Engine/Transmission (1998.5 - 2002) Auto trans test ports for temp sensor?

[Allnew2Me]

I just installed all my guages and have only to install the transmission temperature sender unit on the trans itself. I noticed that there are four 1/8"

NPT plugs on the drivers side of the 47RE that are the same thread/size as my Autometer sender and after looking in the shop manual I see that they are pressure test ports for checking the various line pressures in the trans. They are for checking the pressure on the rear servo, governor, accumulator, and front servo. My question is are these a good location for the temp sender? Is there anything inside that would conflict with the sender unit? Also, what is the fluid flow past these various areas in the trans, is the fluid going to the coolers or returning? I will drill and install in the pan if needed but these ports would be perfect in that they are up on the trans out of the way and are already drilled and tapped. Thanks for any info on this.

 

[mjendrejcak]

I had my autometer gauge installed the same way you are thinking. I had to get an adapter because the sending unit would bottom out in the trannie before I got 3 -4 threads in.



This is not the best place in my opinion and many others on this site for the temp gauge. This weekend I had 2 yards of wet topsoil in the bed and a big skid steer on a tag trailer, trannie never went over ~120 while boost was maxed and EGT was a steady 1100 pre. I imaging I was a little higher than 120 degress with 75+ outside temp.



After a search on this site I found many\most people tap or replace the line heading to the trannie cooler and report more acurrat temps.



I'll be makeing this change myself before next big tow.

 

[rweis]

Go to the DTT web site and read the info on why NOT to put the transmission temp sensor in the test ports. Those guys do know their transmission's and have good info on the site.



Bob Weis

 

[fox]

Those ports will only allow pressure measurements. There is only a little flow to them and no flow accroos them, so they are not any good for temp measurements. The best place is nearest the source of heat, and that is the converter/ oilcooler line.

 

[R-N-R]

Go to the DTT web site and read the info on why NOT to put the transmission temp sensor in the test ports. Those guys do know their transmission's and have good info on the site.



Bob Weis

Here you go!

Where to install the transmission temp sensor is one of the most frequent question and discussions I have with guys. My question to you guys is this, why are you buying a gauge?



If you are buying a transmission temp gauge just so you have one and you can tell your friends you have one then you can pretty much put it wherever you want, as it really doesn’t matter in that case.



To me, a gauge is there to monitor transmission temps and indicate how often to change the oil. If you want a gauge for what I consider to be its primary functions then lets look at the oil. Oil temp is what we are trying to monitor so keeping that in mind lets look at the common places people install their gauges and what they are learning by doing so. Decide for yourselves where you want to monitor your transmission temps from and at what cost.



First lets deal with when and why transmission oil gets hot. Most will agree that trans temps are the hottest in stop and go traffic when the transmission is in first or second gear or in the reverse position, in most cases when trying to back up a trailer.



One of the favourite locations by people is the front servo on the passenger side of the transmission. The problem with that is there is no oil in that port in first gear, 2nd gear, or reverse so what are you measuring?

If you do have a transmission temp sensor in that port, take it out, not only is it not monitoring your oil it is probably causing damage to the transmission as the probe is most likely making contact with the servo spring.



Middle port passenger side better known as accumulator port is another, while this port does measure transmission temp in first, second, drive and od, it is measuring stagnant oil. It other words oil fills up and stays there. There is no oil present in the accumulator while you are in the reverse position. So it is useless to measure from this location also.



Another favourite place is in the reverse port on the passenger side. This port only has oil in the reverse and manual low positions. This means no oil in the in the drive position. I have had guys phone me arguing with me that they are seeing temps of 200 degrees while driving down the road in stop and go traffic when measuring from this port. My comment to that is congratulations we now know the temps of your transmission case, we can only guess at this point what your transmission temps are.



As far as I am concerned, there is only one location to accurately measure your transmission temps from. That is your transmission cooler outline. I have seen temps get as high as 300 degrees coming out of that line. That line sees every 20 seconds 1 quart of oil pumped through it at 1100 rpms. 3. 8 gallons at 2100 rpms every minute, in 3 minutes you have pumped out basically 12 gallons of oil. So lets say you see temps of 300 degrees from this line and you have pumped it through your transmission At this point in time you can change the oil in your transmission or you can wait a little longer and change your transmission , rest assured you will be doing one or the other. I don’t make any extra money selling you guys the Chrysler lines, I give you the number we use, 5011244AA. The 1995 and earlier trucks it is a little more difficult to hook up the transmission temp gauge, but the 96 and later trucks you guys only have one choice, use the Chrysler line if you tow and want an accurate reading. To me, a gauge is there to monitor temps and indicate how often to change the oil. Since this is about a 3rd gen truck we purchase the line from one of our dealers Mass Diesel 1-508-660-7093, known as Scott to some of you as there is nothing from Chrysler and Scott did if first.

 

[Allnew2Me]

Thanks to all!

I had done a search for just this info but didn't really get a definitive answer, which is why I posted it here earlier today. I am ever impressed with the knowledge and also the willingness to share such knowledge that you all certainly have. It seems that the best place is not in the pan itself, which from my reading is where most people place it. That is why I asked and will do some research on the info you all shared. Thank you for all your answers in such a short time.

 

[R-N-R]

I used a Trans Temp Manifold from Jannetty Racing but I had a hard time installing it and wound up removing the line to get it installed without leaking. The product is fine, but my install was not With S&H, I think it cost approx. $50 and excess time. Mass Diesel has the replacement line with port advertised on their web site for $80. Although I have not used the replacement line, that is what I recommend.



Good luck to ya,

Bill

 

[DLBurns]

I had done a search for just this info but didn't really get a definitive answer, which is why I posted it here earlier today. I am ever impressed with the knowledge and also the willingness to share such knowledge that you all certainly have. It seems that the best place is not in the pan itself, which from my reading is where most people place it. That is why I asked and will do some research on the info you all shared. Thank you for all your answers in such a short time.

Hey David,

I couldn't make the meeting last night but you are welcome to come over and take a look at mine if you like! I have the 95 cooler line with the port.

Dave

 

[cyborg]

Mass Diesel has the replacement line with port advertised on their web site for $80. Although I have not used the replacement line, that is what I recommend.

Good luck to ya,

Bill

Does that line have twin ports to replace the factory line that has the sensor in it? or does it add a port somewhere else?

 

[R-N-R]

cyborg,

Can you explain, my factory line did not have a sensor port. I think the replacement line has one port for the temp probe.

 

[BrandonWoods]

how about the aftermarket transmission pans with the built in temp. ports??? How accurate are those?

 

[cyborg]

Now I'm going to have to climb under and have a look-see.

I would swear there is a factory port on the line.

 

[BPINE]

I like your user name there Dave.

 

[R-N-R]

how about the aftermarket transmission pans with the built in temp. ports??? How accurate are those?

Definitely better than nothing

But not as accurate as probing the hot fluid line. The fluid has an opportunity to cool in the pan, especially an aftermarket model with additional capacity.



Sorry, I don't know enough to guess at the temp differences, perhaps somebody more knowledgable than I will chime in with their $0. 02

 

[rweis]

I have a 47RE. Temp sensors in both pan and hot line.



Stop and go traffic no load T/C NOT locked up maybe 25* - 50*



Stop and go traffic with load T/C NOT locked up as much as 75*



Locked up about 10* - 15*.



I have an aux transmission cooler I run whenever I have a load. It helps significantly to keep the pan cool at about 150* and therfore feed the transmission at least cool fluid.



The worst is in reverse with a load. There is no airflow over the air cooler and the differences will go to 75* in about 30 seconds. I run the aux cooler (with fan) whenever I reverse with a load and then still sometimes I have to stop and let things cool down. I have a personal limit of 200* in the hot line then stop and let it all cool down. Generally happens when reverse my 5er pushing back in sand uphill.



Bob Weis

 

[Allnew2Me]

Again thanks to all of you for the suggestions. Hey Buff I do want to check out your trans line and also the other things you've done to your truck that are on my list. I did order the two wheel low kit from Bob and have all my gauges installed in my pod and cubby, so far. Hey Blair, my name reflects my standing here among you experts and I am certain that I will have it for some time, but I'm learning. Thanks to you also of course for all your help so far.

 

[Allnew2Me]

My latest solution

I have found a solution to my first post regarding the location of the transmission temp sender. I took many of the suggestions offered here and came up with a solution that so far seems to work very well.

Using a small block of aluminum about 5/8" thick and about 1 1/2" by 1", I drilled a 1/2" hole all the way through the 1" direction and then cut the block to it's final size of 1" by 1". This left the edge of the block with half of the drilled hole, which when placed against the 1/2" transmission line, fit the radius perfectly. Then I drilled a 5/16" hole in the center of the 5/8" dimension at ninety degrees to the 1/2" hole, all the way through to where the trans line would fit. I redrilled and tapped about 3/8" into this hole to accept my Autometer 1/8" NPT temp sender and installed it so that its end would just touch the line when the block was installed. I drilled 2 small holes that would allow me to wire it to the line and installed it, using heatsink grease to conduct the heat better. I placed it right on the trans line where it leaves the transmission, on the hot line out to the cooler. My first couple of test drives show that the temp comes up with engine temp and stays around 140 on flat driving in rather cool 60's weather. When I apply the brakes and give it the fuel, it raises in about 15 seconds to around 150 or so and then comes back down pretty quickly when I drive again. It seems to register the heat changes well. I will tow something up a hill this weekend to see how it reacts under load and hills, but it seems to be working fine.