XSeries-forum

[quote="jonnyivy"]
Good reading your experience there,...no way would I try that !!
My problem is that there are many recommendations / warnings from so many differant specialists.
Some are saying it needs full rebuild, some saying it cant be put back together with out new mechatronics,..then I read the forums and some are saying just change the oil.
Of all the ZF specialists I have spoken to none have said changing the oil will do any good and it will be just throwing money down drain... but cant help thinking when its cold and thick it behaves much better in the gears.
I really dont think my transmission is so bad,..I'd be happy to drive it all day without breaking down but some warn this will eventually go bust.
I spoke briefly with the last owner who said it was a BMW mechanic who told him it only needed a new torque converter ? !!....
Isnt it strange that once you kinda know what might be wrong with your box you tend to concentrate more on its behavious and noise of engine while you drive. I'm always sitting with ears tuned into the sounds as we drive along lol...
Maybe still just dis-miss any of my own thoughts and just find the cash to get this rebuilt sooner rather than later....
[/quote]

The reason the gearbox acts better when cold will be down to the viscosity of the oil, basically it's thicker. If you think about it the box uses oil pressure to transmit the torque n power of the engine into usable rotation force. If you have worn clutch packs which is what you have, you'll have bigger gaps between the packs, thicker oil will take up the excess tolerances. When the oil warms up and thins then we get issues

It's the same with much older or worn engines, you'll need thicker oil to cope due to excessive tolerances

I did think of trying to suck out some oil from the filler with a tube and a syringe to see what it was like and get some idea of whats going on in there.
If it was only needing a change of oil I would never live it down if I had laid out best part of 2 grand to build a gearbox that didn't really need it (at this time).
I have a wife and two kids to keep happy over Christmas and its a pretty lean time in winter for my job as a landscape gardener !!...so taking that money for this repair will need to be well justified, although we both love driving the X5.
I've been studying the workings of a torque converter and automatic gearbox functionings on youtube  etc..... and finding it very interesting and I can see where the oil has such a crucial part to play. I do think my T/C needs replaced as I dont seem to get that complete "lock-out" in top gear unless I ease back on the throttle.
I'm gonna phone Birch tomorrow and let him know that I will be postponing the job till new year (nothings been booked in yet , but he offered next Monday start ).
I think I will sleep on it tonight ...

Jonny

Reading on Discovery forums I came across a rather interesting article.

Apparently one of the major failure modes with the gearbox, taking into account the D3 used the ZF 6 sp, was glycol contamination due to leaks from the oil cooler in the radiator.

There is a place that can test for this but can't remember where it is...

Might be worthy of taking a sample and getting it tested?
Even if it rules it out?


BTW.  If you are getting any major work done on a gearbox then it is commmon sense to in the min get the torque converter examined/overhauled/replaced.
Chances are that if you have a pressure problem then the lock up clutch will be worn and possibly on its way to fail!!!