96Bounder30E
America is my home!
Moderator
Joined: 11/21/2002
View Profile
Good Sam RV Club Member
 Offline
|
cruising7388 wrote:IMO, the pan is the worst choice for a single measurement. There are two temps you want to quantify:
1. How hot the fluid is coming out of the transmission.
This measurement determines the maximum temp to which the fluid is subjected and indeed is precisely the temp point to which the longevity tables should be applied.
2. How hot is the fluid when it returns to the transmission. The differential between this temp and the output temp determines the
efficiency of the cooling portion of the circuit.
I have my temp sender located in the pan.....I also have a thermostatically controlled Derale fan mounted Tranny cooler up front......the fan turns on at 180F........my gauge also reads 180F when the fan turns on...and when the fan turns off the reading on the gauge is slightly below 180F.....therefore I don't believe there is a huge differential between pan temps and output temps......
|
mike4947
N. Syracuse, NY
Moderator
Joined: 08/26/2002
View Profile
Good Sam RV Club Member
Offline
|
We ahve done about 6 multi sensor mounting tests over the years. some with two inputs, one from the pan and one from the output line. Two with three inputs, one from the pan, one from the outlet and one in the return line.
NEVER was the output sensor at the level of a pan sensor. That's why you have a cooler.
Under heavy loads such as towing near the GCWR of the rig, or steep inclines the sensor all reacted the same. The output temp would raise first, then we'd see a rise in the input line and WELL AFTER the temp rises in either of those two the pan sensor would start to rise.
YEs, it is possible to "fry" transmission fluid (temps above 260 degrees F) without the pan temperature even climbing. The better the cooler setup the less likely high internal temps (fluid output temp) will show on a pan sensor.
It takes a lot of thermal energy to raise the large amount of fluid in the pan any amount. And the cooler setup also keeps the pan fluid at a more constant temp, but we've fried fluid quite a few times without a pan sensor registering temps anywhere near the low limit for fluid degradation of 260 degrees.
blog.rv.net Your daily guide to the Open Road
Subscribe to the daily digest
They say you learn by your mistakes, in that case I must be a genius.
|
cruising7388
Nevada
Senior Member
Joined: 06/29/2005
View Profile
Offline
|
96Bounder30E wrote:azrider61 wrote:The pan temp is about the coolest place for the tranny fluid. If you have a very efficient cooler you'll never know how hot your tranny is really running with the sender in the test port at the pan. Hope this helps.
I wonder why Mag-Hytec puts sender ports in their pans if this is the wrong place to locate it?
They stuff the sender port in the pan because it is faster, cheaper and more convenient. That hardly makes it right.
|
cruising7388
Nevada
Senior Member
Joined: 06/29/2005
View Profile
Offline
|
mike4947 wrote:We ahve done about 6 multi sensor mounting tests over the years. some with two inputs, one from the pan and one from the output line. Two with three inputs, one from the pan, one from the outlet and one in the return line.
NEVER was the output sensor at the level of a pan sensor. That's why you have a cooler.
Under heavy loads such as towing near the GCWR of the rig, or steep inclines the sensor all reacted the same. The output temp would raise first, then we'd see a rise in the input line and WELL AFTER the temp rises in either of those two the pan sensor would start to rise.
YEs, it is possible to "fry" transmission fluid (temps above 260 degrees F) without the pan temperature even climbing. The better the cooler setup the less likely high internal temps (fluid output temp) will show on a pan sensor.
It takes a lot of thermal energy to raise the large amount of fluid in the pan any amount. And the cooler setup also keeps the pan fluid at a more constant temp, but we've fried fluid quite a few times without a pan sensor registering temps anywhere near the low limit for fluid degradation of 260 degrees.
THANK YOU! It's a pure pleasure to read a post from someone who really has investigated this in spades. While the rest of us have been talking the talk, you've been walking the walk.
|
cruising7388
Nevada
Senior Member
Joined: 06/29/2005
View Profile
Offline
|
96Bounder30E wrote:cruising7388 wrote:IMO, the pan is the worst choice for a single measurement. There are two temps you want to quantify:
1. How hot the fluid is coming out of the transmission.
This measurement determines the maximum temp to which the fluid is subjected and indeed is precisely the temp point to which the longevity tables should be applied.
2. How hot is the fluid when it returns to the transmission. The differential between this temp and the output temp determines the
efficiency of the cooling portion of the circuit.
I have my temp sender located in the pan.....I also have a thermostatically controlled Derale fan mounted Tranny cooler up front......the fan turns on at 180F........my gauge also reads 180F when the fan turns on...and when the fan turns off the reading on the gauge is slightly below 180F.....therefore I don't believe there is a huge differential between pan temps and output temps......
Hmm, this just does not compute. You might conclude that the pan temperature was close to the INPUT temperature but you don't have the slightest idea of what the output fluid temperature is.
|
|
|
96Bounder30E
America is my home!
Moderator
Joined: 11/21/2002
View Profile
Good Sam RV Club Member
Offline
|
cruising7388 wrote:Hmm, this just does not compute. You might conclude that the pan temperature was close to the INPUT temperature but you don't have the slightest idea of what the output fluid temperature is.
coming right out of the tranny......your right!......I don't know........but, I do know the fluid has to be 180F to turn on the fan mounted on the Derale cooler.........and when the fan does come on the pan is also at 180F.........they coincide perfectly........so what ever?
I do know one thing for sure.........my fan never comes on either at highway speeds or even crawling up a hill........it only comes on when I get off of a freeway or highway for about 4-5 minutes.........
I am confident my transmission cooling system works quite well!.......I attribute alot of this to the removal of the trans cooling circuit from the radiator.......I use all external transmission coolers......
|
azrider61
Scottsdale, AZ
New Member
Joined: 08/20/2004
View Profile
Offline
|
not to be an arse but all you really know is that the fan comes on at 180, not the actual temp of the fluid. 300 degree fluid will make it come on also. Like I said before, if you have a very efficient cooling setup you'll never know what temp the fluid really was before it was cooled down. The other unknown is where is the temp sensor in the tranny cooler.....input side or output side.
|
96Bounder30E
America is my home!
Moderator
Joined: 11/21/2002
View Profile
Good Sam RV Club Member
Offline
|
azrider61 wrote:The other unknown is where is the temp sensor in the tranny cooler.....input side or output side.
In my install the temp sensor is located on the inlet side of the cooler with fan attached........
The followiung is copied and pasted from this site.......www.turbodieselregister.com
Transmission Temperature Gauge Install -- The installation for the transmission temperature gauge was made easier by the presence of my Mag-Hytec transmission pan, since the aluminum pan had a 1/8" npt port on the drivers side. I've heard a lot of debate about the best place to put the sensing element for reading transmission temperature on an automatic transmission. Some like to put it tin the pan, others state that it should be in the line going to the cooler to read the highest possible temperature in the transmission. Some members have reported that their's is installed in the cooler outlet line and in talking to a Camping World installer, he stated that this is where they install them. I think that more important than the installation point, is the ability that the gauge gives to monitor trends and to notice a significant momentary or sustained change in the temperature. I was planning to install it in the cooler inlet, but I have found that having it in the pan provides a pretty rapid response to changing conditions. I personally do not agree with the cooler outlet installation.
Overall, I have to agree with his assesment......
For Shorts and giggles I think I will put an additonal sender unit in the output line going to my Trans coolers.......
|
bill h
coastal reconquista
Senior Member
Joined: 08/02/2001
View Profile
|
96Bounder30E wrote: .....I think that more important than the installation point, is the ability that the gauge gives to monitor trends and to notice a significant momentary or sustained change in the temperature.
Yup.
Converter outlet should give the first indication of heat increase. Another reason I like converter out temp is it gives you not only info to save your tranny, but it also tells you how much heat your are putting into your radiator, thereby allowing you to perhaps avoid an engine overheat by shutting off dash air or whatever else you do. I like your idea of doing both locations. That allows you to be sure you don't exceed max pan temp. GM says it is 285F for the TH400. Get back to us on that, huh?
NOTE: Any incorrect spelling is intentional to prevent those annoying popups.
84 Barth 30Tag powered by HT502/Thorley/Weiand etc, Gear Vendors OD.
Siamese Calvin and Airedale Hobbes, 4WD Toyota toad
|
moe f
ON.
Senior Member
Joined: 08/25/2002
View Profile
Offline
|
To solve the dilemma of where to place the sensor for the transmission temperature unit I installed two complete units. One as the fluid comes out of the torque converter, and the second as it leave the coolers ( have added a larger cooler in addition to the original).
The truck has expired from warranty, so next time I do a transmission fluid change I will add a drain plug to the pan and install the second temperature sensor in the pan.
When towing I get a differential of 15 to 20 F between the two gauges. When not towing the differential is negligible.
cheers
|
|
|
