Trans Temp Gauge

[datkinsonsr]

I installed an Auto Meter calibrated trans temp gauge with the sensor in the front plug port on the drivers side of the transmission. I also have an aux trans cooler rated for 15000#. The fluid level is indicating full. Driving around town with an unloaded lawn trailer the trans temp was above 250F. My gauge tops out at 250F. 90 degrees + outside right now. What temps should I be expecting city/highway driving with and without the trailer? Thanks in advance.

 

[Hydro-idi]

IMO, there may be a couple things happening here. You may be experiencing inaccurate gauge readings or you are having issues with your transmission (maybe torque converter slipping). Those temperatures are way too high for any automatic transmission. Truck unloaded, they should be between 130-180 degrees. Truck loaded, they will be a little higher but they shouldn't ever get to 250 degrees. With temps like that, you will burn up that transmission in no time.

 

[datkinsonsr]

Thanks for the reply. My transmission was o'hld and upgraded with a billet torq converter and other upgrades not too long ago. I have also heard that where you place the sensor in the trans can give you different readings.

 

[Hydro-idi]

I could be wrong here, but I don't think there would be a 100 degree difference from one location to another in regards to where you locate your transmission sensor. I would put a temp gun on the transmission oil pan and see what that temperature is. Then you will know if your gauge is reading correctly or not. Then we can go from there.

 

[PwrSmoke]

Another possibility: I believe that port reads the converter oil temp, which is always the hottest oil in the trans because it's often slipping.. until the converter clutch locks in, which it does only intermittently in town. Try going out on the highway and let the converter lock up for a long period. If it goes down 50-60 degrees, that's it. Pan temp would be a lot lower (the 50-60 degrees). 250F converter temp around town around town on a hot day with some load is within the normal realm. What kills ATF is TIME-at-Temperature, so short spurts at 250 aren't immediately dangerous but those periods of high heat chisel away at fluid life. A percentage of the converter oil goes out to that big cooler and returns for lube flow.

 

[datkinsonsr]

I just used a scan gun at the sensor and showed 150F. (Harbor freight scanner.) If I can confirm this with a second scanner, I guess I know what my problem is.

 

[Hydro-idi]

150 degrees is much better. That is a normal transmission temperature.

 

[PwrSmoke]

I've had temp senders in three places on older trucks and could read the temp of the pan, the cooler out (the hot time out to the trans cooler) and the cooler in(from the trans cooler to the trans) line. I had one gauge mounted but a three way rotating switch. When the pan was 140, the cooler out (remember that's converter oil) was 220 while cooler in line was about 150 or so. I can read two temps on my '05 F150 right now and while cruising down the freeway, converter locked, pan temp and cooler out are about even. Soon as I am in town, shifting up and down a lot and not locking the converter much, cooler out temp is always 50-80 degrees higher. You can get used to "normal" reading converter oil temp once you understand what "normal" is... but if your gauge only goes to 250 and you are pegged there all the time, it's not telling you much useful. That's why I like a sensor in the pan, even though it's more work to install. If you see pan temp at 250, you know you are in a heap-o-trouble and cooler out is likely in the 300F range. Finally, the transmission with lockup converters are usually a little more "loose" than a non-lockup. This is to enhance acceleration and torque multiplication and when they are unlocked, they usually generate a lot more heat than a non-lockup converter.

FYI, the pan temp in my '86 (C6) seldom gets past 140 even on the hotest days Even when I used to tow at 18K GCWR, I hardly ever got to 180 let alone 200. Yes, it has a big cooler.

 

[trackspeeder]

I installed an Auto Meter calibrated trans temp gauge with the sensor in the front plug port on the drivers side of the transmission. I also have an aux trans cooler rated for 15000#. The fluid level is indicating full. Driving around town with an unloaded lawn trailer the trans temp was above 250F. My gauge tops out at 250F. 90 degrees + outside right now. What temps should I be expecting city/highway driving with and without the trailer? Thanks in advance.

You might have a bad gauge or sender.

Rule of thumb for tranny temps 100 degrees over air temp.

 

[gandalf]

I'd go with either a bad gauge or a bad sender. If you've recently had the trans overhauled, and assuming they did a good job, you should never see 250°F.

I have the sender in the port on the driver's side (Isspro sender and gauge), and have a large trans cooler. I usually run anywhere 150°F--165°F. That's with a big 11 foot cabover camper in the bed acting like a big sail. It has the aerodynamics of a huge brick.

You must be registered for see images attach

This picture is half upside down. The seam is parallel with the ground, the sender is above the seam, and forward is at the bottom of the picture. Does everyone (anyone) understand that?

 

[datkinsonsr]

Confirmed the temps with a second temp gun and both are within 1 degree of each other at 164F after a 10mile drive with empty trailer. I installed the sensor as per instructions using Teflon tape. I wonder if there is a good ground being made? Will have to wait until tomorrow to check this out as it is POURING right now. Thanks for all the responses.

 

[Ruger_556]

Confirmed the temps with a second temp gun and both are within 1 degree of each other at 164F after a 10mile drive with empty trailer. I installed the sensor as per instructions using Teflon tape. I wonder if there is a good ground being made? Will have to wait until tomorrow to check this out as it is POURING right now. Thanks for all the responses.

Get rid of the teflon tape and use a good quality pipe sealant... Just run a thin bead around the top threads so that it can ground through the lower threads. I put my sensor in the pressure line to the cooler. Used a T-fitting and ran a ground wire to the frame rail. Also make sure you used the right gauge wire.

 

[datkinsonsr]

Will be removing the Teflon tape today. I used 18ga as recommended by Auto Meter.

 

[Wicked97]

If your sensor is measuring converter output temp its not out of line.
Ideally you want to measure what's coming out of your coolers though.

 

[PwrSmoke]

^ This.

As I said earlier, I THINK that port shows cooler outflow, which comes from the converter and it's the hottest oil in the trans and having monitored that aspect on four truck over 25 years, I can say that 250 isn't out of line. If that port isn't converter oil, then nevermind but I'd be curious to know what circuit it's tapped into. I don't have a lube flow chart for the E40D.