OK, so took the Sovereign to Jiffy Lube for tranny fluid change out (shifting roughly).

They changed fluid, but not the filter, saying it (the filter) looked too complicated, and they didn't want to botch-up something. It did shift a little smoother, but not quite where it should be in my opinion.

Shouldn't these filters be changed? Are they permanent and cleanable for use again? I don't have the time to do this myself. I'm a little miffed that Jiffy was clueless...

 

Hello JAGBRO, for my part I do the emptying of the automatic box, myself, it is simple, it does not require much tooling. Below you will find the maintenance schedule. The box oil and the filter must Be changed at each emptying, this guarantees a long life to this organ.

cordially

 

Is the filter difficult to change out? What was Jiffy baffled about?...

 

No, it is not complicated to change the filter, find here attached, the detailed procedure for the drain.

Cordially

 

Hi Jagbro,

Did the guys at Jiffy actually remove the transmission pan or did they just drain the fluid and refill?

The filter is just secured by a few screws and just pulls straight down. Nothing to it. Maybe they couldn't source a new filter quickly and gave up?

Regarding your rough shifting, if they only did a drain-and-refill, then more than half the fluid in your transmission is old, because that's how much remains in the torque converter and passages in the valve body and other areas of the gearbox. This means you either need to do at least three drain-and-refill procedures to remove as much old fluid as possible, or a true flush via the cooler lines to remove all of it.

The original fluid specification for your car was Dexron II or Dexron III. Those fluids had significantly higher viscosities than the modern fluids that replaced them (Dexron VI and Dex/Merc). The only two fluids I know of that have a suitable viscosity for the XJ40 transmissions are Redline Oil D4 ATF and Mobil 1 ATF.

Also, smooth gearshifts depend on good communication between the ECM and TCM and good sensor inputs for engine load (MAF), road speed (ABS Module and wheel speed sensors), ignition timing (CPS) throttle position (TPS), etc. Of these, the two you can affect most directly are the MAF (clean it with MAF Sensor cleaning spray) and the TPS (clean its electrical connector, drill drain holes in its plastic case and flush it out, and adjust any slack in your throttle cable). I have photos on some of these topics at the link in my signature.

Cheers,

Don

 

Cool. Yea, they claim to have removed the pan, and were intimidated when viewing the filter.

So that's good info. It does shift a lot smoother now, much improved- especially 1st to 3rd gear from a rolling stop. It's mainly the overdrive that kicks in at 55mph (English), with a bit of a thud. There's is no question that the MAF and Throttle Body needs to be cleaned. I need to stop putting this off... Thanks Don.

 

Hey Jagbro,
No offense, but it IS Jiffy Lube after all. Oil change? sure, no prob. Trans fluid.. mmmm Not so much. I get not having time to do it, but I'd take it to a shop for that.

 

There are 2 different filters that fit the 4HP24. The sedans have a deeper pan and require the short extension to reach the pan bottom for proper fluid 'pick-up'.




The XJ-S 4.0 has a shallow pan and uses the flat filter.



Maybe they were confused about the application.

It is a fine mesh screen and can be washed clean.
Replace if damaged.

bob

 

The only thing I would add is that you do need a new sealing O ring part number JLM2127.
New O rings are usually provided with the filter kit, though they are occasioanlly missing so Jaguar proves the O ring separately. An oil and filter change on this A/T is the easiest I've ever done

 

There appears to be some type of linkage along the driver's side of the pan. This need to be disconnected?

 

That's the cable that connects the gear shift lever at the J-gate to the gear selector lever and rotary switch on the side of the gearbox. I don't think you have to disconnect the rotary switch, but it may help to remove the steel debris shield, which is secured by a couple of 10mm screws.

You will need to disconnect the dipstick tube from the front end of the sump, and it helps to loosen or the screw that fixes the upper end of the tube to its mounting bracket so you can push the tube out of the way or temporarily remove it.

Cheers,

Don