Oh my that is way too hot. I'm assuming you're driving 'normally' and not towing an 18 wheeler up a mountain when you get those temperatures. I'm not sure specifically about the ZF but that temperature is usually considered overheating. My gearbox (a GM5) goes into an emergency mode to reduce damage when that temperature is reached.
You almost certainly either have some clutch slipping or else the cooling circuit is blocked.
What diagnostic codes are you getting? The ECU can detect many different types of faults, some directly and some indirectly. It can for instance tell that a clutch is slipping by measuring the input and output shaft speeds and calculating whether it makes sense. Such detected faults will not necessarily show up on the dashboard LCD but will show up on the diagnostic tool.
If there are no such faults indicated then it is most probably a cooling circuit fault as it has no direct way of detecting that. The most common thing to cause the problem would be blockage in the water side of the oil/water heat exchanger. I don't think it would be too difficult to take it off the engine and check/clean and if necessary replace it.
You will spill some oil and water but be extremely careful not to contaminate the oil either with the coolant water or anything else.
Mine seems to be around 100C whenever the RR is up to running temp - although no idea if mine is anywhere near 'normal'..
This is after coolant change, heat exchanger + mounting and and thermostat change, plus gearbox oil and filter change, plus gearbox temperature sensor change!!!
Overheating is caused either by a faulty cooling system or by too much heat generation. The former is usually simply a matter of unblocking the heat exchanger whereas the latter is a more difficult problem to solve and will usually require removing and dismantling the gearbox.
When the cooling system is OK and the box still runs too hot it means that more heat is being generated than the cooling system is designed to handle. In an automatic gearbox that almost always means a problem with one or more of the mutiplate-clutches slipping, which is a problem that should be detected and reported by the ECU. The slipping can be caused either by worn out clutches or by insufficient hydraulic pressure.
If you have a diagnostic tool like IIDtool you can start a log recording some of the parameters of the gearbox then go for a drive and analyse the log afterwards. The important parameters to record are the engine RPM, turbine RPM, output shaft RPM, system pressure, lock up clutch hydraulic pressure, gearbox oil temperature, engine coolant temperature and throttle opening.
The drive should preferably include many different conditions and speeds and preferably wide throttle opening so as to stress the gearbox. After the drive these values can be plotted and you can determine whether any of the clutches are slipping. You may also be able to see which of the gears is raising the temperature quickly.
I'm not getting any codes on the dash or in the diagnostics scanner. I'm using the icarsoft I930. My thermostat isn't working I have a fault code for it
Is that the engine coolant thermostat. Not sure if the trans cooler stat will show a code. If you are running on the original trans cooler and rad has been changed then you are very likely due. Our trans gave an overheat message shortly after purchase when on an emergency run to NYC for my wifes mother. No issue for a year and then trans failed with the trans failsafe message as a precursor to the failure. Were you using a laser thermometer to measure those temps. When I removed the trans cooler the oil side was fine but the rad side was totally plugged (I bandsawed it in pieces). The trans stat could also fail i suppose which might restrict flow to the cooler. I changed the manifold the cooler plugs in to as a precaution as another member on here suggested. Ours was ok but its not an expensive part. Got parts from Island 4x4 and cooler is a behr original at a best price from what I had researched. My advice is not to delay the replacement if it is old or you are uncertain. I did not change the trans stat which could be a failure point. I had also done the ghur stat change to one with a slightly lower running temp. A plug and play from an older bmw engine (diesel) I believe. Check his posts for the part Number. There were 17 left in Germany when I got mine thru a local bmw dealer. Cost me 170 Cdn. Have had a couple of messages re incompatible temperatures but they clear with a regular scanner and no adverse effects on anything I can think of.
Yes it's the engine cooler thermostat. I'm not sure if anything ever was replace from o.e.. I change the coolant manifold gaskets and valley pan. The radiator drained fine before the change. The overheating started after s shop replaced my alternator and did cooler seal install on the lines to transmission because there is a oil fluid leak from somewhere around the the housing.
.... The overheating started after s shop replaced my alternator and did cooler seal install on the lines to transmission because there is a oil fluid leak from somewhere around the the housing.
That says it all. Looks to me like the mechanic reassembled incorrectly possibly blocking the flow of oil or water with an incorrectly placed or incorrectly cut gasket.
Go for a short drive to raise the temperature, then with the engine still running check the temperature of the inlet and outlet pipes from the heat exchanger.
If the temperature of both pipes is more or less the same as the gearbox temperature and almost the same as each other then the water side of the exchanger is blocked.
If one pipe is much hotter than the other or both are similar but much cooler than the gearbox temperature then you have a partial or full blockage on the oil side.
In any case once you solve the heating problem, or perhaps even before, have the gearbox oil level checked by a competent mechanic. There is a very specific procedure that needs to be followed - its not just a matter of opening a filler plug and looking.
If you're able to monitor temp, try watching it from cold, and see if it rises gradually, or suddenly spikes.
There are issues with the internal trans fluid temp sensor on this unit.
If it really is getting that hot during normal driving, and you're not constantly power braking it, I'd be looking at the TC, and the cooling system, the trans t-stat, cooler, and radiator itself for flow in it's lower cores.
Oh come now lister, it doesn't take a mechanic to check fluid levels. Let's give folks on the site a bit more credit than swamp swilling morons. :roll:
stics, make sure you have RAVE. checking tranny fluid is not as complicated as he makes it sound.
Yes I will check the lines for blockage. However I drained the fluid and changed filter and gasket pumped all fluid back in. It drove at around 102 celcius. for about 45min one way trip. Then i noticed the fluid on the garage floor the next day. I then checked the level at 30c to 50c and got no stream so i pumped more fluid in. i never got the stream because I ran out of fluid. I'm thinking it keeps getting low because of the leak. Today i got a closer look at where the leak my be. it seems to be coming from the transmission breather that is where I found oil sitting in the grooves on top and the hose and rubber were wet. the breather is loose and easy to turn and moves like its not seated properly. Is it a press fit? The clip is free spinning also. Thanks for the suggestions and tips
Transmission oil temperature back up to 135c. When my thermostat failed the transmission oil temp remained at around 103c. Once I replaced the thermostat the transmission oil temp goes up to 135c. I just replaced the radiator. Could the problem still be a blockage somewhere. I noticed white paste substance in lower coolant hose. Also I cleaned out white paste from the transmission breather pipe. I think it's cause the previous owner used green antifreeze. I haven't yet to pull the trans cooler and inspect for more white paste. I also have trans fluid leak. Any suggestions well appreciated?
135c seems like it.might be your sensor bad. 135c is pretty hot for fluid.
I have an 06 so it uses the 6spd zf 6hp26. Normal temps for it, even while driving pretty aggressive or towing a large trailer are under 90c usually under 85c.
When I was driving with a defective TC and it wasn't locking, my tranny ran EXTREMELY hot under normal driving and would usually run 95c and upwards of 105c when driving hard.
If my sensor was bad would I have got the overheat warning message. I'm not getting any overheat messages. I just been monitoring the temperature with scanner and live data. I'm thinking just change out the cooler anyway since i been replacing other coolant system parts. if I'm correct the temperature sensor is in the same areas as cooler
You need something to calibrate the resistance reading against. Do you have one of those cheap infra-red laser thermometer thingies that you can point at the sump pan to give you an idea of the true fluid temperature?
Replaced trans cooler with a new one and I'm still experiencing high temperature on gearbox oil. I'm also getting a torque converter cirtuit dtc code. I'm wondering if its time for a rebuild.
Curious if the water side of the cooler was plugged. Ours had clearish minerals that totally blocked the cooler. It could mean that your rad is plugged at that level and will not let water flow thru your new cooler. It could also be that the trans cooler stat is not operating properly. You may have to reboot the trans ecu by disconnecting the three harness clips and reconnecting and then shut off and restart the engine. But do test the resistance of the trans temp sensor as phil has suggested. Phil had been kind enough to reply to a query of miner and provided the chart?temp comparison. 1500 ohms at 30 C plus/minus iirc.(approx) A laser thermometer may help you pinpoint the various in/out temps of oil and water.
Diff, The rad was replaced last year, the old one leaked from the sides. Before I installed the new cooler, I removed the transmission lines blew air through them both. I also took off the cooler t-stat and water passage housing cleaned it out and reinstalled. is there any way to check the cooler t-stat because its mechanic and not an electric part. I tried to move the spring but it didn't budge. i also notice the parts drying turning into white flakes after rinsing. Also , as Phil suggested i finally picked up a laser thermometer. My I930 temp reading shows about 15-20c higher than when I point the thermometer at the sump pan. I will check the resistance as suggested. I had to get the necessary tools together and understand the graph going forward. Does the key need to be on when checking resistances?
Hi. I never checked our t stat although I should replace it anyway. I think you may have to put it on the stove and boil water and see if it opens. Phil has shown connector 1835 and it is very easy to check the resistance when you disconnect from the trans ecu and follow the pin numbers for the 2 pins that relate to the resistance of the trans temp sensor. So when engine is just started the trans temp should be ambient so you should be at 1000 ohms or so. This is actually the same concept as electric floor warming cable which use a temp/resistance sensor to turn a thermostat on and off. Ours responded perfectly and iirc you do not need the key on as you are measuring a variable resistor. The only thing that got us working on the overheat message was to disconnect the 3 trans ecu plugs-while engine running-it bucked on disconnect and reconnect-shut down and restart and everything perfect ( till the tranny failed a year later from A drum failure)(not related I think). So if you have the laser thermometer you can check in and out temps of oil and water thru the cooler (and compare to trans oil pan temp) which should show something-our readings indicated no issues but still we had overheat messages. Our trans ecu got so hot i think you could have cooked eggs on it but i have yet to find what makes them fail.
Results of the resistance test.. silver cooler line =88c , green line =63c trans oil pan laser on green sticker =76.5c, resistance =1596 ohms and the i930 temperature reading =108c. What do you guys think? This is after an 1hour and half of medium traffic driving and couple of stops. Sat for ten min after shutting off!
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