hi all ive got a 1999 p38 witha gearbox fault! it turns out ive lost top gear had it scanned and theres no faults in the computer , oil is still clean and a nice red! any one got any ideas??

many thanks james

Hello,

Do you mean your torque convertor is not locking up so you get direct drive?

james84 said:

hi all ive got a 1999 p38 witha gearbox fault! it turns out ive lost top gear had it scanned and theres no faults in the computer , oil is still clean and a nice red! any one got any ideas??

many thanks james

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If you are sure it is taking the gear, linkage etc, then it could have broke a brake band in the gearbox.

I'm only guesing here coz I'm a bit out of touch with auto's however, and it might be pish, but the servo in the gearbox operates a band which grips a clutch giving you drive, if it's broke then the servo will still work and no fault code registered but no drive.

This entails you taking the sump off and looking for the band thats broke, you might have to take the valve block off though to get to it. The one I did I changed the band but you have to ensure you get it adjusted correctly so I counted all the threads on the adjusting bolt and set it the same.

That's only one theory so check it out before you do anything. It might be something more simple.

James,

I used to get this with my P38 if I turned the ignition on and started the vehicle quickly.

If I turned the ignition to position I, waited for a second until I heared a click and then started the engine, it was fine.

Strange ...but true.

Hi James
I have 1998 p38 BMW auto with similar problem , recently had Becm unit overhauled and immobilizer removed , the gearbox problem only happened couple of times previous to this but now its happening intermittently on a regular basis. The problem is as follows
sticks in 3rd then eventually goes into top gear and sometimes changes from 4th to 3rd when it should be in 4th.
the filter, oil and oil cooler have been changed but hasn't made any difference.
WOULD APPRECIATE ANY ADVICE thanks Paul.

the trouble im having is it wont engage 4th full stop goes to change up from 3rd and intead of revs dropping and engaging 4th it revs up slightly then continues to rev in 3rd!!! completely lost 4th! to start it was interminant then one day no 4th! but it first happened when i was accelatring hard in sport mode then tried changing up and nalt! so if any one has a good place for me to start loooking would help like i said had it scanned and no electirc faults!

James

PS- if anyone see's my 4th gear any where can they please let me know as i want it back! lol

post 3 seems a good place to start! snaped brake band, logical diagnosis!

can brake bands be replaced with out removing and stripping the gearbox or can they be done with it in?

james84 said:

can brake bands be replaced with out removing and stripping the gearbox or can they be done with it in?

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If you think that this is the problem then I did one in place, but don't know if your gearbox is the same.

This is how I did my last one.

Take the sump off, after draining the oil and saving it in a clean container, if you want you can filter it before refitting it with a paint sprayers paint filter.

Check the linkage inside the sump and that it is moving the plunger through all the gears first.

Look for the broken band.

The valve chest probably will be in the way and it looks like a massive task to get it off, but it's not. All the pipes are held in with tension, take a photo of them then pull them all off, unbolt the valve chest and carefully remove it.

Make sure everything you use is clean, a nice sheet of carboard to lay everything on.

Unbolt the band and remove the adjusting bolt, pry it open and slip it off, its "C" shaped and the adjusting bolt clamps the open part of the "C".

Best to get a manual on one to guide you, but it's not rocket science.

When you refit it all and start it, dont rev it up let it idle for a few minutes or you risk burning a clutch.

Hope this helps you, mine was a rover borg warner but can't remember the model, and it might be different from yours but look at the manual and see if you can identify the parts I described.

Don't you know an auto specialist to bounce this theory off, they are not usually very helpful on the phone but if you go in person then I have found them ok. There is a series of pressure tests you do to diagnose faults but it's a garage job.

Hate to think it's a relay or sumut, but would have thought a fault code would have been logged.

Ask on here for the down load for that vehicles manual, sure somebody has it.