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transmission oil temperature

28K views 41 replies 12 participants last post by  Gadzooks2 
#1 ·
My transmission oil temp is reaching almost 140 celcius. What is the normal temp supposed to be? 2005 zf5hp 24
 
#28 ·
I check the resistance at startup and got 1056 ohms at 32c. The sensor seems fine. Now as I was driving today I got a pO745 code with is the pressure control solenoid A fault. Now the temperature raising faster to transmission overheat a lot sooner than before. Is the this solenoid the same as the pressure regulator part sold for zf 5hp24 transmissions. I wonder if I replace that would the problem go away or I'm I facing more serious issues?
 
#30 ·
Thanks Phil Yes I did get a torque converter circuit fault Po740. I cleared it to see if it was gonna come back and it does sometimes. Can I check the solenoid to see if it's working properly. Does the pressure regulator solenoid have any thing to do with my issues too. I was wondering if I should order that part for the valve body also.
 
#31 ·
On the temp measurements one would think that the pan temp would be very close to the hot side of the trans cooler and the cool side of the trans cooler seems like quite a lower temp so that cooler seems to be really working well-seems way better than any numbers i got when testing ours. You may have to try a few different spots but that parts seems good as does the resistance findings.
 
#32 ·
I checked all the solenoids and they read 6-7ohmn and the other 3 where 29ohmns. The wire loom solenoid connectors where very brittle and started to break into pieces. I notices to discolored pins on the connector end. How would I be able to tell if my tcm is bad?
 
#33 ·
My code scanner is reading 15 degrees higher temps than the pin resistance reading and the laser thermometer. I'm getting overheat message at 150 degrees celsius on my display. I disconnected the three TCM plugs while the truck was running and it didn't shut off. However when i turn the key off and try to restart with the plugs disconnected it doesnt crank unless I plug the connectors back in the TCM. I do receive dtc when the plugs are disconnected on my diagnostics scanner. My question Does the truck supposed to stop running after the tcm is unplugged while running? What does this pinpoint what can be bad?
 
#34 ·
Hi all, I'm getting this exact thing. Reading of 975ohm at the ECU plug however my value in IIDTool is 40degC which is 15 deg above the ambient temp seen at the Transfer Case and Rad @ 24/25degC. So I gather that the incorrect reading is either the IIDTool or the ECU? Attached readings on IIDTool

Any help would be appreciated,prefer to not drop pan and install new parts without actually knowing what the issue is :)
 

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#35 ·
#37 ·
I didn't replace the factory cooler because it is extremely hard to get to and the hose connections are a real bitch to get off. If they get damaged coming off the whole hose needs replacement and that is expensive as is the factory cooler. Even a new factory cooler will only buy you time until it clogs up again unless you do constant complete cooling system flushes. The aftermarket air to oil cooler will never clog up as it doesn't have any water passages to clog. It also can keep the fluid cooler since it is not in contact with 200 degree coolant.
 
#38 ·
I recently did a full flush + am of the preventative mindset normally. I don't mind throwing new coolant in it every 12-24 months and doing a full block flush. Peace of mind as the truck gets sent to remote locations (sand, heat, Australia) often :)

I was considering plumbing in a cooler after the factory one, I'm mindful of creating too much change in the cooling system, prefer to augment what is already there.
 
#39 ·
My transmission oil temp is reaching almost 140 celsius. What is the normal temp supposed to be? 2005 zf5hp 24
How were you able to check the temperature? I have an 06' and I want to change the fluid but it has to be at 50 degrees celsius and I do not have a thermometer to check the oil temp. Is there a way in the gauge cluster or the nav screen? Thanks!
 
#40 ·
The correct temperature for checking the transmission fluid level is 40°C. If the temperature gets up to 50°C you should theoretically abandon the checking procedure and let it cool down. Depending upon the ambient temperature where you are, the fluid temperature will probably already be at 10-20°C before you start, so the fluid will reach 40°C with the car stationary and the engine just ticking over for 5 minutes.

The fluid normally operates at 100-110°C, so is a lot closer to ‘cold’ than to ‘hot’ when you check it. The most important thing is to have the engine ticking over while the fluid level is being checked. Whether the fluid temperature is within a few degrees of being correct is much less critical. The volumetric coefficient of expansion of transmission fluid is around 0.0007/°C, so a 10°C error is equivalent to only 67cc of fluid based on a capacity of 9.5 litres.



Phil
 
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