Transmission temp too high?..

[diyanich]

Keep in mind that there's a thermostat for the transmission fluid.
It's located above the heat exchanged( 8 shaped black plastic with 3 hoses connected to it)
Normal temp is 82C mine is running hotter sometimes up to 106C
I get fault codes.
I already bought the thermostat as well as x-rings for heat exchanger(they are leaking once in a while) and now waiting for x-rings that go between thermostat and radiator,should be in next week.
If interested I can post the parts numbers.
I doubt that sensor is wrong,keep in mind that there's a ration for the spot: distance.... like 1 : 8,so you aren't measuring the actual spot if you are far from it

Originally Posted by turquise1

Yes my transmission is still acting up. Same issues, after driving for a while, I will come to a stop, I step on the gas, car would not move, with higher rpms, it would jump and there is your TRANS FAIL SAFE..(Transmission is rebuilt twice, module replaced and still happening)

There is also that delay between P, R, N and D issue)

So, I do more research, and find out many people with these symptoms had valve body wiring harness issues. The temp sensor would not work properly and tranny would overheat and go crazy.

So, I decide to check the temperature in many different ways. After a half an hour warm up, the INPA soft shows gearbox temp as 100C. I read 180f from outside using my infrared thermometer (not sure how reliable). Also, my basic error reader reads Transmission fluid temp as 91F.

Now, thats confusing, I would think that 100C is too high and in that case the temp sensor is reporting wrong.

A recent visit to a transmission mech, and the guy there said my tranny fluid is burnt (changed only 2 months ago).

What do you guys think..

Ozzie..

[civdiv99]

For a variety of non-performance reasons, BMW upped the engine operating temp from an acceptable mid-190s(F) to 225(F). this caused it's own batch of issues brought about because in the (most) X5 era, BMW's engine management systems were still running narrow band sensors and going open loop under load, so they had to band-aid with more knock sensors, etc.

Since the trans cooler is really just a little BS heat exchanger, your trans fluid will run well over 200F. Many, many in the trans field will opine that such temps are too high, and such temps shorten the life of the orings, and various plastic and rubber parts internally. Others will point out that the mfr knows best. Skeptics like me will say the mfr may know, but they ain't necessarily gonna tell all.

It's important to realize that this transmission was used in a plethora of makes and models NOT running BMW's temps nor the all-spendy secret squirrel sauce. (is my jaundiced viewpoint of BMW's band aids coming out yet?)

So yeah, your trans is running at what most would call high temps. But then so is everyone else's. Well, except mine. However, while the temps certainly aren't ideal for an auto tranny, this is probably not the root cause of your issues. I dunno (obviously, just sitting' over here) what the problem is, but if everything was up to snuff, then it'd work. In other words, the temps aren't the cause, but they aren't helping any.

Unfortunately, while not a big deal to throw on a stand-alone cooler, that's not the answer here. IF your fluid exhibits signs of heat distress, it's not because of operating temps, but may be a result of localized heating from slipping plates (your slip bang crash issues are slipping).

Originally Posted by turquise1

Yes my transmission is still acting up. Same issues, after driving for a while, I will come to a stop, I step on the gas, car would not move, with higher rpms, it would jump and there is your TRANS FAIL SAFE..(Transmission is rebuilt twice, module replaced and still happening)

There is also that delay between P, R, N and D issue)

So, I do more research, and find out many people with these symptoms had valve body wiring harness issues. The temp sensor would not work properly and tranny would overheat and go crazy.

So, I decide to check the temperature in many different ways. After a half an hour warm up, the INPA soft shows gearbox temp as 100C. I read 180f from outside using my infrared thermometer (not sure how reliable). Also, my basic error reader reads Transmission fluid temp as 91F.

Now, thats confusing, I would think that 100C is too high and in that case the temp sensor is reporting wrong.

A recent visit to a transmission mech, and the guy there said my tranny fluid is burnt (changed only 2 months ago).

What do you guys think..

Ozzie..

[SlickGT1]

I wasn't saying your mechanic doesn't know his shit. I am saying anything could have happened, and you need to exclude oil. Now let's leave out the fluid brand for a second. Check your level. You issue really sounds like a pressure problem. Pressure loss will cause extra heat as parts aren't fully lubed, or engaged, or slipping. It's possible the valve body is screwed. But again it only happens when warmed up. And the fact that you are fine in manual mode leads me to think torque converter. Was that replaced?

Manual mode locks up the TC and uses completely different logic. The fact that it locks up the TC brings us back to pressure, which brings us back to fluid level, which brings us back to fluid speck. Now it is also possible your TC is toast, or the rebuilt unit is messed up. Chances are if your shop replaced it, the got a rebuilt somewhere. I've read of botched up rebuilt TC. Your mech probably can't rebuild it himself as that requires special equipment and skill set.

[JCL]

Sounds like the wrong fluid as a starting point. If it is burnt, you have other problems, which changing the fluid doesn't fix. Confirm that first. It isn't the viscosity that is important, it is the fluid friction properties which directly impact clutch engagement characteristics. Clutches slip, that makes heat, and that burns the fluid. Clutches also slip because of valve body problems, which it looks like you have experienced.

I don't think there is anything wrong with your fluid temperatures. They run hot. They are designed to.

Temperature sensors failing in the valve body wiring harness aren't related to temperature control. They are there to adapt clutch engagement pressures and times to the actual fluid temperature. So if the sensor malfunctions, the computer doesn't know if the oil is hot or cold and the electronically controlled shifts won't be correct.

Low oil level isn't likely the cause IMO. The transmission has had interventions more than once. Not likely the oil level would be wrong every time.

Manual mode doesn't lock up the torque converter. It just changes the shift logic (ie it doesn't shift automatically unless it needs to protect the transmission).

Recall that trans fail safe is just a computer message that means "this doesn't compute". The various sensor inputs don't add up to what should be happening, so the transmission throws up its hands and says it doesn't know what is going on, so it is going into a limp mode as a precaution. Just about anything could cause it, it isn't a diagnostic signal of any sort. Could be mechanical, hydraulic, or electronic.

[SlickGT1]

You right JCL it doesn't lock up the TC. I need to stop drinking and posting at night. Lol.

[TwinTurboGTR]

Tisk Tisk Slick! lol.

[SlickGT1]

Went to see Harvey yesterday, came home a bit plastered. So what's a fella to do when sitting on the throne and the head is spinning. Check the forums. Lol.

[turquise1]

Hey guys,

I am certainly not defending my mechanic (he works with this tranny guy, who I am actually frustrated with) but I really do not know what to do anymore, and yes I still love my X5 and do not wanna replace it.

Here are all the details once again.

TC was replaced with a new one. I replaced the cooler and its thermostat myself but the two hoses going into tranny are old (could they be clogged?). I have replaced the TCM with a used one and same stuff kept happening. ABS module was rebuilt. I replaced the speed sensors. Transmission guy replaced the valve body with a rebuilt one (he said) and I still had the issues (I also have the delay from P,R,N to D, thats why I suspected valve body).

My wife just told me the car went into failsafe mode without even warming up after shifting from R to D, but after turning the engine off/on, everything is fine again.

Here are the errors I have on TCM (INPA) :

- Stall speed
- Gear check 2,3

No errors on ABS module, but there are some others on IKE etc. (I can post them if you think they are relevant)

I am going back to my mech on monday to check the tranny fluid and ask some questions..

Thanks for all the help, once again..

Ozzie..

[TwinTurboGTR]

Yeah, there is no way after two teardowns or one teardown and one check up that it should act that way. Completely unacceptable. Question him on the fluid and on resetting adaptations. Even after doing a tranny fluid and filter replacement, people complained the tranny was acting weird, but after resetting the values, all was good in the world again.

SO IMHO, if the tranny guy replaces the fluid and resets the values and the X is working fine, I'd find another tranny guy after the warranty has expired.

Hope you can get it straightened out Monday.

[turquise1]

Great help guys, I really appreciate it!

I also did not know what exactly the temp sensor inside the transmission would do. I am assuming since the viscosity of oil changes with the heat, the sensor helps to make shifting adjustments according to that.

I am getting the oil checked tomorrow (correct? burnt?) and will ask for a new wiring harness installed.

Will let you guys know whats happening..

Ozzie..