I don't think I've ever seen anyone suggest this.
Is my logic sound or am I missing something?

 

90 degrees is well below the recommended pan temperature range for the procedure. If I remember correctly, the target temperature of the pan is 120 to 125 degrees....

 

Maybe 30-50 C? So 90 F is okay.

 

Hi Nerf,

At 127,000 miles, the transmission is well overdue for a service. But if it really does shift smoothly, it should respond well to the proper treatment, which at this mileage means dropping the Mechatronic/valve body to replace the bridge seal and tubular seals, replacing the pan/filter and electrical connector sleeve, and replacing all the fluid. That version of the 6HP26 probably has the early style pan screws that are prone to stripping of the small Torx socket in the heads, so I would recommend also replacing all the screws with the updated T40 screws. I just did all of this on an '06 today (at just 53K miles). This later car came with the T40 screws, but they were well rusted, so I replaced them all.

It also helps to have the transmission adaptations cleared so the TCM can more quickly learn your driving style and adapt to the friction/slippage characteristics of the new fluid. Many high-end scan tools can clear the adaptations.

Also, on an '04, there may be a 2005 firmware update available, but you'll need a knowledgeable shop with SDD to check for that and update if available.

The fluid fill temperature for the 6HP26 is 40°C / 104°F, so not particularly hot. The fill plug is opened at 30°C / 86°F and the fluid allowed to drip out. When the temp reaches 40°C / 104°F and the fluid is just trickling out, the fill plug is reinstalled. If the fluid exceeds 50°C / 122°F, the remaining fluid level will be too low. When the fluid reaches 40°C / 104°F, the exhaust pipe is just getting too warm to comfortably touch, so find the best way to position your hand to reinstall the fill plug before it gets that warm.

The fluid temperature cannot be accurately measured on the plastic pan because plastic is a poor conductor of heat, so it must be measured either with an infrared thermometer aimed at the fluid dripping out (if a sight line is available), a temperature probe on an oscilloscope or multimeter, or via Live Data with a scan tool or SDD. I use Live Data on an Autel MaxiSys Elite because it is much faster and easier than SDD.

All that to say, I tend to agree with Mike that the rust would be more concerning to me than the transmission.

Cheers,

Don

 

Some very good advice from Don B. I have just carried out the work he advises on my 2005 XK8 at 116000 miles. It made quite a difference. One area that my opinion differs is on the adaption reset. If the gearbox is working smoothly before you carry out the change I would not reset the adaptions. I came to this conclusion after getting two quotes from ZF specialists in the UK and reading a lot of ZF source data. Both the specialists advised they only reset the adaptions after oil filter and seal changes in the event the gearbox is not performing well on a test drive. There is an awful lot of conflicting information on adaption resets. The gearbox is always learning. I elected to drive 150 miles slowly building up the engine revs as I went. I fully respect other opinions may vary on this but for me I elected not to do the adaption reset. I also elected to check the level twice after the component and fluid changes. The first after the initial fill and the second time 24 hours later after the gearbox had completely cooled. I needed another litre on the second check.
Additionally I used the same method on my S type R this also took an additional litre after the 24 hour cool down. So far so good on both.
Fingers crossed.

 

Hi Gas turbine!

Thanks for your kind words and helpful thoughts.

Since ZF and the automakers that used the 6HP26 claimed it was "Filled for life," the various manufacturers' workshop manuals are not overflowing with helpful details for servicing these units. And for many services, the ZF literature refers technicians to the auto manufacturers' procedures, which often do not exist! So we are all left to form our own best judgements based on the available information, so I can't argue with your logic.

The Mechatronic adapts for driving style, but over time it also adapts for the changing viscosity and friction/slippage characteristics of the fluid as it ages. At some point, the adaptations reach their limits and can do no more to maintain or improve shift quality. Resetting the adaptations simply returns the Mechatronic to its baseline so it can adapt to the characteristics of the new fluid more quickly. I have serviced a lot of 6HP26 transmissions in Jaguars, BMWs, Land Rovers, Fords and a Hyundai Genesis, and have almost always reset the adaptations if that procedure was available in the manufacturer's diagnostic tools. After resetting the adaptations, the transmissions may give a few mild hiccups while relearning, but within one or two drive cycles they are shifting better than they have in years. The risk of an adaptations reset bringing any harm to the transmission is very low, unless one drives foolishly during the relearn period.

In Jaguars, one can speed up the adaptation process by performing an adaptation drive cycle procedure in IDS/SDD. But it usually takes at least an hour and involves driving the car while monitoring a laptop display, so I rarely bother to do it. Simply driving the car normally with no aggressive acceleration or wide open throttle will get the job done in no time. So far, every owner has been thrilled with the results.

In cars built before the firmware update in 2005, it is prudent to use IDS/SDD to see if the update is applicable and if so, to clear the adaptations and perform the update, but only after doing one's homework and following Jaguar's procedure to the letter. This includes the use of a 50-amp power maintainer on the vehicle battery, keeping the laptop plugged in to its power supply, and using only an approved interface such as a Ford VCM or genuine Drew Technologies Mongoose. Using a clone device is asking for trouble (although I did my first couple of updates with a Mongoose clone - they took a very long time but eventually completed - perform at your own risk).

Your experience with fluid level is curious! Are you following the ZF procedure for setting the fluid level? How are you measuring fluid temperature? I can't think of any reason the fluid level should be a full liter too low unless the fluid temperature was allowed to exceed 50°C / 122°F during the fill process. Do you have a theory as to what may have caused your difference in fluid levels?

Cheers,

Don

 

My wife complained of rough upshifts in her 2006 XK8 in the summer of 2013 and again in the spring of 2016. In both cases, having the Jaguar dealership in Greensboro perform the Adaptations Drive Cycle procedure using their IDS laptop resolved those issues. Now at just over 125,000 miles, her ZF 6HP26 continues to perform as designed. We have done a total of 4 ATF refreshes since acquiring the car in early February 2012, initially with ZF Lifeguard 6, and the last three with Mercon SP....

Alas, Jaguar Greensboro can no longer perform the Adaptations Drive Cycle procedure because they no longer have the hardware / software required to do it....

 

Hi Don
Yes I followed the ZF procedure to the letter. Did not exceed 50deg C. I also measured the temperature using the boxes own temperature sensor.
I do have a theory, I think the oil becomes aerated as you pump it in. I used an electric pump and a home manufactured rig for filling. I never use external repair agencies. With the gearbox fluid change I did get two quotes. I do not feel it fair to share who from but both were very experienced with ZF gearboxes they are well known in the UK. They both said they would need the car overnight as they always recheck the gearbox oil level from cold after the initial fill. They both stated independently that they usually have to top it up on the second fill as per my experience. I also followed their advice on not resetting the adaptions.
I did it myself as both the repairers were a long way from me and would have required me to overnight in a hotel. I did not save much money on the process by tackling it myself.
I am not a car expert.
I was however an aeronautical engineer for 42 years and spent several years working on the design and development of aero engine oil and transmission systems. For most of my career I was dealing with faults in enhanced computerised control and monitoring systems. I might have applied a little bit of my own experience.
As with most things how you approach these issues is purely philosophical There are never any right or wrong answers just what works for you.
Kind rgds
Gas Turbine

 

Hi Gas Turbine,

Your theory seems plausible. It also seems possible that the professional transmission shops are using electric pumps to refill the transmissions. Flud aeration seems like a very bad thing in a hydraulic device that depends on the incompressibility of the fluid....

Do you notice any unusual noises from your transmission right after it is refilled with new fluid that could suggest air pockets or insufficient internal pressures?

Cheers,

Don

 

excellent advice, thankyou Don!

 

To my knowledge, things are simpler.

The adaptation re-set procedure _is_ the "learning" the transmission does. There is the initial guided procedure (smooth accelerations from narrow speed ranges) followed by 100 miles where the TCM keeps adapting/learning. Outside of that window, the TCM just executes the set transitions from gear-to-gear. The reason the transmission gets rougher with time is because the fluid itself ages and no longer behaves as it did when the adaptations were set.

From what others have shared after talking to the experts at ZF technical support, the time to re-set the adaptations is after a (double) fluid change. This is if you feel the shifting is not as smooth as it once was. The argument against re-setting the adaptations is that the procedure involves intentionally slipping the clutches, which accelerates wear. In a simplistic way, just replacing the fluid should bring the transmission to the same state as when the adaptations were last set, so no re-set of the adaptations should be necessary. In the real world, the clutches have worn, the fluid brand/formula could have changed, the car could be operated in a different climate, etc., making the procedure desirable.