loss of gears on a jatco

[triumphtr7]

Okay first off I'm a mechanic so dont worry about baffling me with science.
Heres the question,before ripping the auto box out of Dads 75, has anyone come across the jatco box losing gears? There was no warning of this,just went to put it in reverse and nothing. Now this I have heard of so tells him to bring it over. He puts it in drive and pulls away....1st,2nd,3rd.....no 4th or 5th or lock up and of course no reverse!
So gets the manual out looks at the pressure flow diagrams,solenoid opening/closing sequence for gear selection and can see no way that it can loose 4 gear ratios and still have 3 working.
Has anyone come across this before?
Cheers

Dave

[crofts]

Well I'm not a mechanic so won't even try ! !
The only 2 specific problems that I am aware of are a) The cracked piston/cylinder that seems to be more prevalent in the earlier boxes. Jatco have a modified part hence the later boxes are not as prone. (I think from about 2003 on)
b) Then recently a member had solenoids replaced but cannot remember the symptom. What I can recall is that box removal is not necessary to correct.
Should pick this up if you do a search (& perhaps other leads will come up)

[Phil]

Is the display reading normal? IE P,N,R,4,3,2 etc, or does it say EP?

[Dragrad]

My story....... There may be some pointers therein.....

http://www.the75andztclub.co.uk/foru...t=26236&page=9

That was my experience

[triumphtr7]

Thanks for the replies guys
Phil there is no error code
Crofts- cracked solenoids or shorts on the windings normally result in jerky changes/slipping in and out of gears etc
Dragrad Thanks for the info but you dont say what your mech replaced and it sounds like you suffered complete loss of drive?
On the old mans(v6 by the way) its as smooth and seamless as its always been from 1st to 3rd.

Any more thoughts gents
ps oil is at level and clean

Think I'm going to have to rip this out to be honest,going on T4 next week but I have a suspicion it will show "no fault found"

Any more thoughts gratefully received.

Dave

[Dragrad]

Originally Posted by triumphtr7

Dragrad Thanks for the info but you dont say what your mech replaced and it sounds like you suffered complete loss of drive?

Sorry, thought it was included in that thread. The mechanic tried a common quick fix without the need to take off the box. But as it transpired he had to take it off to replace the piston, and some other bits. Apparently a common fault in his view was that the main piston gets porous, inferior metal

He replaced with the newer uprated kit, box is now fine (fingers crossed - which makes typing a little difficult ) Cost (including car hire) was about £1700.00

Yes it was a total loss of drive, but only whilst the fluid was warm. If cold I had minimal drive for a couple of minutes, but not enough for a second attempt to get the car onto the RAC's tow truck.

[crofts]

That sounds a lot Andrew but, of course don't know how much car hire was.
Member andyBB had his cacked piston/cylinder replaced with modified Jatco part for around £600 by JR Transmissions, Farnborough (Tel:- 01252548337)
Knowledgeable guy 'cause I spoke to him about it and what fluid he uses. He had the data sheet from Jatco re the mod.
He also brought to my attention the use of the later spec. Texamatic 7045E fluid.

[34by151]

Try replacing the fluid first. If that does not help put some miles on it and replace a second time. Each fluid change only gets about 2/3rd of the fluid.

If the fluid is really low you will get not drive at all

If the level is low check for leaks. It is not uncommon for the lines to the cooler to rupture.

To test the solenoids and sensors with a multimeter read my post here for the values.

http://forums.mg-rover.org/showthread.php?t=278761
Post no 7

Jim

[triumphtr7]

Thanks Jim,fluid already done,and what came out was clean and no leaks anywhere to be seen. To be honest the way the jatco works low oil level would result in loss of all gears but probably only after the gearbox had got unbareably noisy and sluggish to change. Whats happened to this box is extremely strange and not the usual jatco problems.

Dave

[crofts]

Originally Posted by triumphtr7

Thanks Jim,fluid already done,and what came out was clean and no leaks anywhere to be seen. To be honest the way the jatco works low oil level would result in loss of all gears but probably only after the gearbox had got unbareably noisy and sluggish to change. Whats happened to this box is extremely strange and not the usual jatco problems.

Dave

Please come back and let us know what you find Dave. Did you do a search ? (Click search at top right and type in Jatco or autogearbox. Might reveal something for you !)