Ways to monitor trans temp

[Jacob789456]

Hi all, now that my liberty is running and I bypassed the radiator trans cooler and used a Hayden 679 model as a stand alone cooler, I need a way to monitor the transmission temp. I have a scangauge in our Chevy Trailblazer and it is awesome, measures everything including trans temp. However, I read that the scanguage is not very compatible with jeeps. I would like to monitor the trans temp along with coolant temp, and other variables with a digital multi gauge if possible. Are there any options for us for digital all in one gauges or is a mehanical gauge my only option. The libby. is a 2003 with the 45RFE and 3.7 motor. Thanks for any help.

BTW I did search but there was nothing on monitoring fluid temp with other gauges.

 

[tjkj2002]

Run the trans cooler lines back to the in-radiator cooler then loop to the AUX cooler then back to the trans and never worry again.By cutting out the in-radiator cooler you just lost a huge cooling aid for your trans as a stand alone trans cooler is not very good at dealing with temp spikes like the in-radiator cooler is.

 

[k99jk99j]

with the hayden 679 being a stacked plate cooler instead of a tube one, and with it having a rating of 10,000 lbs, i would say you will be fine with temps. but you won't know for sure until you monitor the temp. try b&m's stand alone trans temp guage! mike

 

[LibertyFever]

I've had problems in the past with overheating my transmission so I'm interested in monitoring the temperature too. I have a OBD scanner but it only seems to have the option of monitoring the water temp not the transmission.

I'm thinking of either installing a temperature sensor in the cooling line coming from the transmission with perhaps a T fitting or drilling into the transmission pan and installing a fitting suitable for a temperature sensor. Then running the sensor's output to a gauge.

Why did you bypass the radiator's transmission cooler and add an external one? Is there a problem with the in rad cooler?

 

[Jacob789456]

I bypassed the rad because of horror stories of having the trans cooler mix with coolant, therefore destroying the trans. I also did it because the radiator is aftermarket and sat in the back of the jeep open for 5+ years before it was given to me (was wrecked, totaled, and then given to me after sitting 6+ years). I figured any corrosion build up could weaken the trans cooler and could lead to a high possibility of transmission cooler rupture. If the trans temps are too high I will loop it back through the radiator because the radiator cooler is very efficient at stabilizing trans temps, just not cooling the trans fluid. So what do you guys think are my possible options for a gauge? I am looking in to mechanical gauges but I lover the simplicity of an all-in-one monitoring gauge (Scan Gauge, Bully Dog Gauge, Aeroforce Interceptor,...). Would any digital gauge on the market read the trans temp sensor on these jeeps?

Also to aid the trans cooling with the external cooler I will order and install the clutched fan before summer, and I mounted the cooler in front of the ac-condenser in front of the fans air flow.

 

[Dave]

I think you are stuck to installing a seperate gauge for ****** temp. I have a scangauge in mine and it reads a lot of different gauges but not ****** temp. I wish it did. I think (but not sure) that the ****** temp is just not supported by the PCM.

Dave

 

[huntbuggy]

Am also interested in monitoring trans temp - anyone fitted an inline or t-fitting sensor before the rad cooling inlet hose? Seems the logical place to put it as it's placed in a spot you can work on and would be at the high temp side of the fluid circuit...

An autolite or something directly wired to a sensor seems the simplest, yeah?

 

[J-Thompson]

Not on a KJ but on my TJ
I installed a B&M temp gauge on the return line
as per instructions
found temps to be in the "slightly high" area when off road
I installed an after market cooler on return side then the gauge
I only lost maybe 20* ,running in the 140* area
so on the advice of my "trans guy" I by passed the radiator and went strait cooler
now in July on the trail I may get to 140* ,under lots of load

why was this
simple
the radiator was heating up the trans rather than cooling it
yes it did keep a constant temp but it was constantly high

oh and as to the "temp spikes"
he said
"transmissions that have temp spikes have flow issues
and probably have a plugged cooler or a cooler that is to small"

 

[tjkj2002]

Not on a KJ but on my TJ
I installed a B&M temp gauge on the return line
as per instructions
found temps to be in the "slightly high" area when off road
I installed an after market cooler on return side then the gauge
I only lost maybe 20* ,running in the 140* area
so on the advice of my "trans guy" I by passed the radiator and went strait cooler
now in July on the trail I may get to 140* ,under lots of load

why was this
simple
the radiator was heating up the trans rather than cooling it
yes it did keep a constant temp but it was constantly high

oh and as to the "temp spikes"
he said
"transmissions that have temp spikes have flow issues
and probably have a plugged cooler or a cooler that is to small"

140 is a little low for your trans temp,should be around the 160-175 degree area for best performance.

My TCM locks out OD till the fluid reaches about 140 degrees trying to get the trans temps to normal operating temps.

 

[Neb1373]

Scangauge Measures trans temp? I have the sg II and I have not seen anything on trans temp. My sg II works real well with my 06 kj. Still curious on my map. The numbers seem to be off but I don't know.

 

[LibertyFever]

My Autel MaxiTripp "scangauge" doesn't show the transmission temp. I assumed it was due to the "scangauge" but it may be due to the PCM.

tjkj2002 makes a good point. It may sound like a good idea to run as cool as possible but an engine & transmission must run at an operating temperature to perform the best.

 

[J-Thompson]

140 is a little low for your trans temp,should be around the 160-175 degree area for best performance.

My TCM locks out OD till the fluid reaches about 140 degrees trying to get the trans temps to normal operating temps.

You dont have a TF999

but I still call BS
our 45RFE would hit OD when the temps are well below 35*
and we are less than 2 minutes drive to the highway
start Jeep
back out of drive way
2 stop signs
55mph posted speed ,65 is the norm

"Heat kills a trans"
"off roading generates heat"

 

[tjkj2002]

You dont have a TF999

but I still call BS
our 45RFE would hit OD when the temps are well below 35*
and we are less than 2 minutes drive to the highway
start Jeep
back out of drive way
2 stop signs
55mph posted speed ,65 is the norm

"Heat kills a trans"
"off roading generates heat"

Yeah mine goes into OD,even at -35 but it takes some time and enough heat in the trans before it will,same goes for all Chrysler electronic trans.Your issue was not being geared right if your seeing high trans temps while off roading and/or piss poor cooling system(all 4.0's have piss poor cooling systems to begin with).

And yes heat kills trans but so does operating them to cold.Older fully hydrualic trans(C4/C6,Turbo 350/400,727's,and power glides) required much cooler fluid temps in the range of 150-160 for best operation and longevity.Modern electronically shifted trans can take more heat and require it for proper operation,there range is 170-190 degrees and hence the full synthetic fluids pretty much standard in all trans now.

 

[J-Thompson]

Yeah mine goes into OD,even at -35 but it takes some time and enough heat in the trans before it will,same goes for all Chrysler electronic trans.Your issue was not being geared right if your seeing high trans temps while off roading and/or piss poor cooling system(all 4.0's have piss poor cooling systems to begin with).

And yes heat kills trans but so does operating them to cold.Older fully hydrualic trans(C4/C6,Turbo 350/400,727's,and power glides) required much cooler fluid temps in the range of 150-160 for best operation and longevity.Modern electronically shifted trans can take more heat and require it for proper operation,there range is 170-190 degrees and hence the full synthetic fluids pretty much standard in all trans now.

Piss poor cooling system not a gear issue
TF999 built the same as the TF909 only able to handle more torque and has a torque converter lock up
TF909 was used in CJ's
the parts from a 909 and 999 can be swapped
I need cooler temps

note I dont know a bunch about the "modern" auto's

 

[jnaut]

Scangauge Measures trans temp? I have the sg II and I have not seen anything on trans temp. My sg II works real well with my 06 kj. Still curious on my map. The numbers seem to be off but I don't know.

KJ doesn't push trans temp on the OBD port. Simply not available. I was bummed too. I still love my SGII though.

 

[boatnut]

jnaut, I am not so sure that the OBD port does not push trans temps. If you look on the Aeroforce website, they state that the gauge will read trans temp on the liberty. I don't have one though, so I can't verify this.

Any thoughts on using the stock temp sender in the transmission (the one that drives the idiot light), and piggy backing a gauge onto it? Not sure if it would work or not, just an idea....