DIC trans warning temp barrier?

[03Cobra]

At what temperature does the DIC indicate a trans temp warning? I have an 07 Silverado CC 5.3L, auto.

[GM-Tech]

It says, "Transmission hot idle engine" but I can't find any information on the temp required before this is displayed. I'll keep looking.

[C & A s Dad]

Someone told me the first warning to idle engine comes on at 250 degrees and then another more seriouls warning comes on at 275 degrees. Not sure where I read it so I cannot promise it is accurate, however, I think it was in this forum somewhere.

 

I do know that dino trans fluid cannot take 250 degrees for long. Of course your '07 should have the new syn Dexron. Anyway, you do not want your trans at or near 250 for long. I do not want mine there even for a minute if I can help it.

 

Are you using the truck to tow and does it have an aux trans cooler from the factory?

[GM-Tech]

I looked through the list of possible DIC messages and only saw one possible message for a hot trans. Of course it didn't tell me at what temp that is displayed.

[03Cobra]

Someone told me the first warning to idle engine comes on at 250 degrees and then another more seriouls warning comes on at 275 degrees. Not sure where I read it so I cannot promise it is accurate, however, I think it was in this forum somewhere.

 

I do know that dino trans fluid cannot take 250 degrees for long. Of course your '07 should have the new syn Dexron. Anyway, you do not want your trans at or near 250 for long. I do not want mine there even for a minute if I can help it.

 

Are you using the truck to tow and does it have an aux trans cooler from the factory?

 

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Yeah, I'll be towing about 5,800# ocassionally. I'm getting a TCI tran pan that hold 3.3 extra quarts. Standard tow rating is 6,600 and max is 7,700 so I should be fine with stock cooler and larger pan.

[C & A s Dad]

Paul, you should be fine with your tow weight. Personally, I would opt for a larger cooler instead of the pan. I have nothing against the deeper pan but upgrading the cooler is a pretty easy job. I replaced my OE cooler with the same stacked plate design but used one about twice as large. Not sure what part of the country you live in and you would not want to do this if you live in a very cold climate.

[pm26]

If one upgrades to a larger cooler and does not tow that often, is it possible to overcool the transmission oil? There is no thermostat controlling the oil temperature, and too efficient a cooler may not always be the best.

[GM-Tech]

If one upgrades to a larger cooler and does not tow that often, is it possible to overcool the transmission oil?

 

Yes, and this is why the added on trans cooler should always be installed in series with the cooler in the radiator.

[C & A s Dad]

GM Tech, I guess I never thought about anyone bypassing the cooler in the radiator. I would always recommend the aux cooler be installed behind the internal trans cooler, meaning the fluid runs from the trans too the internal cooler, to the aux cooler and then back to the trans. This is the way the factory OE coolers come installed.

 

Where I live I do not have to worry about overcooling but I can see where this would be an issue in cold climates.

 

Also, the stacked plate coolers that I have seen have a built in regulation system. When the fluid is cold and thick, it follows a more direct path through the cooler and does not flow through all of the fins. As the fluid warms and thins, it begins traveling into the entire cooler. Maybe not a perfect "thermostat" but it does seem to be effective.

 

I am not saying that the following statement is true but my Dad is personal friends with an owner of a Coleman Taylor trans franchise. He is in his 60s and has owned this trans shop for almost 30 years. I talked to him at length before I upgraded my cooler. He said it is all but impossible to overcool a trans in our part of the country. He said they do have to get warm but there is no benefit in a trans reaching temps close to 200 degrees. He owns a mid 80s El Camino with over 200K on the original trans. He has a very large aux cooler on it and said it has never seen 150 degrees. I have read some opinions that say a trans must reach a certain temp to "boil off" the impurities and moisture. He said there is no combustion in a trans like an engine and it is sealed, unlike an engine that is "breathing in" some pretty nasty air and burning some nasty fuel which leaves things behind. What he says seems to make sense to me. Any thoughts?