What is a safe transmission temperature?
#11
06-05-2009, 09:56 PM
#12
06-05-2009, 09:56 PM
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The transmission over temp is at 275*F.
From the service manual.
Trans Over-Temp Indicator Lamp-On Message - Each time the cluster receives an electronic trans over-temp indicator lamp-ON message from the PCM indicating that the transmission fluid temperature is 135 °C (275 °F) or higher, the indicator will be illuminated and a single chime tone is sounded. The indicator remains illuminated until the cluster receives a lamp-OFF message from the PCM, or until the ignition switch is turned to the OFF position, whichever occurs first. The chime tone feature will only repeat during the same ignition cycle if the indicator is cycled OFF and then ON again by the appropriate lamp-ON and lamp-OFF messages from the PCM.
From the service manual.
Trans Over-Temp Indicator Lamp-On Message - Each time the cluster receives an electronic trans over-temp indicator lamp-ON message from the PCM indicating that the transmission fluid temperature is 135 °C (275 °F) or higher, the indicator will be illuminated and a single chime tone is sounded. The indicator remains illuminated until the cluster receives a lamp-OFF message from the PCM, or until the ignition switch is turned to the OFF position, whichever occurs first. The chime tone feature will only repeat during the same ignition cycle if the indicator is cycled OFF and then ON again by the appropriate lamp-ON and lamp-OFF messages from the PCM.
#14
06-05-2009, 10:00 PM
The reason I posted this topic is because I had read in a few places on the diesel truck forums that the most you wanted your trans temp to get to when towing was 200 degrees. Apparently if you keep the temp below 200 degrees your transmission will last a long long long time, but if you start getting sustained temps over 200 degrees, you will start seeing early transmission failures. I was wondering if anyone else had heard the same thing.
The idiot lights don't really apply here. All they will do is tell you when your transmission is already so overheated that transmission failure is imminent. They won't tell you the transmission is running too hot for a nice long transmission life, but that you may have a transmission go out at 60,000 miles if you keep running it at that temp.
Being as our trucks have the great digital transmission temp gauge it would be real easy to monitor trans temp while towing, and when it gets above a certain number, just back off the throttle and let things cool down again. But what temp? What have you folks heard?
I drove the same canyon today that I had towed the trailer up before this post. But today I drove it without a trailer, and just a dirt bike in the back of my truck. Max transmission temp today was only 164 degrees. So this isn't an issue if you are not towing, or are towing on level ground. The time I saw a transmission temp of 208 was at the end of a 4000 ft climb in elevation, while towing the trailer.
MOPWR2U
The idiot lights don't really apply here. All they will do is tell you when your transmission is already so overheated that transmission failure is imminent. They won't tell you the transmission is running too hot for a nice long transmission life, but that you may have a transmission go out at 60,000 miles if you keep running it at that temp.
Being as our trucks have the great digital transmission temp gauge it would be real easy to monitor trans temp while towing, and when it gets above a certain number, just back off the throttle and let things cool down again. But what temp? What have you folks heard?
I drove the same canyon today that I had towed the trailer up before this post. But today I drove it without a trailer, and just a dirt bike in the back of my truck. Max transmission temp today was only 164 degrees. So this isn't an issue if you are not towing, or are towing on level ground. The time I saw a transmission temp of 208 was at the end of a 4000 ft climb in elevation, while towing the trailer.
MOPWR2U
Last edited by MOPWR2U; 06-05-2009 at 10:08 PM.
#15
06-05-2009, 10:02 PM
The reason I posted this topic is because I had read in a few places on the diesel truck forums that the most you wanted your trans temp to get to when towing was 200 degrees. Apparently if you keep the temp below 200 degrees your transmission will last a long long long time, but if you start getting sustained temps over 200 degrees, you will start seeing early transmission failures. I was wondering if anyone else had heard the same thing.
The idiot lights don't really apply here. All they will do is tell you when your transmission is already so overheated that transmission failure is imminent. They won't tell you the transmission is running too hot for a nice long transmission life, but that you may have a transmission go out at 60,000 miles if you keep running it at that temp.
Being as our trucks have the great digital transmission temp gauge it would be real easy to monitor trans temp while towing, and when it gets above a certain number, just back off the throttle and let things cool down again. But what temp? What have you folks heard?
I drove the same canyon today that I had towed the trailer up before this post. But today I drove it without a trailer, and just a dirt bike in the back of my truck. Max transmission temp today was 164 degrees.
MOPWR2U
The idiot lights don't really apply here. All they will do is tell you when your transmission is already so overheated that transmission failure is imminent. They won't tell you the transmission is running too hot for a nice long transmission life, but that you may have a transmission go out at 60,000 miles if you keep running it at that temp.
Being as our trucks have the great digital transmission temp gauge it would be real easy to monitor trans temp while towing, and when it gets above a certain number, just back off the throttle and let things cool down again. But what temp? What have you folks heard?
I drove the same canyon today that I had towed the trailer up before this post. But today I drove it without a trailer, and just a dirt bike in the back of my truck. Max transmission temp today was 164 degrees.
MOPWR2U
Plus, we have a lifetime warranty. I am already talking to the wife about having this truck in 10 years when I retire and want to buy a camper. I really want to pay it off and never have a car payment again.
#16
06-05-2009, 10:06 PM
Part of an article I found.
An automatic transmission creates a lot of internal heat through friction: the friction of the fluid churning inside the torque converter, friction created when the clutch plates engage, and the normal friction created by gears and bearings carrying their loads. It doesn't take long for the automatic transmission fluid (ATF) to heat up once the vehicle is in motion. Normal driving will raise fluid temperatures to 175 degrees F., which is the usual temperature range at which most fluids are designed to operate. If fluid temperatures can be held to 175 degrees F., ATF will last almost indefinitely -- say up to 100,000 miles. But if the fluid temperature goes much higher, the life of the fluid begins to plummet. The problem is even normal driving can push fluid temperatures well beyond safe limits. And once that happens, the trouble begins.
At elevated operating temperatures, ATF oxidizes, turns brown and takes on a smell like burnt toast. As heat destroys the fluid's lubricating qualities and friction characteristics, varnish begins to form on internal parts (such as the valve body) which interferes with the operation of the transmission. If the temperature gets above 250 degrees F., rubber seals begin to harden, which leads to leaks and pressure losses. At higher temperatures the transmission begins to slip, which only aggravates overheating even more. Eventually the clutches burn out and the transmission calls it quits.
An automatic transmission creates a lot of internal heat through friction: the friction of the fluid churning inside the torque converter, friction created when the clutch plates engage, and the normal friction created by gears and bearings carrying their loads. It doesn't take long for the automatic transmission fluid (ATF) to heat up once the vehicle is in motion. Normal driving will raise fluid temperatures to 175 degrees F., which is the usual temperature range at which most fluids are designed to operate. If fluid temperatures can be held to 175 degrees F., ATF will last almost indefinitely -- say up to 100,000 miles. But if the fluid temperature goes much higher, the life of the fluid begins to plummet. The problem is even normal driving can push fluid temperatures well beyond safe limits. And once that happens, the trouble begins.
At elevated operating temperatures, ATF oxidizes, turns brown and takes on a smell like burnt toast. As heat destroys the fluid's lubricating qualities and friction characteristics, varnish begins to form on internal parts (such as the valve body) which interferes with the operation of the transmission. If the temperature gets above 250 degrees F., rubber seals begin to harden, which leads to leaks and pressure losses. At higher temperatures the transmission begins to slip, which only aggravates overheating even more. Eventually the clutches burn out and the transmission calls it quits.
#17
06-06-2009, 08:08 AM
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#18
06-06-2009, 10:24 PM
The highest temperature I'd let the transmission stay and maintain is 175*F, like it was said earlier. and 180-195*F for BRIEF amounts of time, 5 minutes or less. Sustained temperatures of that high will burn you fluid right up.
I have no idea why manufacturers are bent on putting the tranny over temp light so high. By the time that light comes on, you might as well get a hold of your favorite transmission shop, because your tranny has already been permanently damaged.
I have no idea why manufacturers are bent on putting the tranny over temp light so high. By the time that light comes on, you might as well get a hold of your favorite transmission shop, because your tranny has already been permanently damaged.
#19
06-09-2009, 05:33 PM
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Well, I towed my boat this weekend (4,750 lbs w/ trailer), with tow/haul on, through the hill country. Here's what I observed:
City driving to 55, no trailer (on way to get boat) - Temp = 145
Truck sitting while boat hooked up, prepped for tow, etc - Temp = 165 (later dropped back down to 150)
First bit of towing, city, flat up to 55 - Temp = 175
Hit hill country (up & down rolling hills) up to 65 - Temp = 180 - 195
Hit some open highway at 75 - 80 mph - Temp 190 - 200, peaked at 205
I've never worried about anything in the low 200's with my last two Dodge's and I never had any tranny issues, but obviously staying closer to 175 would be better.
Btw, the engine braking was very appreciated.
City driving to 55, no trailer (on way to get boat) - Temp = 145
Truck sitting while boat hooked up, prepped for tow, etc - Temp = 165 (later dropped back down to 150)
First bit of towing, city, flat up to 55 - Temp = 175
Hit hill country (up & down rolling hills) up to 65 - Temp = 180 - 195
Hit some open highway at 75 - 80 mph - Temp 190 - 200, peaked at 205
I've never worried about anything in the low 200's with my last two Dodge's and I never had any tranny issues, but obviously staying closer to 175 would be better.
Btw, the engine braking was very appreciated.
#20
06-09-2009, 05:36 PM
Well, I towed my boat this weekend (4,750 lbs w/ trailer), with tow/haul on, through the hill country. Here's what I observed:
City driving to 55, no trailer (on way to get boat) - Temp = 145
Truck sitting while boat hooked up, prepped for tow, etc - Temp = 165 (later dropped back down to 150)
First bit of towing, city, flat up to 55 - Temp = 175
Hit hill country (up & down rolling hills) up to 65 - Temp = 180 - 195
Hit some open highway at 75 - 80 mph - Temp 190 - 200, peaked at 205
I've never worried about anything in the low 200's with my last two Dodge's and I never had any tranny issues, but obviously staying closer to 175 would be better.
Btw, the engine braking was very appreciated.
City driving to 55, no trailer (on way to get boat) - Temp = 145
Truck sitting while boat hooked up, prepped for tow, etc - Temp = 165 (later dropped back down to 150)
First bit of towing, city, flat up to 55 - Temp = 175
Hit hill country (up & down rolling hills) up to 65 - Temp = 180 - 195
Hit some open highway at 75 - 80 mph - Temp 190 - 200, peaked at 205
I've never worried about anything in the low 200's with my last two Dodge's and I never had any tranny issues, but obviously staying closer to 175 would be better.
Btw, the engine braking was very appreciated.