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Hey guys so I have noticed my trans temp climbing just driving down the road on flat roads not climbing any hills or anything. My trans use to sit roughly 150-160 now it’s been getting to 200-205 out of nowhere. I have 07.5 lmm I’ve already replaced the outer filter roughly 3000 miles ago the oil is not low at all. Any help would be great trying to figure out why it’s getting so hot
 

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I'm not up on the 07.5's, but in the slightly older trucks, the things to check:
  • Some sort of clutch debris could collect where the transmission lines go into the radiator; check with an infrared thermometer; if suspicious, remove line into radiator and check/clean/blow-out out any debris.
  • Check for crud clogging up the cooling stack, but the engine would probably be running hotter than normal, too, although you can't trust the dash gauge (check at OBDII with a scanner/monitor).
  • ATF level; a little too high and the temps go up; should be about 1/4 up the hot hash marks at 170*F.
 

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Hey guys so I have noticed my trans temp climbing just driving down the road on flat roads not climbing any hills or anything. My trans use to sit roughly 150-160 now it’s been getting to 200-205 out of nowhere. I have 07.5 lmm I’ve already replaced the outer filter roughly 3000 miles ago the oil is not low at all. Any help would be great trying to figure out why it’s getting so hot
i would flush the trans and replace both filters. if that doesn’t work, you might have a plugged up trans cooler or a bad torque converter
 

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Could be wrong, but I was always under the impression that you weren't supposed to flush the allison when doing a fluid change. A double drain is preferable
 

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Could be wrong, but I was always under the impression that you weren't supposed to flush the allison when doing a fluid change. A double drain is preferable
'Flushing' in this post refers to removing all the old trans fluid and replacing it with new, and not using a pressure based flushing machine that forces fluid thru the trans. Also this means using the HOOT METHOD to remove the old fluid. Yes, you can do a double drain and that works, but the HOOT METHOD is quite simple and saves you money.
 

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Not sure about the newer Allisons, but my LLY got slightly overfilled and began to overheat (220-230) while towing up hills. I removed enough fluid to bring the level just below the hot full mark when trans was hot, temps came back to the usual 160-170F. If slightly overfilled, the fluid can foam and cause overheating so make sure it's below the hot mark when fully warmed up.
 

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Ah, I wasn't able to glean that much detail from the use of the word "flush" lol
 

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Hey guys so I have noticed my trans temp climbing just driving down the road on flat roads not climbing any hills or anything. My trans use to sit roughly 150-160 now it’s been getting to 200-205 out of nowhere. I have 07.5 lmm I’ve already replaced the outer filter roughly 3000 miles ago the oil is not low at all. Any help would be great trying to figure out why it’s getting so hot
Clean the cooling stack it will go right back to normal I went through all kinds of crap trying to figure it out. It's usually a full on rug infront of the radiator grass, dirt bugs, mine was about a 1/2inch thick.
 

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Hey guys so I have noticed my trans temp climbing just driving down the road on flat roads not climbing any hills or anything. My trans use to sit roughly 150-160 now it’s been getting to 200-205 out of nowhere. I have 07.5 lmm I’ve already replaced the outer filter roughly 3000 miles ago the oil is not low at all. Any help would be great trying to figure out why it’s getting so hot

With what your dealing with temps running higher than normal just driving around not towing no grades usually means it’s time to clean the stack.
There are plenty of discussions on doing this.

Hoot method i wouldn’t suggest this, one good way of making a big mess, possibly causing trans issues especially if your doing this by yourself.
More people have cussed doing the hoot method over the ones that’s been satisfied doing it this way.
Double drain is safer, getting the front up at least 6” higher than the rear letting it set at least overnight allows for the fluid to drain back down into the pan you might even get by with one drain.
If you pull the pan change the internal filter and spin-on then doing it this way one drain should be enough.

Get one of these to drain in, then you’ll have a closer idea on how much fluid to put back in.
Allison Transynd TES-295 is my choice or Allison approved TES-295 trans fluid.
 

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