Hi all,

I had a weird issue develop coming back home yesterday. For the first half of the journey, the gearbox was perfectly normal, but then when on some country roads it appeared that the torque converter was staying locked up permanently.
I first noticed, when coming to a junction, a very clunky change down to first. Then, when accelerating away, it would not change gear until 4000rpm no matter what I did - lifting off the throttle, coasting - engine revs still stayed locked to road speed. I put it into sport and tried changing up manually, the light briefly flashed from 2 to 3 or 3 to 4, but would then immediately flash back again. Slowing down, the changes were very jerky as though someone was changing down and dumping the clutch back in on a manual box without rev matching.
I pulled over, put it in park and switched off. I started up again, and pulled away gently, and the gearbox was fine again - driving very gently, it was changing all the way up into 5 properly at about 2500rpm each time.
However, when I then hoofed it out of a busy junction and it held the revs to about 3500, the problem reoccurred and it locked solid again, refusing to change up so I had to roar through a village holding 4000rpm in 2nd at 30.
Again, I pulled over, switched off for a minute, and again it was fine - until again I accelerated a bit harder to hold a gear and it again locked up.

Can anyone please shed some light on why it would be doing this? My only thought would be that the gearbox was getting too hot - given the 30 degree temperature, and the very stop-start journey I'd had through towns most of the way, so the convertor was locking up to try and help the oil cool down? However, there were no warnings at all on the dash to indicate an overheating 'box.

The gearbox is the 5-speed ZF in a 2005 BMW V8.

Thanks,
Matt NW060

"Red Shed" - 1982 Series 3 88" County Station Wagon
"Spirit of Great Britain" - Rolls Royce Meteor V12 engine
ZG875 - Westland Sea King (cockpit section)
"Carly Rae Jeepsen" - 2006 Jeep Commander 5.7 Hemi
"Pride Of The Road" - 1/4-scale Marshall traction engine - sold
"Georgina" - 2000 Discovery 2 TD5 ES - sold
"Windsor" - 2005 Range Rover Vogue 4.4 - dead

Could it be engaging the cooling strategy because the gearbox is overheating , usually a sign that the cooler is blocked . Might be time for a new radiator as the bottom elements are the gearbox cooler . 2008 MY Supercharged
Rimini Red / Jet
four zone climate
remote park heater
and no ugly kid windows.
magnus satis quod turpis satis

It was happening to me over a period of a month and things came to a head coming back along the M56 from Manchester airport last week. I got a message up saying transmission fault followed by HDC fault. Then sat nav & radiator went of and all indicators stopped working. The dashboard warning lights tarted doing wierd things as well. Very disconcerting. Phoned friendly indie and he said it was alternator or battery. Turned off all non essentials like sat nave, radio, air con and transmission started working normally. Next day took it into them and they diagnosed faulty alternator - by this stage the battery light was permanently on. New alternator solved problem. Fuel economy now up to + 30 mpg again!

Does sound like the gearbox going into cooling strategy, as said blocked gearbox oil cooler or pipes, faulty gearbox thermostat or blocked main rad...

Get it checked out soon and get the gearbox oil changed asap when you have sorted the problem...

Low battery on your model tends to throw the Transmission failsafe mode... Pete
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Thanks for the replies chaps, it seems I was on the money then.

The only thing I don't get is why it would start such obviously major modifications to its behavior without an accompanying "warning: gearbox temperature" or similar message coming up on the dashboard?

I will check the paperwork tonight, but I'm sure the seller mentioned having had the gearbox oil done in the last 10k miles or so. Would getting hot have damaged the oil in any way?
Does the oil cooler simply run oil through a special matrix in the bottom of the rad, or does it have a heat exchanger to cool it using engine's coolant system?
I dont think there are any problems with the main rad itself - the coolant was changed 4 weeks ago and even in hot stop-start traffic, it stayed resolutely in the middle of the temperature gauge. NW060

"Red Shed" - 1982 Series 3 88" County Station Wagon
"Spirit of Great Britain" - Rolls Royce Meteor V12 engine
ZG875 - Westland Sea King (cockpit section)
"Carly Rae Jeepsen" - 2006 Jeep Commander 5.7 Hemi
"Pride Of The Road" - 1/4-scale Marshall traction engine - sold
"Georgina" - 2000 Discovery 2 TD5 ES - sold
"Windsor" - 2005 Range Rover Vogue 4.4 - dead

The cooling strategy is the car actively trying to avoid a "Bong" 2008 MY Supercharged
Rimini Red / Jet
four zone climate
remote park heater
and no ugly kid windows.
magnus satis quod turpis satis

The gearbox has its own dedicated cooler/rad, they are renowned for blocking up causing your issue... Members above are suggesting you check your gbox fluid as it has now probably been burnt!
So, get cooler changed (ASAP) and have gbox fluid changed at the same time to protect yourself from any further damage accruing sir

And just because the car runs at normal temp, does not mean the main rad isn't blocked, the top of the rad cools the engine, the bottom cools the gearbox, sludge builds up and settles in the bottom of the main rad... you can't flush it out, and flushing agents won't touch it... I know, I tried everything...

I replaced main rad, oil cooler rad, oil cooler thermostat, manifold and both oil cooler pipes....

Now runs nice and cool, at the age yours is at they want changing if you plan on keeping it for a while....

FYI the temp gauge gets to "normal" at around 85deg, it doesn't move off normal until about 115deg, most cars do this now, they make then so it shows what the driver expects to see rather than what is actually happening..... Pete
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Thanks for clearing that up guys, I'll look into an oil change with a new gearbox cooler and lines asap.

I notice the cooler is a strange block-like thing, is this in addition to running it through the bottom of the radiator? NW060

"Red Shed" - 1982 Series 3 88" County Station Wagon
"Spirit of Great Britain" - Rolls Royce Meteor V12 engine
ZG875 - Westland Sea King (cockpit section)
"Carly Rae Jeepsen" - 2006 Jeep Commander 5.7 Hemi
"Pride Of The Road" - 1/4-scale Marshall traction engine - sold
"Georgina" - 2000 Discovery 2 TD5 ES - sold
"Windsor" - 2005 Range Rover Vogue 4.4 - dead

The transmission cooler is an oil-to-water type that receives its coolant flow from the bottom eight rows of the main radiator (controlled by a thermostat). When the bottom of the radiator (or the water side of the oil cooler) gets blocked the cooler has nothing to cool the transmission fluid with so the fluid overheats. The transmission fluid doesn’t go near the main radiator.

Click image to enlarge

Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated

Not to steer away from topic, but does this normally happen ( lock up holding lower gear, say should be in 5 and wont go into forth manually ) when towing??

How easy is it to change the cooler....im thinking of changing mine after my FF held 4th quite a bit on a long run back with a horse box on tow.
Just to say I have changed the oil a month ago now and have not had a rumble ( cattle grid affect) since the change so caught that in time I.

Radiator was changed about 16 month ago there about too under warranty. If it dont work.......burn it!

If the IId tool cant fix it.......burn the FF.

If the FF cant be fixed......buy a Land Cruiser!

If the LC cant be fixed..............................................BUY a horse !!