I've searched the archives on this site and the TDR. I've asked Geno's and ATS. I'm more confused than ever.

I started by thinking "in the pan". This is what Geno's and ATS recommend. But I didn't like the idea of needing to pull the pan on a brand new truck. So I started looking.

Many use a test port, ATS agrees that this works well. Seems easy enough and straightforward. But others on the forums say it's not a good sample.

There is a third camp that says use the cooler line. I've even seen posts that say that this is the ONLY place to measure. The other options aren't accurate enough. It's the hottest point to measure the fluid. Gives the best indication of overheating. Mass diesel sells a cooler line for this purpose. ATS and Geno's recommend against this.

Right now I'm thinking of just passing until the first trans fluid service, getting the mag-hytec pan and doing it then. I'm not planning on towing heavy (<7000lbs) and the gauge was more just for of keeping an eye on the 48RE.

But part of me thinks the cooler line sounds like a great spot, the reasons make sense. But why then does Geno's and ATS recommend against it.

I keep going in circles over this..

Thoughts?

 

I am no expert, but like everyone, I have opinons.
I think the cooler line is the best place if you want to spend the money.
I took the cheaper and simpler way. The test port.
I know what I normally read, so I will be able to see if it gets above normal even though it may not be exact.
IF...I say IF I get a Mag-Hytec pan someday, I will probally move it to the pan.

 

Steven,

I'm debating this issue too.
I'm leaning toward the pan sensor. To me it's not valid to rule this option out simply because you have to pull the pan. That has nothing to do with it being the right place functionally, and the pan will soon be off anyway. While I agree that the cooling line will show the hottest oil and show it quickly, I'm wondering if we'd be overanalyzing the temp readings all the time and backing off for every temp spike. If ATS is happy with the average temp that the pan shows, especially on a tranny that is made for hard work, then the average must be OK. I don't know about the test port, is it just an easy way out?

Wetspirit

 

I don't know if it works on the 03's, but on my 01, I bought the trans cooler line from Dodge with the test port built into it. It measures the temp of the fluid coming from the TC and going into the cooler. It's the most accurate. The line cost me $108.

 

For what its worth I had the recall on the tranny line and I put my own port in it for the sensor and had a hard time getting a ground so it would read. I ended up using a test port on the passenger side of tranny and it reacts fast and I think I will keep it there.

JIm

 

To me it's not valid to rule this option out simply because you have to pull the pan. That has nothing to do with it being the right place functionally, and the pan will soon be off anyway.

Right. If I took this route I'd wait til I needed the first fluid change. I don't like doing the trans service myself. And the $100 or so extra it would cost to install the new pan and dump brand new trans fluid down the drain... Well I'd just then wait til it needed a service and install the sending unit then. I wonder if the dealer would mind installing the mag-hitec pan...

While I agree that the cooling line will show the hottest oil and show it quickly, I'm wondering if we'd be overanalyzing the temp readings all the time and backing off for every temp spike.

Agreed. But OTOH the idea is that if you're really overworking it, you'll know it sooner. Back off sooner.

If ATS is happy with the average temp that the pan shows, especially on a tranny that is made for hard work, then the average must be OK.

Yup. But other trans shops on the TDR said that the cooler was the only way to go.

Is putting a trans temp gauge on for the weights I'd haul "overanalyzing" to start with?

I don't know about the test port, is it just an easy way out?

Depends on who you ask. Some say ya. The TDR posts that lead me to think the cooler line was the way to go said the trans shop said most all the failed units they saw had the sender mounted here. But ATS said it was OK. Others have used it with success. If you're looking for an average fluid temp it should work just as well I'd think.

 

Steven, I went through the same as you - finally decided on the test port.

My not be as accurate - but it is giving me a general idea. Easiest solution for me.

 

I think the confusion comes from the fact that folks are equating the 48RH trannies on the '04s with the earlier 47RH.
On the 47 the test ports weren't good at all for temps, on the 48 my understanding is the test port temp is the same as the output line to the cooler.

 

I took a look at the '03 service manual. It seems the port people are using is the accumulator test port? Is anyone better at reading these diagrams than I? It seems that it only gets flow in some scenarios.

 

Just a question, I was going to put in a tranny temp gauge a few days ago when the women took me there is a idiot light that says tranny temp, I looked and sure enought when you start the truck on the left side of the cluster there is a light that comes on that says in red letters trans temp. Would this idiot light be forwarning enough, to do with out the gauge?
Heath

 

I recently installed mine and it went directly into the 1/8" NPT plug for the governor test port. I got this idea from another thread on this board and the thread mentioned it was the only port-w-fluid going to it all the time. I get temp readings all the time as well. I did have to extend the probe wires. Another bit of trouble I had was the threading on the probe which was not tapered and did not readily go into the plug hole. I tapped the hole deeper and it was OK.

 

ARAcummins,

The light comes on at ~255F. Which by most peoples standards is when the trans is already toast.

I'll probably do the governor test port and maybe move it to the pan after the first change.

 

From ATS:

 

I used the cooler line from Mass Diesel.

 

Don't count on that light coming on. I had mine up to 260 once and it never once flashed.