[bryan340]

Any of you guys mount your tranny temp sensor in the test port near the dipstick. Diesel manor shows it in the port towards the rear of that one.Problem is, in that one you need an extender, the sender bottoms out. I have it in now and it reads 151 degrees under normal driving. THANKS

 

[scott116]

I have mine in the same place, and reads about 150 under normal driving also.

 

[SEAN06]

same for me also.:thumbsup:

 

[cerberusiam]

Any of you guys mount your tranny temp sensor in the test port near the dipstick. Diesel manor shows it in the port towards the rear of that one.Problem is, in that one you need an extender, the sender bottoms out. I have it in now and it reads 151 degrees under normal driving. THANKS

WRONG! WRONG! WRONG! WRONG!

Its a TEST port not a sensor port. As you see without the extension you will trash the trans mission as there is a piston behind that port.

Test ports are dead end and have no flow, all it will read is heat soak in the trans. Trans temp sender goes in the output cooler line so you can use it to drive by.

 

[Cummins600]

That's how I mounted mine...got the replacement line from MASS Diesel. I checked and I wasn't correct. It is the cooler line, but not the return. It's the cooler supply....so coming out of the trans.

 

[05HDRAM]

WRONG! WRONG! WRONG! WRONG!

Its a TEST port not a sensor port. As you see without the extension you will trash the trans mission as there is a piston behind that port.

Test ports are dead end and have no flow, all it will read is heat soak in the trans. Trans temp sender goes in the output cooler line so you can use it to drive by.

I disagree. I have mine in the test port for 5 years now (basically since new), and never had any issues. The trans fluid does not flow in Park, that is the only time the port would be dead.

My temp is usually around 130 to 140 in 70 degree weather. When the outside temps go into the 80's and 90's, trans goes to 160 to 180 depending on traffic. I have compared my readings to those that use the hotline, and they are very close. Yeah I may be reading 10 degrees cooler, but I don't use the temp as absolute, I use it to know if I am heating up the tranny too much. It's no different that using the stock coolant temp or oil pressure gauges in my opinion.

 

[RiotAct]

...but I do know that the cooler is working and the temp of the fluid going back to the trans.

Wow. That's a great way to monitor your tranny temp.

Tranny fluid starts breaking down at about 225*. If you're constantly running around 250*, things will start falling apart quicker than Mel Gibson after a 3 day drinking binge. Monitoring your fluid on the cool side doesn't tell you much.

Get the kit from dieselmanor for about $70 that allows you to tap into the hot side.


Riley~~~

 

[snowman475]

can someone explain exactly which test port to use ?
thanks !

 

[cerberusiam]

The trans fluid does not flow in Park, that is the only time the port would be dead.

I have compared my readings to those that use the hotline, and they are very close. Yeah I may be reading 10 degrees cooler, but I don't use the temp as absolute,

The port is dead all the time, there NO fluid flow thru the front servo as its a dead end. Thats the way servos work.

Your not using the gauge at all and have never tried it in circumstances where it will make difference then. Put 10k behind the truck then start doing stop and go slow speed driving or pull a 10% grade at 35 mph into a campground. You will see a difference that can be 100 degrees or better.

Tranny fluid starts breaking down at about 225*. If you're constantly running around 250*, things will start falling apart quicker than Mel Gibson after a 3 day drinking binge.

Yeah, 20 years ago that may have been true but no longer. ATF+4 is rated at 320 degrees for 1500 hours and still meet ISO standards.

Operating temp on the 48RE is 140-240 degrees, the over temp thermistor is set to kick on at 260. The fluid can handle more temp but extended high temps tends to cause seals and frcitions to start breaking down in the trans.

can someone explain exactly which test port to use ?
thanks !

You don't use a test port ever, its a waste of the gauge and the $$ for it, plus it tells you nothing useful. Either get the cooler output line or Genos garage has a fitting that will go in the rubber part of the output line. You need to monitor the temp in the cooler output line to manage your driving.

 

[RiotAct]

Operating temp on the 48RE is 140-240 degrees, the over temp thermistor is set to kick on at 260.

I pulled Pike's Peak last month (14,110' above sea level) and briefly showed 280* on the gauge (its a series of switchbacks driving up there and you sometimes have to wait a minute or two to find a spot to pull over, cool off and let traffic by). I never noticed any lights or anything change @ 260*. What does this over temp thermistor do?


Riley~~~

 

[cerberusiam]

I pulled Pike's Peak last month (14,110' above sea level) and briefly showed 280* on the gauge (its a series of switchbacks driving up there and you sometimes have to wait a minute or two to find a spot to pull over, cool off and let traffic by). I never noticed any lights or anything change @ 260*. What does this over temp thermistor do?
Riley~~~

When the ECU finally decides the trans is over temp it knocks it out of OD and allows lockup to hit sooner.

The ECU reads things and smoothes them so you don't get potential flase alarms. Its is not unusual that you would hit 280 in the pan and no alarms. If you sensor is in the hot line the sensor will never see that because the fluid is cooled before it returns.

 

[2500 Cummins]

The port is dead all the time, there NO fluid flow thru the front servo as its a dead end. Thats the way servos work.

Your not using the gauge at all and have never tried it in circumstances where it will make difference then. Put 10k behind the truck then start doing stop and go slow speed driving or pull a 10% grade at 35 mph into a campground. You will see a difference that can be 100 degrees or better.



Yeah, 20 years ago that may have been true but no longer. ATF+4 is rated at 320 degrees for 1500 hours and still meet ISO standards.

Operating temp on the 48RE is 140-240 degrees, the over temp thermistor is set to kick on at 260. The fluid can handle more temp but extended high temps tends to cause seals and frcitions to start breaking down in the trans.




You don't use a test port ever, its a waste of the gauge and the $$ for it, plus it tells you nothing useful. Either get the cooler output line or Genos garage has a fitting that will go in the rubber part of the output line. You need to monitor the temp in the cooler output line to manage your driving.

Very well said. :thumbsup:

 

[NavyDood]

I pulled Pike's Peak last month (14,110' above sea level) and briefly showed 280* on the gauge (its a series of switchbacks driving up there and you sometimes have to wait a minute or two to find a spot to pull over, cool off and let traffic by). I never noticed any lights or anything change @ 260*. What does this over temp thermistor do?


Riley~~~

The temps on the output line are before the fluid goes thru both coolers. It is cooling down before it goes back to the tranny. That is why you never got the dash light.

The temp thermistor is part of the governor pressure sensor assembly and is immersed in transmission fluid at all times.

Like Cerb said... If fluid temperature exceeds 260°F, the PCM causes a 4-3 downshift and engage the converter clutch. Engagement is according to the third gear converter clutch engagement schedule. The Tow/Haul lamp in the instrument panel illuminates when the shift back to third occurs. The transmission
will not allow fourth gear operation until fluid temperature decreases to approximately 230°F.

 

[RiotAct]

The temps on the output line are before the fluid goes thru both coolers. It is cooling down before it goes back to the tranny. That is why you never got the dash light.

The temp thermistor is part of the governor pressure sensor assembly and is immersed in transmission fluid at all times.

Like Cerb said... If fluid temperature exceeds 260°F, the PCM causes a 4-3 downshift and engage the converter clutch. Engagement is according to the third gear converter clutch engagement schedule. The Tow/Haul lamp in the instrument panel illuminates when the shift back to third occurs. The transmission
will not allow fourth gear operation until fluid temperature decreases to approximately 230°F.

Ah, gotcha. I was using 1-2 gears the whole way up. Would it have made a difference putting the tow/haul mode on? The convertor luckup only engages in 3rd gear right?


Riley~~~

 

[cerberusiam]

Ah, gotcha. I was using 1-2 gears the whole way up. Would it have made a difference putting the tow/haul mode on? The convertor luckup only engages in 3rd gear right?


Riley~~~

Not on your truck, TH is just an OD lockout.

The trans will lock in manual second but you can't be pushing the truck hard under very much to do it. The standard ECU controlled lockup is about useles unless your on the flat. However, a lockup switch would halped you there. These units will lock in 1st and 2nd if you over ride the ECU. Locked up your temps would have been much closer to normal as long as you could maintain airflow thru the coolers in front.

 

[05HDRAM]

The port is dead all the time, there NO fluid flow thru the front servo as its a dead end. Thats the way servos work.

Your not using the gauge at all and have never tried it in circumstances where it will make difference then. Put 10k behind the truck then start doing stop and go slow speed driving or pull a 10% grade at 35 mph into a campground. You will see a difference that can be 100 degrees or better.


You don't use a test port ever, its a waste of the gauge and the $$ for it, plus it tells you nothing useful. Either get the cooler output line or Genos garage has a fitting that will go in the rubber part of the output line. You need to monitor the temp in the cooler output line to manage your driving.

Hmm, wonder why I see the similiar temp changes as those with the hotline or the probe in the pan. If you were correct, I should see no fluctuation in temps. And then there was the 20 degree drop I saw when I changed my fluid. What is your explanation for the changes I see if the port is dead ?

I am not going to tell anyone to use the test port, I agree it is not the best option. I planned on getting a new hotline to move the probe, but I have not had any issues in 5 years so it is still there. Maybe I am just lucky my tranny has not melted, or maybe I am getting close enough readings to know when to let it cool off. We may never know.

 

[NavyDood]

Hmm, wonder why I see the similiar temp changes as those with the hotline or the probe in the pan. If you were correct, I should see no fluctuation in temps. And then there was the 20 degree drop I saw when I changed my fluid. What is your explanation for the changes I see if the port is dead ?

I am not going to tell anyone to use the test port, I agree it is not the best option. I planned on getting a new hotline to move the probe, but I have not had any issues in 5 years so it is still there. Maybe I am just lucky my tranny has not melted, or maybe I am getting close enough readings to know when to let it cool off. We may never know.

How fast are you seeing the temp changes? My temp will be 150°F on the out line going down the highway. As soon as I stop at a stop light, I can literally see the tranny temp start to creep up in temp, increasing 10°F-20°F just sitting there. As soon as I start moving it will start coming back down within a mile or two.

 

[cerberusiam]

Hmm, wonder why I see the similiar temp changes as those with the hotline or the probe in the pan. If you were correct, I should see no fluctuation in temps. And then there was the 20 degree drop I saw when I changed my fluid. What is your explanation for the changes I see if the port is dead ?

I don't know how and when these temps were recorded and what the conditions were so its hard to tell what you are seeing along with what others are seeing.

Lets look at the temps you posted and I will compare to mine in the hot line.

My temp is usually around 130 to 140 in 70 degree weather

When the engine is up to operating temp and the trans is fully warmed I see 170-190 from 60 degrees to 110 degrees. This is in lockup, no load, rolling down the road with decent air flow thru the coolers. Your reporting 50-60 cooler than what I and least 5 others with the probes in the hot line typically see, given the conditions I specified.

When the outside temps go into the 80's and 90's, trans goes to 160 to 180 depending on traffic

Under these same conditions and am assuming stop light to stop light type of driving with some idling at the lights, its no unusual to see 220 degrees at the cooler output.Mine is a little cooler because I have a good TC, others have reported seeing 230-240 in the same conditions. I have seen 260 degrees with a heavy trailer and too much traffic that cause speed up\slow down type of driving. In-trans temps will probably never break 200 degrees under these conditions.

Your temps are low because the test ports are not in the main flow of fluid, they will only report the total trans temp or heat soak it achieves. The temps I read take into account whether the TC is locked or unlocked and how much I am loading things to generate heat.

The TC generates over 90% of the heat in the trans, why would NOT want to read it as close as possible to adjust driving? Like I have said before, the hot line gives the ability to be pro-active instead of re-active to trans temps. I have never had to pull over on a grade with any load because my trans temps got to hot, I cna djust gears and lockup on the fly to make sure it never happens.

 

[Cummins600]

Wow. That's a great way to monitor your tranny temp.

Tranny fluid starts breaking down at about 225*. If you're constantly running around 250*, things will start falling apart quicker than Mel Gibson after a 3 day drinking binge. Monitoring your fluid on the cool side doesn't tell you much.

Get the kit from dieselmanor for about $70 that allows you to tap into the hot side.


Riley~~~

Sorry. Edit to my post as I stated incorrectly. Bought mine from Mass Diesel, but otherwise the same thing.

Nevertheless, the line is the way to go. I can't say that I've seen temps that high though when on Pikes Peak. I only live about 40 miles away and have gone up a few times. Maybe the built trans has something to do with it.

 

[snowman475]

You don't use a test port ever, its a waste of the gauge and the $$ for it, plus it tells you nothing useful. Either get the cooler output line or Genos garage has a fitting that will go in the rubber part of the output line. You need to monitor the temp in the cooler output line to manage your driving.

thanks !
line ordered from Mass Diesel. :beer