Trans temp is running really high on my D8N 9TC02614. I've narrowed down why but I haven't been able to find the fix. The torque converter inlet pressure is 0 outlet pressure is subsequently also 0, so no flow to the cooler. I disassembled cleaned and reassembled the pressure and selector valve body and valves still no pressure. Everything looks to be assembled correctly. Pump pressure is around 400, my smallest gauge goes to 3500 and has 50 psi tick marks so hard to get a good read to 10 psi. Any thoughts on what else to check would be appreciated.
I would suggest that you get hold of a 100psi gauge and check converter outlet pressure again. You can’t measure it with a 3500psi gauge because it will be wildly inaccurate at close to zero pressure.
Sounds good I'll see what i can find.
If you had o torque inlet pressure it wouldn’t move.
That's why I was so confused. Hooked up smaller gauge on start with cold oil the outlet pressure rose to 61 psi then maintained about 60.5. When I did the stall test the pressure dropped to 45 psi. Returning to low idle the pressure dropped to 10 psi. It would go back up to 45 with throttle. I don't have two hoses to hook up the lower pressure gauge to the inlet and outlet at the same time. Inlet pressure initially 75 psi, wide open throttle no load 145 psi, and low idle back to 75 psi. The pump maintains just over 400 psi at all throttle positions except low idle when it drops to about 375. I have owned this machine for five years and the transmission has always ran hot. I just replaced the torque converter and the cooler, because I assumed that's why it was getting hot.
When you say this are you going off the gauge indication on the dash or have you confirmed actual temperatures such as cooler in/out, etc, with an infra-red heat gun.?
Just looking at the gauge in the dash, I'm guessing it close to correct. When the trans temp starts getting hot the engine also goes up. The engine typically running around 190 ish once the converter hits 230+ engine will get around 210.
I'll try an infrared gun to check.
I think it would be a good idea. If the gauges are not accurate then you could be worrying unnecessarily. Check the temperature of the top coolant hose into the radiator and the bottom one out of it. That will give you a good indication of how well the radiator is cooling. Question. When was the last time the radiator was removed and given a good clean both inside and out.?
Two years ago disassembled to replace seals and cleaned cores, then flushed with the cat cleaner until I had clean water coming out.
Well that ticks one box. However when you get the heat gun and check coolant in/out temperatures at the radiator you are looking for a temperature drop of about 18DegF for a cooling system in good condition. Next questions……. Condition of fan belts, pulleys, and tensioner.? Any chance the fan is installed backwards.?
That all looks good, I've fixed all the rubber around the outside of the shroud. The fan blows dirt off the blade.
It will always blow in that direction whichever way round it is installed. Some don't realize that. If it's installed backwards it will be far less efficient and will move much less air than if it's installed the right way round. A photo of the fan will tell the tale. This is really a box-ticking exercise just to make sure that all the simple things are right before starting to look at the expensive stuff.
Just to give an update so that anyone that reads this in the future. I replaced the torque converter, the pump, and the cooler. That didn't do it. Then pulled the trans and had a friend of mine rebuild it. He said he only found a couple things wrong a couple seals that were bad and a plate in it that is suppose to be smoothe that had some grooves wore in it. It is not getting nearly as hot anymore but it was still running pretty hot so I checked the oil temps at the cooler and the filter with an infrared thermometer and found the gauge wad not reading correctly. Changed the guage and it went down to a decent temperature range. I can work the snot out of it all day now with no issues.
That was an expensive Parts Cannon you fired off only to find a defective temp gauge. I think the I-R temp gun idea was suggested as a first step by quite a few people, myself included.
Sure was, trans did need rebuilt anyway the first gear clutch where about done, probably didnt need the torque converter. I really think alot of the problem was the cooler. I really started having issues with it after someone drive it with the parking brake on (I found the valve put together wrong so you could drive it with the brake on) it completly shredded the brake clutches in the right hand drive. All that clutch material ran through the system plugged the filter and my bypass alarm wasnt working, so it likely plugged up the cooler as well. The machine has around 32000 hrs on it so we kind of have to keep throwing new stuff at it regularly to keep it going. Cat oil samples tell me the motor is next.
Thanks for the honesty and replying back. Good bit of information, you have a better machine now and maybe for a while will have peace. Simon C
Yes,agree with Simon C,the machine has many new parts now that were possibly needing looking into anyway.If they are keeping it,then not necessarily money down the drain
Hey guys, Reading about the transmission over heating and it looks like everything was checked out properly, but did anyone mention the transmission thermostat?? I have an older D5B-LGP and trans kept running hot (her temp. gauge was good). I replaced the trans. oil and filter, cleaned her cooler, check for cooler flow, etc. It turned out that all she needed was a new trans. thermostat. The local CAT dealer said that thermostats rarely go bad and told me that I probably had internal transmission issues. I was literally dumping cold soap water onto her transmission housing while running to get me through finishing a job. I then ordered a new thermostat; a cheap fix compared to pulling out her damn transmission, about $135.00 for a new CAT thermostat. My thermostat housing was located up by the trans. oil cooler in front of the engine radiator. That fixed my problem. She went right back to normal temperature. B.C. in Maryland
Good suggestion. See the attachment. If the temperature regulator has not already been replaced you should seriously contemplate doing it, and my advice would be to use a genuine OEM part as opposed to a will-fit.
I have an update as well now that the transmission was shedding it heat the engine was overheating. Just changed the thermostat. Put the old one in boiling water and it doesn't open. Good chance it's been the problem the whole time.