Your symptoms still point to a valve body problem. You are correct that as the servo bores wear you lose more and more hydraulic fluid but remember that it is designed that way. In other words it's not 100%. Even when brand new there is some leakage past the servo's so it's really a question of how much leakage and when does it start to effect the ability of the transmission to function properly.

I would swap the valve body first. About $350 new or about $180 for a rebuilt unit. See what happens then report back. You could have a combination valve body problem and case bore wear.

See this post for good info on the valve body.
https://www.jaguarforums.com/forum/p...-6-them-67759/

This is a simple explanation of the transmission differences and what problems cause what symptoms.
https://www.thetransmissionshop.com/...rsions-of-5r55
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Just checking in with updated info...

Replaced solenoid pack, NOT the problem, and I guessed as much but it was a conveniently provided unit so no harm no foul...but it right away gave me a different fault P0775 which is basically a gear ratio failure in 1-5 (pressure solenoid "b")...at first I thought the second solenoid pack was faulty so I reinstalled my original and got the same code...

So I pulled the valve body and removed and cleaned each spring and valve piston, found 1 that was broken, unfortunately it is NOT one provided in ANY of the rebuild kits...it is the "Overdrive servo control spring" (item #12 on page 73 ATSG rebuild manual/which is absolutely essential if you decide to work on this yourself)...I did find a few valves sticking and a ripped spot in the gasket (which I have now replaced)...cleaned and polished the valves with a 3m pad cleaned out the valve body and flushed it...

But this spring...nowhere to be found...so I have a new valve body on order should be here in a few days...all over a $3 spring...

I know the overdrive servo does not exactly fall within the diagnostic menu for this but I think it was a combination of small faults,a change in driving environments (moderate weather to extreme temperature swings), lots of miles and a few small bits sticking (by the way the parts sticking were not stainless or carbon based metals they were aluminium and really only one flake...I have been quite surprised at how clean the fluid is in the pan drains...(I have drained and refilled with new fluid 3x now)...

At any rate if I find a replacement spring I will try it out and let you know, until then I will wait for the new valve body...

 

PS...I only ever get 1 code fault...first it was the P0731...now it is the P0775 but no other codes at all...

 

Yes. That's why I always suggest the entire valve body replacement for that transmission. Too many LS guys have swapped solenoid packs with no change. They do go bad but the valve body as you found is the main source of problems.
Strange that the code changed on you to.

If you can let us know when you get it fixed. It sounds like you are almost there. Good job troubleshooting!

I think for a broken spring I would visit a transmission shop and see if they have a junk tranny you could rob parts from.
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Yes I tried that but unfortunately I am in a part of the country that sort of freaks out when you say "Jag" and only mildly nods when you say "Lincoln LS"...went to three major transmission repair places and a few minor ones no one wants to let you take part of a valve body...I did the next best thing and dimension-ed and calc'd the spring itself based on the old part...but knowing the "K" value is a shot in the dark...guessing the temperature/spring/compression values is a gamble...

Lot's of 5r55S/W trannys...no 5r55n's and according to web search very few interchangeable parts...

I DID find a compression spring from one of my soldering clamps, same exact size, "feels" about the same...it's made to handle the heat...I've got a week b4 the new valve body shows up and nothing else to do who knows...a short test run might prove the theories...

Thanks for all the help here...the internet has made us all potentially equals...no more black magic hidden info...no more secrets...

 

Just a test drive update...I installed the spring in the "over drive servo valve" put everything back together, cleaned it a re-primed with new ATF took my time and put everything back together torquing to spec...refilled with fluid and took it for a test drive...

Miracle of miracles everything works perfectly NO FAULT CODES after highway test drive that included overdrive and sudden deceleration, turning town driving ran it for about a half hour drove 30 miles or so...the only thing I noticed was a bit of "flaring" when I punch it to overdrive to pass other cars...but it smooths out nicely, no hard shifts, no delay (I was getting a noticeable hard delay into drive), I am pleased as punch a incredibly grateful to this forum...

The original estimate was $4500.00 from the Jag dealer...then a transmission shop offered to fix it for $200-$1000...ended up being $16.00 for gaskets, a solenoid (which I will return) and about $100 in fluid...oh I also bought a torque wrench on craigslist for $20...

On a side note when I first put the gaskets on I did it exactly the way the old ones were with the label to the outside, BUT...I discovered as I took the valve body off the new gaskets had the name printed on the opposite side...at first I thought I had simply mixed them up, but after closer inspection it turned out the name was actually printed on the wrong side, 'Caveat Emptor...ebay is a great resource if you pay close attention...but assumptions can bite you in the backside if you aren't careful...

Shout out and HUGE thank you to all who offered help here...

 

Good news.
Safe to add Resolved to the thread title?

 

Yes safe to add!

Just a bit of an off thought...apparently the way the system works a fault code is not always specific, the original code was a "gear ratio fault"...the second time I got a single code it was "Solenoid B" fault...both of which might lead you to electrical issues...but it was probably sticky valves and a simple broken spring...

It's a bit of a pain to take off the valve body (removing the bolt that holds the harness to the solenoid is nearly impossible), but it is worth the trouble in the long run...the rest of the transmission might or might not be in good shape but considering this car now has 153k miles it's not a bad idea to dig in a little...

Thanks again for all who helped!

 

Kudos to you....

I always enjoy reading about folks saving substantial money by digging into the problem and discovering the fix themselves rather than paying thousands of dollars to a shop that quite likely will stick them for hours and hours of work and multiple new parts that their car does not need....

Well done. Keep us posted on how your second-chance-at-life transmission continues to perform....