Automatic transmission problem

[Katzenfreund]

On my Jag the transmission failed - when accellerating with kickdown suddenly the engine revved up, but almost nothing reached the rear wheels...

I towed the car back home and with 5000 rpm it moved a little and thats how I was at least able to bring it into my workshop.

Anyone got an idea what could be the problem?

I decided to take the engine and transmission out (want to fix the oil leak anyway).
I do have a spare transmission and converter from a S2 XJ6 which I could put in, but if the problem could be fixed, that would of course be preferred.

Do you think it needs a complete rebuild or could it be the converter or ...?

Thanks for sharing your thoughts.

[1954Etype]

It could have been low fluid level (bearing in mind you have an oil leak).

[Katzenfreund]

Thanks 1954Etype.

That may be too easy, but then it would not have failed from one second to another. Something must have broken, because immediately before everything was absolutely fine - nice smooth shifting, kickdown worked, not any issue from the transmission.

The oil leak is rather from the engine rear end (seal never changed so far).

[christopher storey]

The 4.2 workshop manual Section FF.X has a very comprehensive troubleshooting guide ( available here on the knowledge base ) to Borg warner Model 8 . The very first thing to check is whether you have lost both forward and reverse drive . If you still have reverse , then a mechanical breakage is less likely, and it is possible that it is the selector linkage which has become deranged. If you have no engagement at all then the possibilities are wider, but I would check first , while the gearbox is in the car

Fluid Level , Colour, and Smell
All linkages
(Inside the gearbox ) the oil tubes
the valve body
the primary valve
Remember that cleanliness is hugely important with automatic transmission, so clean the box exterior before removing the oil pan and wear clean gloves for each internal operation

[Katzenfreund]

Thank you.

I followed the fault diagnosis and all I can do is the stall speed test, because the engine stalls with both reverse and forward. According to the table ("Engagement: none") it is either A, C, a, c, or d.
A - low fluid level: no
C - Manual linkage incorrectly assembled or adjusted: I will check if it broke or misadjusted due to mechanical failure
a - oil tubes missing or broken: possible
c - valve body screws missing: unlikely, but will check
d - primary valve sticking: possible

So as a result I guess I should take the transmission out and inspect all the items you mentioned and which are listed in the troubleshooting guide.

[christopher storey]

Georg : when you say the engine stalls with either forward or reverse, what exactly are the symptoms?( I ask because this is totally contrary to the initial symptom you described of the revs rising uncontrollably ) . The stall test should show slip in the torque converter to about ( from memory ) 1800 rpm if the car is held against the brakes and full throttle applied . If you engage D1 , L or R and apply throttle against the brakes, what happens ? If the rpm only go up to a certain extent - say between 1500 and 2000 rpm, then you are getting transmission engagement. If the rpm will hardly rise at all, then it is probably an engine lack of power problem

PS you should be able to examine the possible faults you list simply by taking the pan off with the gearbox in the car

[Katzenfreund]

Dear Christopher,

thanks! As you surely can tell from my writing, English is not my first language - I simply misunderstood the stall test and just now realize the meaning of 'stall'...

It is as previously said and as you expressed it: the revs rise uncontrollably.

Please accept my apology.

I will now go to my garage and take care of the problem. The weather is terrible - so working on the Jaguar seems to be a good way to spend this Saturday.