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Old 29th August 2019, 22:19   #1
Bernard Fishtrousers
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Default Autobox questions...

I have a V6 auto and a couple of questions: First, in normal use, it's appears desperately reluctant to kick down a cog or two unless I select sports mode, but when I do so, it appears never to find its way back into top gear. Does 'sport' actually prevent it from selecting fifth or does it change back up at about 90mph or something? Secondly, I'm normally a very lazy driver and am happy to potter about with the smoothness of 'snow' mode. Will prolonged use of this boil the ATX & wreck the box or is it OK? Finally how often should I change the transmission fluid, it's covered about 65K & I suspect has never been changed.

Thanks in anticipation,
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Old 29th August 2019, 22:33   #2
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I have a V6 auto and a couple of questions: First, in normal use, it's appears desperately reluctant to kick down a cog or two unless I select sports mode, but when I do so, it appears never to find its way back into top gear. Does 'sport' actually prevent it from selecting fifth or does it change back up at about 90mph or something? Secondly, I'm normally a very lazy driver and am happy to potter about with the smoothness of 'snow' mode. Will prolonged use of this boil the ATX & wreck the box or is it OK? Finally how often should I change the transmission fluid, it's covered about 65K & I suspect has never been changed.

Thanks in anticipation,
Sport mode will still go into top gear but you will be doing seriously illegal speeds when it does.

Potter about in snow mode if you want to, it does no harm, just disengages 1st gear.

I would be changing the fluid now if I were you just to ensure all is well.
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Old 30th August 2019, 06:54   #3
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Originally Posted by Bernard Fishtrousers View Post
I have a V6 auto and a couple of questions: First, in normal use, it's appears desperately reluctant to kick down a cog or two unless I select sports mode, but when I do so, it appears never to find its way back into top gear. Does 'sport' actually prevent it from selecting fifth or does it change back up at about 90mph or something? Secondly, I'm normally a very lazy driver and am happy to potter about with the smoothness of 'snow' mode. Will prolonged use of this boil the ATX & wreck the box or is it OK? Finally how often should I change the transmission fluid, it's covered about 65K & I suspect has never been changed.

Thanks in anticipation,
check throttle cable adjustment.
when in sport, it will not select lock up on the converter (to stop slip), you might think that is a gear!
Snow mode starts in 2nd, so here you might also have "lost" a gear if you count! It does no harm to use snow mode, just slow mode, really.
I would change the oil, if I was you.
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Last edited by kaiser; 30th August 2019 at 07:31.. Reason: Snow mode in stead of sport
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Old 30th August 2019, 09:32   #4
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... in normal use, it's appears desperately reluctant to kick down .... unless I select sports mode ...
Hi Dave,

The crankcase breather holes in the cam covers are blocked. Behind the gauze filter on the suction side there's a pinhole restriction which becomes blocked with carbon (particularly if the official 15,000 miles oil change interval has been followed ). Clear it using a piece of wire or suitable tool taking care that the particles don't end up in the engine. Start with the LH bank cover and observe the tightening sequence when refitting it (see Haynes). The RH bank cover is underneath the manifold chamber so requires a lot of dismantling. The end result will be worth it though. Your engine will feel as if it has gained another litre of capacity!

Simon
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Old 30th August 2019, 11:24   #5
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Hi Dave,



The crankcase breather holes in the cam covers are blocked. Behind the gauze filter on the suction side there's a pinhole restriction which becomes blocked with carbon (particularly if the official 15,000 miles oil change interval has been followed ). Clear it using a piece of wire or suitable tool taking care that the particles don't end up in the engine. Start with the LH bank cover and observe the tightening sequence when refitting it (see Haynes). The RH bank cover is underneath the manifold chamber so requires a lot of dismantling. The end result will be worth it though. Your engine will feel as if it has gained another litre of capacity!



Simon
My diesel is reluctant to kick down whilst locked up. Always has done, and I am guessing that the op assumes lock up to be 5th as.i did when I first got the car (I may be wrong here of course), so it gives the appearance of a sleepy kick down.

Cleaning.the breathes is always going to.be a good.idea, but not sure how it would affect the car in this situation.

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Old 30th August 2019, 11:34   #6
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Surely the box is the same as in my old XJ8?

I'm still at the stage of counting the gear changes & can't quite work out at what speed the torque convertor locks up. It was about 50mpg in the Jaaaaag, but there still seems to be some slip when travelling faster than that in the 75?

On a positive note however, it tells me that it's doing 33 mpg, Coventry's finest sadly only managed 21 !
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Old 30th August 2019, 11:55   #7
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Surely the box is the same as in my old XJ8?

I'm still at the stage of counting the gear changes & can't quite work out at what speed the torque convertor locks up. It was about 50mpg in the Jaaaaag, but there still seems to be some slip when travelling faster than that in the 75?

On a positive note however, it tells me that it's doing 33 mpg, Coventry's finest sadly only managed 21 !
Surely not! This is a Jatco (Nissan) box for front wheel drive cars. It is also fitted to the 2 liter X -type. Your Jag most likely had a ZF from Germany.
(Who one the war??)
You will see when the torque converter locks up, doing a steady speed on a straight road. There will be a drop of approximately 300 revs, when it locks!. That is the converter locking up eliminating slip . If you press the accelerator, the rev counter will rise in unison with the speedo. If not in lock up, there will be a slight increase in revs before there is any noticeable acceleration. Go and try, and it will be clear.
Now go and change the fluid, and let us know the outcome.
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Old 30th August 2019, 15:56   #8
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Lock up is very subtle and unless you listen for it and have a very sensitive right foot, you will miss it. As said, you will only feel it lock on a long, straight road when auto top gear has engaged. Too hard a push on the go pedal and it will release.
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Old 26th September 2019, 15:54   #9
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Now go and change the fluid, and let us know the outcome.
Apologies for my tardy response.

Holes behind the gauzes were squeaky clean, the accelerator cable had some slack and the ATF was stinky, stinky and grey.
Throttle cable tightened, ATF changed for new, and thing are improving. I still have to kick down with some vigour, but it now changes down and the engine finally pulls some revs. I've seen 6,500 rpm for the first time this afternoon. Still not as quick as the Jaguar or the Porsche, but it does seem to make a rather pleasant noise.
In other exciting news, I've finally got the radio to emit sound, so all in all, I am a happy bunny.
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Old 26th September 2019, 16:46   #10
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I still have to kick down with some vigour ... I've seen 6,500 rpm for the first time this afternoon.
That's a bit excessive for a Rover. We normally proceed in a gentlemanly fashion without the need for flamboyance.

Have you checked that both your VIS actuators are operational? It's common for the valves to become stuck in mid position which plays havoc with the engine's intake breathing.

Simon
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