Trans Temp with edge tuner.

[cameron10]

Hello, I have a 2003 Chevy Silverado 2500HD with a 6.6 Duramax LB7 and Allison trans. Just got the truck about a month or 2 ago and it has 243k miles. The other week I was on some back roads in my hot tune (previous owner installed a edge tuner with 6 tunes) I noticed my trans started acting funny and when i looked at the trans temp it was about 30 or 40 degrees higher than what it usually runs at. (Usually runs around 120). As I was driving in the hot tune it kicked me out of gear and i came to a stop and put into park then back into drive. When i went to accelerate, it did not want to get going, it acted hesitant. Not only that, but it never left first gear. Let the truck cool down for about 10 mins and the trans was perfectly fine. I usually drive this truck in the 3rd tune which is a drive tune, no issues with the trans temp or the trans acting up on me in that 3rd tune. Today, i decided to throw it into the hot tune to see what would happen just driving around. I did not get hard on it simply drove it around the town. Temp went up to 160, about 40 degrees higher than when im driving in my drive tune. Bumped it back down into my drive tune and hit the highway, almost immediately temp started going down and about 10-15 mins on the highway it was back down to 120. So, my question is, should i get a more heavy duty trans cooler? Why did the trans not shift out of first when it got to around 160 temp while in my hot tune? I have many questions and not a lot of knowledge about the Allison's and the Duramax. I will provide as much information to you smart people who help me.
Thanks in advance.
Cameron.

 

[TheBac]

What you are experiencing is limp mode. These trucks arent indestructable, although they are close.
The hotter tunes on a stock trans will eventually wear internal parts out and cause the limp especially on higher mileage trucks like yours. IMO, a larger cooler wont necessarily help fix the issue once it starts. Keep it out of the hotter tunes bc it will only get worse from here on out. Time to consider a trans rebuild.

 

[2004LB7]

Are those temperature numbers in F or C? Because if they are in Fahrenheit then that's not even warmed up at only 120. 160 is almost there. Now if they are Celsius then 120 is ok but 160 is too hot and can cause the transmission to act funny.

You most likely are slipping clutches and it's heating up the fluid. And causing the limp mode Tom mentioned. I'd also start saving for a transmission rebuild if you want to play in your hotter tunes

 

[08lmm72mm]

Sounds like the torque converter is hurt. Did it throw any codes? If it didn't I suspect the TC is hurt and that's what is causing it not wanting to move and the higher heat being generated. Only solution here is change trans oil and filters, drive on stock level power until you can get a built transmission.

The allison is a great transmission but it isn't designed to handle more than 100ft/lbs over stock output.

 

[cameron10]

What you are experiencing is limp mode. These trucks arent indestructable, although they are close.
The hotter tunes on a stock trans will eventually wear internal parts out and cause the limp especially on higher mileage trucks like yours. IMO, a larger cooler wont necessarily help fix the issue once it starts. Keep it out of the hotter tunes bc it will only get worse from here on out. Time to consider a trans rebuild.

That was what i was worried about lol. I'm sure the previous owner beat that trans all to crap before he handed it down to me. Oh well, time to learn how to re-build a trans

 

[cameron10]

Are those temperature numbers in F or C? Because if they are in Fahrenheit then that's not even warmed up at only 120. 160 is almost there. Now if they are Celsius then 120 is ok but 160 is too hot and can cause the transmission to act funny.

You most likely are slipping clutches and it's heating up the fluid. And causing the limp mode Tom mentioned. I'd also start saving for a transmission rebuild if you want to play in your hotter tunes

Those numbers are in F. I was thinking it was weird that 160 it starts acting up when 160 is almost close to being warmed up. I was planning on re-building it just not this soon lol.

 

[cameron10]

Sounds like the torque converter is hurt. Did it throw any codes? If it didn't I suspect the TC is hurt and that's what is causing it not wanting to move and the higher heat being generated. Only solution here is change trans oil and filters, drive on stock level power until you can get a built transmission.

The allison is a great transmission but it isn't designed to handle more than 100ft/lbs over stock output.

No codes were thrown when it all happened. Okay, i will baby it until i get that trans re-built.

 

[08lmm72mm]

No codes were thrown when it all happened. Okay, i will baby it until i get that trans re-built.

You could get it up to hiway speed in 5th gear at as low rpm you can, turn the power up to max and give it as much throttle you can see if the rpms come up (to indicate slipping converter clutch) without making it downshift and see if the rpms climb. Either way those 5 speeds aren't meant for much extra power, especially at your mileage. How does the fluid look?

 

[cameron10]

You could get it up to hiway speed in 5th gear at as low rpm you can, turn the power up to max and give it as much throttle you can see if the rpms come up (to indicate slipping converter clutch) without making it downshift and see if the rpms climb. Either way those 5 speeds aren't meant for much extra power, especially at your mileage. How does the fluid look?

I tried to do it on the highway, was being followed by a sheriff both ways lol. But, the fluid looks really good.

 

[cameron10]

Sounds like the torque converter is hurt. Did it throw any codes? If it didn't I suspect the TC is hurt and that's what is causing it not wanting to move and the higher heat being generated. Only solution here is change trans oil and filters, drive on stock level power until you can get a built transmission.

The allison is a great transmission but it isn't designed to handle more than 100ft/lbs over stock output.

i lied, it threw a P0700 transmission code.

 

[TheBac]

P700 is just telling you that there are trans codes. Find a code reader that can read the TCM.

 

[cameron10]

P700 is just telling you that there are trans codes. Find a code reader that can read the TCM.

Okay, I should have that code reader hopefully within this week. I’ve noticed my instrument cluster is no longer displaying what gear I’m in. It’ll only show the line under R when i put in reverse. But, for N, D, and P, there is no line under said letters. I through it into drive and sometimes it’ll make a hard clunking noise then it’ll show that line under D. When I go from drive to park, it acts like I’m still in drive so it won’t unlock the doors and when I open the doors it’ll ding at me that the door is open. Could this be some sort of sensor? It is my trans just completely screwed?

 

[BrandonLLY]

When I’m towing my LLY trans gets to 220-230 with no problems. 160 degrees Fahrenheit is nothing.


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[2004LB7]

Okay, I should have that code reader hopefully within this week. I’ve noticed my instrument cluster is no longer displaying what gear I’m in. It’ll only show the line under R when i put in reverse. But, for N, D, and P, there is no line under said letters. I through it into drive and sometimes it’ll make a hard clunking noise then it’ll show that line under D. When I go from drive to park, it acts like I’m still in drive so it won’t unlock the doors and when I open the doors it’ll ding at me that the door is open. Could this be some sort of sensor? It is my trans just completely screwed?

You can always try and replace the nsbu switch

 

[cameron10]

When I’m towing my LLY trans gets to 220-230 with no problems. 160 degrees Fahrenheit is nothing.


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Good to know. Idk why it threw itself into limp mode when it got to 160. I’ll throw it back into my hot tune and see what happens with trans temp.

 

[cameron10]

You can always try and replace the nsbu switch

Okay, I’ll look into said tonight after work. Thank you.

 

[cameron10]

P700 is just telling you that there are trans codes. Find a code reader that can read the TCM.

50 transmission codes popped up when i went to read them.

 

[wydopenLb7]

When I’m towing my LLY trans gets to 220-230 with no problems. 160 degrees Fahrenheit is nothing.


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Sorry for the off topic post but what kind of ect's are you seeing with your trans temp that high? Im towing around 13k lbs with my LB7 up some big mountains and my trans temps are at most 10deg less than my ect, usually 20-30deg less....reading it on a cts3 insight..

 

[BrandonLLY]

Sorry for the off topic post but what kind of ect's are you seeing with your trans temp that high? Im towing around 13k lbs with my LB7 up some big mountains and my trans temps are at most 10deg less than my ect, usually 20-30deg less....reading it on a cts3 insight..

Around the same 220F. This is a reading off my edge and my gauge cluster. Never had a problem over heating. Although I am speaking of towing in 90-100 degree ambient temperature. I think that’s all in normal range. I also am towing up very steep and long grades at freeways speeds.


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