I tackled transmission valve body cleaning yesterday. It was fairly straightforward and with the many, many, many, many helpful posts on various BMW forums about the 4HP22 and 4HP24, there were tons of pictures to follow along. I must say my valve body was in MUCH better condition than those I saw on the BMW forums. I’ve heard Jaguar’s version of the 4HP22/24 use stronger clutch material. BMW uses the 24 for the 5.0L V12, we have it in our 4.0L I6 so that should be some indicator of Jaguar’s attempt to provide longevity.

Removal was straightforward. About 13 T27 bolts to separate the valve body from the case. I used an old brake pad box with holes punched in it to keep track of the differing length bolts. The electrical harness is secured with a 30mm nut. I picked up a socket because it’s also the same as the drain plug for the engine oil sump. Ive been getting by with an imperial sized socket for oil changes.




Because my transmission has had fluid services very regularly, the ATF was bright red and clean. I was hoping to find gunk somewhere in the valve body to explain my clunky shifting.

I didn’t find much. I cleaned and checked all four solenoids. The only one with a mesh screen was the pressure control solenoid, and it was very clean.



I removed the smaller valve block assemblies for each solenoid, and apart from some slight traces of grey in the red fluid, not much else to write home about.




Everything was thoroughly cleaned with brake cleaner. I ended up using 4 cans total. I did not split the valve block open for a deep cleaning because I was worried about losing cups and check ball and whether the gasket could be reused. I may dig into it again some day with a better workspace to organize things. I did take the two accessible end plates off, and cleaned the springs, pistons and bores. No broken pieces or residue anywhere.

All in all, I ended up replacing roughly 7 quarts of ATF.

The transmission is shifting significantly smoother overall. I don’t have the very annoying 2-1 downshift when coming to a stop. That was very clunky before. Lockup is happening correctly at about 52mph, and is smooth, which is how it was before. 1-2 shifts are noticeably smoother as well, as are 2-3. 3-4 is where I’m still having some harsh shifting. Still a good improvement overall.

The only thing that I can see out of spec is the resistance of the pressure control solenoid, MV-5. The resistance was 6.7 ohms. Specs for it are 4.5.- 6.5 ohms. I’m not sure if that could be a contributor to harsh shifts. What do you guys think?

Nick

 

Hi Nick,

Good job on the valve body and thank you for sharing the photos!

I assume that after our discussions in another thread that you used a fluid other than Dex VI as your new fluid? I thought I recalled that the transmission fluid capacity was closer to 10 quarts than 7, so you may still have some old Dex VI mixed in.

Have you looked at the electronic side of transmission performance? If I recall correctly, smooth gear shifts depend on the ECM and TCM working together based on several sensor inputs, including the CPS, MAF sensor, TPS, the road speed signal from the ABS Module, and possibly one or more other sensors such as the CTS. All of these can be affected by loose or corroded electrical connectors and ground points.

That reminds me, did you get your ABS wheel speed sensor harness repaired?