Transmission Cooling Questions Answered

kdogg · April 29, 2009

I did some research. And it seems that a lot of guys are afraid of trans. temps above 200deg. So was I. This is from the manual which by the way if you register your truck at mygmlink.com you can get the electronic copy of the owners manual, which is searchable. Once you open the .pdf file hit Control-F and enter the search you want.

By the manual, now I feel comfortable with what I have questions about. These newer trucks may be able to withstand a little higher temperature than past trucks. If not, it is all electronically recorded and under warranty.

That is my thought.

TRANS.bmp

kdogg · April 29, 2009

I did some research. And it seems that a lot of guys are afraid of trans. temps above 200deg. So was I. This is from the manual which by the way if you register your truck at mygmlink.com you can get the electronic copy of the owners manual, which is searchable. Once you open the .pdf file hit Control-F and enter the search you want.
By the manual, now I feel comfortable with what I have questions about. These newer trucks may be able to withstand a little higher temperature than past trucks. If not, it is all electronically recorded and under warranty.

That is my thought.

In addition to this post I will not be adding the Aux. Cooler to my truck. I welcome any challenges!

jrrod2004 · April 29, 2009

I did some research. And it seems that a lot of guys are afraid of trans. temps above 200deg. So was I. This is from the manual which by the way if you register your truck at mygmlink.com you can get the electronic copy of the owners manual, which is searchable. Once you open the .pdf file hit Control-F and enter the search you want.
By the manual, now I feel comfortable with what I have questions about. These newer trucks may be able to withstand a little higher temperature than past trucks. If not, it is all electronically recorded and under warranty.

That is my thought.

Any additional heat can be "deadly". The new Dexron VI fluid has been reformulated to withstand the additional tolerances of the 6.2 engine as well as the extra two cogs of the 6L80E. Most guys here would rather not run the temp close to the limit of the higher temp. I personally would rather keep the temp closer to 125 degrees than 195 for the simple fact that it is cheap insurance. As most here know, alot of guys rarely crack that thing called the Owner's Manual so that may have been updated but as with anything, most here are picky on the performance, myself included.

kdogg · April 29, 2009

I did some research. And it seems that a lot of guys are afraid of trans. temps above 200deg. So was I. This is from the manual which by the way if you register your truck at mygmlink.com you can get the electronic copy of the owners manual, which is searchable. Once you open the .pdf file hit Control-F and enter the search you want.
By the manual, now I feel comfortable with what I have questions about. These newer trucks may be able to withstand a little higher temperature than past trucks. If not, it is all electronically recorded and under warranty.

That is my thought.

Any additional heat can be "deadly". The new Dexron VI fluid has been reformulated to withstand the additional tolerances of the 6.2 engine as well as the extra two cogs of the 6L80E. Most guys here would rather not run the temp close to the limit of the higher temp. I personally would rather keep the temp closer to 125 degrees than 195 for the simple fact that it is cheap insurance. As most here know, alot of guys rarely crack that thing called the Owner's Manual so that may have been updated but as with anything, most here are picky on the performance, myself included.

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. The only way to repair the damage now is with an overhaul -- a job which can easily run upwards of on a late model front-wheel drive car or minivan.

As a rule of thumb, every 20 degree increase in operating temperature above 175 degrees F. cuts the life of the fluid in half!

At 195 degrees F., for instance, fluid life is reduced to 50,000 miles. At 220 degrees, which is commonly encountered in many transmissions, the fluid is only good for about 25,000 miles. At 240 degrees F., the fluid won't go much over 10,000 miles. Add another 20 degrees, and life expectancy drops to 5,000 miles. Go to 295 or 300 degrees F., and 1,000 to 1,500 miles is about all you'll get before the transmission burns up.

If you think this is propaganda put forth by the suppliers of ATF to sell more fluid, think again. According to the Automatic Transmission Rebuilders Association, 90% of ALL transmission failures are caused by overheating. And most of these can be blamed on worn out fluid that should have been replaced.

Thanks for the input.

I was worried about my trans. temp getting to 210. It has only happened a few times. I don't think that 125 is a feasable temp as it runs at 175 even during a normal trip to town as stock. This is design. I don't even have 20,000miles on it, so if I change the fluid which should be done anyways, should'nt I be ok under these cercumstances?

96chevy7.4L · April 29, 2009

Hi guys if you are not interested in adding an aux trans cooler. Try this Derale makes cooling tube pans that hold an extra 3 quarts of fluid. They have 1/2 inch cooling tubes that run the long axis of the pan. These pans (and I have one on all my trucks) will reduce your trans temps 20 degrees at a minimum on there own. Sure you have to drop your old pan but a fluid change won't hurt. More fluid circulating is cooler fluid all around. My 1 ton duallys see heavy towing daily. The derale pans and B&M super coolers show 160 trans temps with a 30 foot gooseneck trailer and 10,000 pounds tractors on board. This in FL and GA with 90 degree temps outside. By the way I do run 180 degree thermostats which I am sure aid this a lil but the fact remains 160 degree temps are only helping the matter. Cool fluid means a happy and longer lasting transmission. Just my .02 cents.

brims · April 29, 2009

I did some research. And it seems that a lot of guys are afraid of trans. temps above 200deg. So was I. This is from the manual which by the way if you register your truck at mygmlink.com you can get the electronic copy of the owners manual, which is searchable. Once you open the .pdf file hit Control-F and enter the search you want.
By the manual, now I feel comfortable with what I have questions about. These newer trucks may be able to withstand a little higher temperature than past trucks. If not, it is all electronically recorded and under warranty.

That is my thought.

This is in the owners manual for a GMT900? I have a feeling it isn't since I don't have an actual gauge for trans temp. I don't like the idea of having trans get anywhere near 265. As the max temp out of the trans to the cooler should be 300, if the temperature at the sender unit is 265, your output from the trans to cooler will probably be well above 300.

I've been up and down 2 GMT900 manuals a couple of times and never remember seeing a normal temperature listed. Like others, I would much prefer to stay below 190.

C & A s Dad · April 29, 2009

Kevin, no challenges here concerning you not adding an aux cooler. It is your truck and your $s. However, I think that most agree that 265 would be extreme and for that matter 250 would be too hot. You have also posted the facts about fluid life at temps this high.

I noticed one other thing in the link you posted that would make me question the integrity of this info.

This is a quote from the link you posted:

"A temorary solution to reduce hotter transmission operating temperatures may be to let the transmission cool down"

Wow, I would have never thought of that. The guy that wrote this is obviously educated beyond his intelligence.

Kevin, not picking on you, just the info in the manual.

Volucris · April 29, 2009

I did some research. And it seems that a lot of guys are afraid of trans. temps above 200deg. So was I. This is from the manual which by the way if you register your truck at mygmlink.com you can get the electronic copy of the owners manual, which is searchable. Once you open the .pdf file hit Control-F and enter the search you want.
By the manual, now I feel comfortable with what I have questions about. These newer trucks may be able to withstand a little higher temperature than past trucks. If not, it is all electronically recorded and under warranty.

That is my thought.

This is in the owners manual for a GMT900? I have a feeling it isn't since I don't have an actual gauge for trans temp. I don't like the idea of having trans get anywhere near 265. As the max temp out of the trans to the cooler should be 300, if the temperature at the sender unit is 265, your output from the trans to cooler will probably be well above 300.

I've been up and down 2 GMT900 manuals a couple of times and never remember seeing a normal temperature listed. Like others, I would much prefer to stay below 190.

Well, it's the owners manual for a GMT800. The transmission temperature guage is an option, it probably comes with the HD towing package. I don't have on either, that's why I got a scan guage. Works well.

kdogg · April 29, 2009

I did some research. And it seems that a lot of guys are afraid of trans. temps above 200deg. So was I. This is from the manual which by the way if you register your truck at mygmlink.com you can get the electronic copy of the owners manual, which is searchable. Once you open the .pdf file hit Control-F and enter the search you want.
By the manual, now I feel comfortable with what I have questions about. These newer trucks may be able to withstand a little higher temperature than past trucks. If not, it is all electronically recorded and under warranty.

That is my thought.

This is in the owners manual for a GMT900? I have a feeling it isn't since I don't have an actual gauge for trans temp. I don't like the idea of having trans get anywhere near 265. As the max temp out of the trans to the cooler should be 300, if the temperature at the sender unit is 265, your output from the trans to cooler will probably be well above 300.

I've been up and down 2 GMT900 manuals a couple of times and never remember seeing a normal temperature listed. Like others, I would much prefer to stay below 190.

Well, it's the owners manual for a GMT800. The transmission temperature guage is an option, it probably comes with the HD towing package. I don't have on either, that's why I got a scan guage. Works well.

This is from my trucks manual. Like I said the electronic copy. I have an 07 NBS. It does have a trans temp sensor, but you can only see the reading if you have the DIC installed. If not, the sensor is still there you just can't see it. The quote from above mentions to let it cool down because it got over 265 wich means something is seriously wrong. That's what temperary ment. Not to keep driving it if possoble.

So, over all, I get the point that cooler temp is a good thing. I think if I don't see temps over 210 I'll be fine.