Scangauge2 tranny and water temp

nbenjamin

Original poster
Member
Dec 7, 2011
76
Installed a Scangauge2 very nice unit . I can now tell that my heater plug does work when i plug it in . My main reason was for transmission temp . I have a sensor mechanical gauge . But i noticed the SG2 does not note a difference is tran temp from my original setup when i stop at idle after coming off highway etc .Where does the OBD2 sense tran temp from ? because my sensor is on the line coming from tran to RAD . I am just curious which is indicating a true tran temp ? SG2 or my setup ?
What is the proper running tran temp ? I noticed being winter with my cooler and no towing i run around 100-115 f , my water temp shows 100 deg c , I wonder if i am doing damage by running transmission at such a low temp .
 

Wex

Member
Dec 4, 2011
124
I have always assumed that SG2 got its tranny temp from a sensor perhaps in the valvebody?

It takes a while for my transmission to come upto the 190-200 temp. Sometimes as long as 40+ miles on the freeway in the winter.

I feel comfortable if it is at least 160+. but sometimes it will not reach that doing a short hop to a neighboring neighborhood or quick run to an atm.
 

nbenjamin

Original poster
Member
Dec 7, 2011
76
Wex said:
I have always assumed that SG2 got its tranny temp from a sensor perhaps in the valvebody?

It takes a while for my transmission to come upto the 190-200 temp. Sometimes as long as 40+ miles on the freeway in the winter.

I feel comfortable if it is at least 160+. but sometimes it will not reach that doing a short hop to a neighboring neighborhood or quick run to an atm.


Do you have a tranny cooler installed ?
 

Wex

Member
Dec 4, 2011
124
nbenjamin said:
Do you have a tranny cooler installed ?

No, I do not have one installed. It is fully stock oem cooling on my vehicle. Once the 100+ summer rolls around, my transmission will reach normal 195ish-210 temps in around 20 or so miles. Highest I ever seen was around 220. It was hot outside and gridlocked 20+ mins in bumper to bumper traffic. Took about 20 miles at 60Mph to get it back to 210.
 

nbenjamin

Original poster
Member
Dec 7, 2011
76
I am wondering if i should take the one i have out and install one that bi-pass fluid when its too cold ?
 

Wex

Member
Dec 4, 2011
124
nbenjamin said:
I am wondering if i should take the one i have out and install one that bi-pass fluid when its too cold ?

Maybe you could temporarily block airflow through your external transmission cooler during extreme cold.
 

Bartonmd

Member
Nov 20, 2011
545
nbenjamin said:
Installed a Scangauge2 very nice unit . I can now tell that my heater plug does work when i plug it in . My main reason was for transmission temp . I have a sensor mechanical gauge . But i noticed the SG2 does not note a difference is tran temp from my original setup when i stop at idle after coming off highway etc .Where does the OBD2 sense tran temp from ? because my sensor is on the line coming from tran to RAD . I am just curious which is indicating a true tran temp ? SG2 or my setup ?
What is the proper running tran temp ? I noticed being winter with my cooler and no towing i run around 100-115 f , my water temp shows 100 deg c , I wonder if i am doing damage by running transmission at such a low temp .

The SG2 (and ECM) measure temperature somewhere in the valve body, which is basically sump temperature. Your original gauge measuring flow out of the transmission, to the cooler, is a good one to keep, as well! Trans fluid is degraded by time at temperature, and it is the hottest when it comes out of the torque converter, and goes to the cooler. It you're pulling heavy (especially with the really loose converter on the I6 models), and have a big cooler, you sump temperature could be just fine, but your torque conver output temperature could be through the roof, and you wouldn't know it unless you had a temp gauge there. They are both indicating true temperature, but the SG2 is indicating average sump temperature, and the cooler line gauge is indicating trans fluid temperature coming out of the converter, or what is really "max" temperature that it sees in a cycle.

100F is way too cold for a transmission to live its life. Optimum design temperature is between 160F and 220F, and the fluid will last the longest if it stays between 160F and 200F. It's harder on the transmission when the fluid is colder, because it's thicker, and hits pistons and valving harder, etc... I had a too large standard cooler on my Caprice for a while, and if I went a month or so without it getting to 140-160F, it would start having problems with condensation freezing inside the transmission, and locking up the converter clutch soleniod, and other such items. I'd run it hard in town and get it above 160F, and it would be fine for another month or so, until more water vapor built up in it.


nbenjamin said:
I am wondering if i should take the one i have out and install one that bi-pass fluid when its too cold ?

In Canada, yes!

Mike
 

nbenjamin

Original poster
Member
Dec 7, 2011
76
Bartonmd said:
The SG2 (and ECM) measure temperature somewhere in the valve body, which is basically sump temperature. Your original gauge measuring flow out of the transmission, to the cooler, is a good one to keep, as well! Trans fluid is degraded by time at temperature, and it is the hottest when it comes out of the torque converter, and goes to the cooler. It you're pulling heavy (especially with the really loose converter on the I6 models), and have a big cooler, you sump temperature could be just fine, but your torque conver output temperature could be through the roof, and you wouldn't know it unless you had a temp gauge there. They are both indicating true temperature, but the SG2 is indicating average sump temperature, and the cooler line gauge is indicating trans fluid temperature coming out of the converter, or what is really "max" temperature that it sees in a cycle.

100F is way too cold for a transmission to live its life. Optimum design temperature is between 160F and 220F, and the fluid will last the longest if it stays between 160F and 200F. It's harder on the transmission when the fluid is colder, because it's thicker, and hits pistons and valving harder, etc... I had a too large standard cooler on my Caprice for a while, and if I went a month or so without it getting to 140-160F, it would start having problems with condensation freezing inside the transmission, and locking up the converter clutch soleniod, and other such items. I'd run it hard in town and get it above 160F, and it would be fine for another month or so, until more water vapor built up in it.





In Canada, yes!

Mike




thank you for the info . I noticed the inline gauge is always inverse to the SG2 , the SG maxes at 115f and the inline maxes at about 140-150 , thats if im stuck in traffic etc .

I think i may just block the cooler for now and in the summer install a new one . whats a good one or name brand that has the bi-pass i thought they were all designed with some form of thermal bi-pass , guess not .
 

Bartonmd

Member
Nov 20, 2011
545
nbenjamin said:
thank you for the info . I noticed the inline gauge is always inverse to the SG2 , the SG maxes at 115f and the inline maxes at about 140-150 , thats if im stuck in traffic etc .

I think i may just block the cooler for now and in the summer install a new one . whats a good one or name brand that has the bi-pass i thought they were all designed with some form of thermal bi-pass , guess not .

They are NOT all designed with a thermal bypass. I'm not into them enough to tell which one is best or whatever.

Mike
 

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