I am asking those that tow with a class A gas and have a transmission temperature gauge. What temp does your gauge show while you are towing? I am set up to tow my Jeep GC behind my 2001 Workhorse chassis with a 4l80e transmission. I have a scan gauge programed to monitor the trans temp but I have yet to tow with it installed. It has just been to cold here to try it out.Thanks,Ed

olfarmer, Well Sir, it's not the same rig or, even transmission but, it may give you some form of reference. Ours is an '04 Itasca Horizon 36GD with the C-7, 330HP CAT engine and Allison 3000MH trans. During normal, flat ground, no-strain towing, in temps that hover around say, 65-86 degrees, that trans will sit at about 125-140 degrees, plus or minus a few. But, if I start climbing a grade and, the outside temps start to rise to, oh, around say, 95 degrees, that trans temp will shoot to about 175-200, plus or minus. That rig never moves an inch without towing. We're presently towing a 5300 lb. 2011 GMC Sierra Extended Cab 4x4. And, sometimes it's got a 300 lb. lift/carrier in the back which, is carrying a 900 lb., GL 1800 Honda Goldwing. So, that's what kind of load(s) is on ours and how it reacts in various towing situations. Scott

Thanks Scott,Quite a difference in rigs and you are towing a heavy load but it gives me some information.Ed

My current '94 Foretravel w/Allison is pretty much right on with scotts. But then my old '94 Allegro 454 TBI with the Chevy transmission was also close to that too. Could get it up to 150 once in a while. I actually wondered if it was working when I firsst hooked it up. And I was towing a Ford Focus. Depends lots on where your sensor is located. In general auto trannys don't run hot.

99 Ford V10 38 foot under 90 degree is around 125 and over 100 where it is most of the summer here is at 150. I only tow so can not give you any other readings.

You need to answer another question-- where are you measuring trans fluid temperature?I have seen senders on line out to cooler, on return line and on some transmissions, on the transmission itself.Reading will/should vary by location.

What is your transmission temperature | Good Sam Community

34 Replies

olfarmer
Explorer II
Jan 10, 2014
More To See, Thanks for that info. That seems like it would be a good place for a sensor as it should tell the actual temp of the transmission internal parts and not just the oil.
Ed
More_To_See
Explorer
Jan 10, 2014
olfarmer wrote:
Does anyone know where the sender for the computer is located? I assume that most later model chassis with a transmission temp gauge would read from the computer where after market add on gauges might be located in any of the mentioned locations.

My GM service manual shows that sensor as being buried inside the tranny on some kind of a harness. This might be worth a bit of investigating with an experienced tranny rebuilder for some more info about that sensor.
Airstreamer67
Explorer
Jan 10, 2014
It seems to me the transmission pan is the best place for the sender.

If the sender is on the transmission line coming out of the torque converter, it will show the "spikes" which result from when the converter is unlocked during acceleration or in lower gears climbing mountains, but these are usually temporary spikes and have less effect on the life of the transmission.

If there is a problem with the transmission, the pan temperature will probably indicate it the best IMHO.

I have probes on both the transmission lines and the pan. As I said, when the transmission is unlocked, the line temps go up but the pan temperature doesn't unless the transmission remains unlocked for a long period. When the torque converter is locked on the highway, ie the longer-term state, the temps just about equalize.
olfarmer
Explorer II
Jan 10, 2014
I agree with BigRabbitMan, The location of the sender will greatly affect the temp reading on the gauge. Does anyone know where the sender for the computer is located? I assume that most later model chassis with a transmission temp gauge would read from the computer where after market add on gauges might be located in any of the mentioned locations.
WinnieToGo
Explorer
Jan 10, 2014
The highest I have seen is 165 on my scan gauge with an Allison 5 speed and ambient temperature of 80 degrees. This is going up the Cascades in Washington at about 55 mph. This seems low compared to some of the bigger rigs. I am at 18.5K lbs fully loaded with no toad. I have no idea where my sender is.

-Scott
BigRabbitMan
Explorer
Jan 10, 2014
Brian in Michigan wrote:
One of the issues is where will you put the sending unit? Will it go on the output side of the transmission or do you put it in the pan? Mine is on the output of the transmission so I can monitor the heat coming off of the torque converter. I guess in a perfect world, you would have 2 sending units one in the pan and one on the output of the trans.

This is the issue that makes many of the transmission temp comparisons/evaluations/reports meaningless or not comparative. There are four places where transmission temp senders are placed. In the pan, in the test port, in the line going to the external cooler and, lastly, in the line coming from the external cooler. There are valid reasons for placing the sender in each of those locations.

So unless you KNOW the location of your sender, temps reported are meaningless. If you put a sender in each of those locations, you will get four different/divergent temps at the same time. So if you are going to report a temp, also report the sender location and then we can all learn something.
BrianinMichigan
Explorer
Jan 09, 2014
One of the issues is where will you put the sending unit? Will it go on the output side of the transmission or do you put it in the pan? Mine is on the output of the transmission so I can monitor the heat coming off of the torque converter. I guess in a perfect world, you would have 2 sending units one in the pan and one on the output of the trans.
Mr_Mark1
Explorer
Jan 09, 2014
On our coach (listed below), our normal temps driving down the road are 195 for the engine and 199 for the 6 speed Allison. The most I've seen either go up to is about 215-217 climbing the pass from CA to NV (to/from Las Vegas).

When we arrive at a campground and I let it idle while checking in, it will fall to about 178 (engine) after 15 min. of idle.

MM.
ThorResidencyNe
Explorer
Jan 09, 2014
My tranny gauge is an Autometer, so hopefully it's accurate. I've thought of adding a larger capacity transmission pan along with synthetic fluid and a larger cooler (the factory one is small). As for the fluid, I changed it when I bought the motorhome and I've only put about 1k miles on it in a about a year. The fluid still looks bright red and does not smell burnt at all. I also added the Banks Transcommander to firm up the shifts and help the tranny.

As for weight, it's a pretty loaded RV with 2 slides, tag axle, tile floors etc.It rides great and runs good since I added the Banks Power pack to the engine. Thanks.
olfarmer
Explorer II
Jan 09, 2014
I don't know but 210 to 215 on normal roads sounds a little too hot to me. If it is actually running that hot I would consider a larger external cooler, especially if you are going to tow. You might ask a mechanic whether those temps are too hot. I would at least change the fluid fairly often as I believe the fluid breaks down faster at high temps. Does the fluid have a smell or look brown? It should be bright red and not smell burned. You have a pretty heavy rig for a gas motorhome.