Best location for E4OD temp sensor?

MtnHaul

Supporting Member
Supporting Member
Joined
Nov 1, 2014
Posts
710
Reaction score
338
Location
California
Yes I know this subject seems to have been beaten to death like the Facet pumps but I've come across conflicting posts from folks who seem to know what they are talking about and I really want to do what I can to prevent damage to the transmission.

So, many folks seem to like the pressure test port.

Some prefer the converter out line.

And of course adding a sensor port to the pan works for others.

Which location would offer the best reading in terms of preventing damage to fluid and/or hard parts? I would rather have a reading that was a little on the high side than one that was a little low unless we're only talking a negligible difference.
 

Nero

HD Diesel nut
Joined
Jan 3, 2022
Posts
2,900
Reaction score
3,135
Location
OR
Best place would be where the temps are the hottest. So tq converter outlet.
 

Cubey

Van dweller
Joined
Oct 18, 2017
Posts
4,344
Reaction score
1,737
Location
USA
The thing about the TC output is that the fluid temperature is only that temperature a matter of seconds, from the time it leaces the TC until it gets cooled. ATF has a time frame for how long it can hold up at higher temperatures, unless we're talking crazy high numbers that shouldn't be happening at all anyway.
 

Cant Write

Full Access Member
Joined
Sep 29, 2021
Posts
930
Reaction score
798
Location
Placerville CO
Measuring only the TC Outlet would give most a good scare!! Or it would me!!

Measuring above in addition to pan temps would give a good indication of cooling ability.

Seems 100F over ambient is where a lot of trans run. The old adage of 170F or cooler is old info as the newer fluids protect just fine at 190-200F. (Or that’s what I read from the experts :dunno)

I have stressed over this a lot back when I had an early built (2007) 6L80. As it had a cracked drum that would bleed/leak with hot fluid. Over 150F I would lose reverse.

So 100F over ambient measured at test port or pan. And change it every 30-50k depending on abuse. that is the mantra I go by. I also pop the hood and look at it and may adlib it in real time.
 

david85

Full Access Member
Joined
Feb 21, 2008
Posts
4,860
Reaction score
1,130
Location
Campbell River, B.C.
One more vote for TC outlet. Mine is just before the inlet to the cooler, so there could be some slight cooling along the cooler line. Most regular driving is barely enough to move the needle (scale starts at 100F). Slow climbing a mountain road showed me the value of using low range to control trans temps. 210F or 220F was not difficult to reach if I wasn't paying attention.
 

gandalf

Senior Member
Joined
Jan 21, 2005
Posts
3,891
Reaction score
1,095
Location
CA &/or Maine
I have the temp probe at the test port on the side of the pan, right where Calvin told me to put it.

If memory serves me correctly, my E4OD runs consistently at 150*F. Of course, I have the largest Tru-Cool transmission cooler I could find. I'd rather have the transmission run a bit cool than overtemp.
 

MtnHaul

Supporting Member
Supporting Member
Joined
Nov 1, 2014
Posts
710
Reaction score
338
Location
California
Thanks fir the replies, and for giving me about the same range of opinions I've been finding. Well since there don't seem to be any failures associated with incorrect temp probe location I guess I can't go too wrong. Perhaps it's time to flip a quarter or ask the magic 8-ball.
 

XOLATEM

Full Access Member
Joined
May 5, 2023
Posts
787
Reaction score
1,006
Location
Virginia... in the brambles
I am in the TC out line camp....I want to know how hot I am getting the fluid in the torque convertor...

That way I can adjust my driving immediately instead of cooking my fluid and TC internals before I notice what is happening...ATF, even synthetic, only has a certain amount of time at extreme temps before it starts to degrade...

I also like the idea of running two guages like @Cubey because I want to monitor the effectiveness of my ATF cooling system...(I hope you are using full synthetic with those temps...)

That way I can add more cooling capacity if I find my driving makes it necessary...

I want to apologize to the guys that want to run the sender screwed into the case...I have to disagree...all I see there is a convienient way to attach the sender and the reading is of limited use...yes, you get a general reading...

But...if you study the hydraulic circuitry you will find that the fluid has plenty of time and heat sink to cool before you get a reading from a case tap...

Mainline pressure has to come from the pump (which picks up from the sump) and flow along the case before it gets to the tap...aluminum, being highly porous, serves as a heat sink and can do a lot of cooling before you get a reading..

...and the pan fluid has the pan surface area to cool, as well... plus...the volume of fluid in the pan will pull the temp down because of that surface area...

A 'modified ' instead of a 'more true' reading from a case tap will give the driver a false sense of security and allow him to work the trans harder than the condition of the fluid will dictate...that is...if you want it to last as long as possible...

That is just my theory...I welcome differing opinions on it...hell...I always like to consult the brain trust we have here...so...if you can refute this...have at it...I am open to learning something new every day...

With the time and trouble and expense of a transmission rebuild and install these days...I want to hedge my bet on keeping it alive as long as possible...

Just my $0.02

This subject has the potential to spark a pretty lively discussion...not quite the same as cupholders...but lively nevertheless...
 
Last edited:

Clb

Another old truck
Supporting Member
Joined
Mar 1, 2013
Posts
5,950
Reaction score
2,397
Location
nannyfornia
Where actual case temp is more critical than the fluid temp seems to be how the fly boys did it back when I was in service....
Fun read...
 

XOLATEM

Full Access Member
Joined
May 5, 2023
Posts
787
Reaction score
1,006
Location
Virginia... in the brambles
Lets see what happens when you install a temp gauge to a cup holder..
I like that idea...if I can find a good used guage...I just might do that...

I would like to find a home-made way to keep my coffee hot...

Let's see...a 12VDC heating element and a thermocouple...

...incorporated with a steel cup fabbed up to fit a common coffee cup...

...or...a ceramic cup with inserts....

Hmm...hmm...

No ! Wait ! tap off of the heater hose and surround the cup with a copper coil....

Hmm.....
 
Top