No selection of any gear

[RichardSEL]

Just pulling together an XJ6 series 1 (1972) chassis with only 23k miles on it.
But it's been sitting under a tree for the last 10 years-sh allegedly with only occasional startups

Have now started the engine but the gearbox doesn't select any gear
Just now working on the floor pans and the X-members so thought this a convenient point to access the box

Haven't done an ATF drain and refill and filter change yet -- should I use a flushing fluid too? See that there's Wynne's Auto Transmission Power Steering Stop Leak and Conditioner that's been mentioned in other forums but I think that's a thickener when really I want a thinner of some sort. What flush agent is generally used?

Dunno what box this is as weren't there several makes used in the Series 1's life? And truth be told, never had an XJ6 before
Does the gearbox number give some clue? It's 44098

Would welcome any thoughts...

[mike020150]

The 4.2 litre cars from engine number 7L 8164 were fitted with the Borg Warner model 35 gearbox. Until that point, the BW model 8 was used. With an unknown history and a story of long term standing, getting the box to operate without stripping and cleaning everything will be a gamble. It may be the car was taken off the road for a gearbox fault. Who knows? I'd be tempted to start with a new filter and flushing fluid to see if there is any improvement but be prepared to remove the box for an overhaul. Mike.

[RichardSEL]

Thanks for the fast reply, Mike.

The engine number is 7L 57149 S (from Heritage Certificate)

What flushing fluid do you know? Did a Google search and only that Wynns came up

Borg Warner 35 I know from my days with Rover P5B and P6 -- are they interchangeable with the BW 8?

[Tintin]

I may be wrong, but I was under the impression that some early 4.2 litre cars were fitted with the model 12 box - mine being one of them at engine number 7L 44094.

Robbie

[mike020150]

Maybe I'm being a little pessimistic but I don't rate highly the chances of Wynn's or any other flushing oil clearing such a serious blockage, assuming it is a blockage (rusted ball bearings in the valve block perhaps?) and not a broken pump or similar (try a pressure gauge check). Flushing is worth a try, with all your fingers and toes crossed because removing the box is such a major task. Even removing and working on a valve block with the gearbox in situ can be awkward. The model 35 box was an advance on the model 8 (more responsive etc.) and a lot lighter. For a simple life, it would be far easier to stick with the same type of box rather than attempt to change it. Linkages etc. will be different and getting hold of parts won't be simple. Mike.

[RichardSEL]

I may be wrong, but I was under the impression that some early 4.2 litre cars were fitted with the model 12 box - mine being one of them at engine number 7L 44094. Robbie

Could be as I don't know how to tell the difference between a BW 8 and 12 on this '72MY chassis
On the plate perhaps? I know that the DG250M (Mk IX) has a clearly readable plate...
I'm not down in the workshop ATM

[RichardSEL]

Maybe I'm being a little pessimistic but I don't rate highly the chances of Wynn's or any other flushing oil clearing such a serious blockage, assuming it is a blockage (rusted ball bearings in the valve block perhaps?) and not a broken pump or similar (try a pressure gauge check). Flushing is worth a try, with all your fingers and toes crossed because removing the box is such a major task.

Just a bit hesitant about using that Wynns. Although if it's true and not just fable that ATF can thicken with age then a flush, after these number of years standing, would help

Even removing and working on a valve block with the gearbox in situ can be awkward. The model 35 box was an advance on the model 8 (more responsive etc.) and a lot lighter. For a simple life, it would be far easier to stick with the same type of box rather than attempt to change it. Linkages etc. will be different and getting hold of parts won't be simple. Mike.

I'm getting ahead of myself -- ATF flush & filter first -- engine's sweet But haven't yet let it run up to full operating temperature yet so that'd help. Got to flush the coolant first...

[Tintin]

Could be as I don't know how to tell the difference between a BW 8 and 12 on this '72MY chassis
On the plate perhaps?

The plate is on the LHS of the gearbox, from memory above the level of the floor pan so it's difficult to see - you will need a mirror and torch.

Robbie

[Tintin]

Just a bit hesitant about using that Wynns. Although if it's true and not just fable that ATF can thicken with age then a flush, after these number of years standing, would help

Why not remove the gearbox sump, measure the quantity of fluid you get out and assess its visible condition and any sludge/debris in the pan? You then have a reasonable starting point from which to base a decision.

Robbie

[mike020150]

Apologies for any accidental confusion caused between model 8 and 12 units etc. It's all down to a fallible memory which only gets worse with age! I should have checked definitively before scribbling. The 12 is a development of the 8 used initially in the XJ range and was fitted to 4.2 litre XJ6s from car 7L 8164 (June 1970 onwards). The Model 35 box was only fitted to 2.8 litre cars but its development (the model 65) was fitted subsequently to 4.2 & 3.4 litre series 2 cars manufactured from Dec 1973. Series 3 cars (3.4 & 4.2 litre) used the slightly revised Model 66 box. Mike.

[Tintin]

The W/S manual fault diagnosis table lists the following checks for no engagement in any gear (which I understand is what you have) for the model 12.

Manual valve not connected to shift control
Fluid level
Manual control adjustment
Primary valve sticking
Broken converter drive plate

There are a further 3 checks for which the box must be removed from the car.

Good luck!

Robbie

[Brakebuster]

as tintin says, follow the check list

i would make sure you have fluid in there, and its the correct level, as too little fluid will stop the box selecting gears

i had this when i rebuilt mine ( different box ) , thought i had stuffed it , when it just needed some more fluid after filling the galleries, pump and torque converter

BB

[RichardSEL]

Thanks guys for all the advice -- I've sent it down to the body shop for their checks, so BW 12 box is expected then...

The pax side front floor pan's cut (footwell's are both OK) out but don't know whether this last week they've put the replacement plate back yet. If not, then hopefully it should be easy to see the box's plate from the cabin

[PaulGover]

FWIW, Wynns auto gearbox additive used to be (amongst other things) a light petroleum base whose main purpose was to make the old, heat-hardened seals swell and regain flexibility, thereby curing leaks. It was generally highly rated by DIYers for doing what it says on the can. Also rated for curing power steering leaks, in much the same way. No doubt there were other things in there than just petrol.

The mix may have changed for more modern transmissions, if anyone ever puts additives in them rather than just changing the fluid.

[RichardSEL]

On my '59MY Mk IX had a slight weep from the power steering box on either full lock.
Added a can of Lucas's Power Steering Stop Leak to the resovoir and within 10 miles or so it did exactly what it said on the tin! Was amazed as don't usually believe in snake oil. But that stuff does work!

Going down to the workshop first Sunday next month, so will update then

Found this snippit: "WARMING UP THE TRANSMISSION?: According to a tip passed on from the Heart of America Jaguar Club, if you have a Jaguar with a Borg-Warner automatic transmission (pre-1979 XJ-S), you should let the car idle in neutral for 10-20 seconds before driving. This is because a one-way valve that prevents fluid from draining from the torque converter is unreliable, and the torque converter may have drained. The fluid pump does not function in park, so it must be in neutral to do any good."


BTW, I've got two litres left over of Dexron VI. It's to VW's Tiptronic spec. Can I use that in a BW12 or does it have to be the older ATF? See there's some Dexron II still advertised on eBay