Mechanics

TRANSMISSION SHIFTING PROBLEM V. SPECFIC

2002 BMW X5

Transmission problem
2002 BMW X5 V8 Four Wheel Drive Automatic 65.000 miles

Hi,
I have a problem with my X5 4.4 2002 Auto Transmission.

After driving for a while, such as half hour, the transmission does not shift properly anymore. Usual operation at startup is quite good and not any sign or jerkyness or error message.
The first 10 to 15 minutes the transmission works fine, also it does not feel jerky in any way.

Shifting is also still carried out smooth, however the shifting point is much too high, I need to rev the engine to about 3 to 4K before shifing occurs. Usually it would shift much sooner, around 2K to 2.5K I believe? It definately feels wrong.
It means I drive on the highway only in 2nd or 3rd gear at very high revs. Need to push the pedal hard to force gear shift at v. High revs, up to 5K sometimes.

Shifting down would also occur too soon when comming from higher gears, leading to a jerky braking at traffic lights as the revs are too high on the downshift. But this issue is more irregular whereas shifting up becomes a constant problem after running the car for a while.

I also tried to change gears in manual mode.
When I want to shift into i.E. 3rd gear at revs below 4K it would not engage the gear and the display would show a drop back to 2nd after 3rd was shown on the panel for a brief moment. I felt that 2nd gear was still at work. Same applies to shift gear 1to 2, 3 to 4, etc. I can only do the manual mode shift at high revs (min 3.5 to 4K)

Have had the problem checked and the tranmission cleaned, oil cooler replaced, filter replaced etc. Cost a lot of money but problem re-occurerd immediately on my way home after I picked up the car and drove for over 30 mins.

what could be the problem here? Computer did not produce any error messages either. Could it be a rev sensor, or any other component not directly in the transmission? Do I need to get the transmission disassembled?

Please please help, had already too many problems with this car and spent a ton of money on repairs too : (
Avatar
Moneytree
May 24, 2008.




When did these problems start?

Dr. Hagerty
May 24, 2008.
It started at 65K miles and I drove it to the repair shop immediately. There it was in for a few days and they changed a few things on the transmssion such as coolant, filter, oil cooler. Also the diagnosis didnt show any error message. When I picked it up, after driving for 30 or so minutes without any problems, the same thing happened again with the problems described and now I am waiting what to do and if I should let them dismantle the transmission or could it be a software issue (would be strange though that shifting always works fine in the first 15 minutes?)

Tiny
Moneytree
May 24, 2008.
Could you explain what the justification for replacement of the cooler and the coolant was?

Dr. Hagerty
May 26, 2008.
As the transmission was not functioning properly, esp after being warmed up, the workshop tried to replace items which did not require to open up the transmission. Also they have not found any faults in the diagnosis. I guess this was not necessary?

I did some more driving yesterday and found that shifting occurs too late, for any gear. It should shift much quicker up into third, but now it shifts so late the fan blows quite loud and I hardly hear the engine rumble any longer.
Could it still be a software or sensor issue or would it be transmission parts?

Tiny
Moneytree
May 26, 2008.
As to the unnecessary replacement of the cooler, yes it was not needed. As to the issues with the late shifting and no faults being set, what method are you using to extract faults?

Dr. Hagerty
May 27, 2008.
The method if GT1 diagnosis and it did not show any fault. So this would rule out any sensor issue?

However I can confirm that, at high temp when the car is warm, the tranmission misses to shift at the right RPM, i.E. Shifting still, but too late. Downshifting can also be too early but this problem is less pronounced.

Importantly, before this problem occured, I had a leak in my cooling system and the engine was running on low water for some time until smoke came out and the car was towed. Could have been overheated slightly, but BMW confirmed no damage was done to engine.

However the transmission could have been damaged by this? Where could the problem be, as the diagnosis does not show faults at all.

Tiny
Moneytree
May 27, 2008.
The problem with the transmission first occurerd after I had a leak cooling system fixed, but it was fixed at this auth. BMW shop so I assumed it was all fine, hoses, water pump, thermostat, etc were all replaced and everything checked.

The first time the transmission misssed to shift gears occured I was stuck in traffic jam and driving over 1 hr before the transmission started to act funny and not shift up properly, generally just felt " wrong". Driving on highway didnt make it better, at too low gears. So I drove it to this shop immediately.

After the shop didnt find any error message and did the service of the GB the problems came up again after driving for some time. Last 2 days, no problems occured, but I noticed the fan constantly operating at any time, whilst engine was normal temp, which was not the case before.
Drove high speed/high temp several times, but with fan ON: No problem occured with the trans. Probably due to the cooling effect of the stuck fan?

Could it be possible that the fan clutch has failed and the fan was *off* after the cooling leak was fixed, which led to temporary overheat of the transmission and temporary failure?
I noticed the fan stuck on *On* is a recent issue, so perhaps it was stuck in *off* previously after the leak fix, leading to transmission overheat and unsmooth gear changes? And now is stuck in *ON* making the problem go away?

I am now getting the fan issue fixed and will see then if the problem re-occurs at " normal" driving before doing anything to the transmission. I now hope that the trans only acted because the cooling system didnt work properly due to lack of fan operation in hot climate and dense traffic. Would this be realistic to believe? Would this explain lack of error messages in the GT1 diagnosis?

If yes, great news, but I hope this 1 or 2 times overheat did not do any permanent damage to trans. This morning drove to work, all was perfectly fine (with FAN on).

Tiny
Moneytree
May 28, 2008.
1.) Alternator broke - break down on highway
2.) Got problem fixed at BMW shop
3.) Another break down the next day, hose was leaking, noticed steam comming out from the enginebay everywhere, drove only 1 mile or so, engine was running without or very little coolant, temp reader was normal. Tow to BM shop again
4.)They mentioned with the new alternator they did a flush of the cooling system and this flush has removed debris which may have accumulated in the cooling and lead to expose leaks in the hoses. Hose broke and along with it water pump and thermostat was replaced due to " leaks".

Picked up the car from BM and driving was ok.

4.) A few days later, issue with gear shifting came up in heavy taffic. Temp reading inside car was normal (could the fan be off here and lead to trans failure due to overheat? I did not pay attention to fan operation at all)
I assumed gearbox problem.

5.) Brought the car to BM shop, explained issue with GB, they serviced/cleaned the gearbox, changed fluids and magnets, pan etc. Fluid seemed ok. After testdrive, they called me to say can pick up car.

6.) On way back, trans problem occured again after 30 mins driving on highway. Gear shift up very late, down shifting also not smooth and too early.

7.) Last few days, noticed the fan was stuck in *on* at any speed. Even after extensive driving at high speeds/acceleration, problem with gearbox did not re-occur.

Now my question: does the shifting behaviour resemble that of overheated gearbox? I read somewhere that if the gearbox is too hot, it will shift much sooner rather than later.

And would this fan issue not show up as an error message in the GT1?

Tiny
Moneytree
May 28, 2008.
The fan issue will probably not show up on the short test. The transmission issue is now gone, yes?
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Dr. Hagerty
Jun 8, 2008.
I have a 01 X5 4.4 that did the same thing. I had a coolant level error, then a coolant temp check. While pulling off the road the radiator blew. I had the radiator replaced.

Yesterday while driving the vehicle became stuck in 3rd gear. I was driving in heavy traffic and did not over rev the car. I shut it off and restarted it and everything was worked fine after that. I have not had it happen since, but haven't driven in heavy traffic.

Did you ever find out what caused this in your vehicle?

Tiny
BMWLEO
Jul 17, 2009.

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