Transmission Temperature

[Matt400]

Hrmm, only thing I can think of at the moment is if your ECM has a different "flash" than my 03 did when I was working on that circuit.

More resistance will be needed to bring the temp gauge down to 220 degrees.

 

[MMeier]

More resistance means higher ohm on the resistor, correct? I'll go out after dinner and try one of the 220 ohm resistors i first picked up this morning and see what happens.

 

[nps]

If you put 2 220s in series you will get a 440 ohm resistor. If you take 2 180s and wire them in series you will get a 360. Keep trying till you get the right temp on the gauge.

 

[MMeier]

Guess the first 180 resistor I tried must've been bad. Went out after dinner and tried the 220 and all I got was a shade on the low side of 200, so I grabbed another 180, since the minimum I could buy was a pack of 5, and it came out to about 220 like you said Matt. So, far it seems to be doing what you said it should, able to keep my A/C kicked in all the time, and as long as I have the factory switch on, it seems to keep the low side pressure around 35-40. I will borrow a buddys set of gauges this coming weekend to check the high side also... . what should that be showing in 105-110* heat? Lost some freon when the blowoff valve went off, but was just blowing 25* out of the dash, just like it used too! Off topic... Neal, why isn't the boy on this site??

 

[MMeier]

Matt!!

. . while in override, the fan clutch should be engaged all the time, correct? No cycling bad and forth? Let me guess, time for another fan clutch... only 22k miles on this one, why can't D/C give us decent stuff!!!!???#@$%! If I bring RPMS up to 3500 then it kicks in for a few seconds then disengages, doesn't matter if the MFO is off or on, or the A/C is off or on.

 

[Matt400]

Well... sounds like you are using it for a different purpose than I was.

My intent was only to use it while slow going in reverse, especially backing a trailer to keep plenty of air going over the trans cooler.



It does sound like you have a bad clutch though.

 

[MMeier]

Main reason I wanted this was to be able to keep the A/C going like when I'm out loading up the trailer or taking cars off, that way I can cool my sweaty you know what off when I get back in. And to prevent the thing from heating up, it would get a bit warm when i pull my 40' around and then take into account it is up around 110* here lately, it doesn't cool off all that great. So, the fan should be engaged whenever it is in overrride, correct, regardless of other considerations?

 

[Matt400]

If all this is for the A/C, I have to ask. . if you have had the A/C TSB done?

My 03 didn't cool well at all especially at idle and I noticed the fan clutch was not engaging when I knew the condenser needed the air flow.



The TSB flash listed for this condition fixed mine. I used the MFO so little I never did the mod to my 05.

 

[MMeier]

Mine is not a California emissions vehicle, so this one would not apply, correct? If you been watching my other posts, I just put another fan clutch in the "thing" this afternoon, seems fine and dandy on the 20 mile test drive I took in 105* heat. Kept MFO in normal also. Would really like to know what the deal is with these fan clutches though, me and GShail can't be the only ones having problems with them. This last one only lasted 7 months and 22k miles.

 

[mtnram]

well I couldn't stand it

The engineer in me got me thinking of a better way.

Made of 6* aluminum axle shims, drilled, shaped and tapped. With hardware and sensor it's about 4 oz. I can lighten it up some more by cutting off the ends closer to the allen head cap screws.

Aluminum is an excellent transmitter of heat and it's not open to cooling as Geno's accu temp.

The 1/8" npt channel is bored through to the 1/2" dia. channel that will effectively clamp the trans line without crushing it. I'll put blue sensor safe rtv around the two "ends" of the 1/2" bore and fill the middle and sensor cavity with heat sink grease. If it's the least bit loose a minor sanding of the upper (sensor side) of the non-sensor half will allow a light clamping (and good heat transfer) of the trans hot side.

Took me about 3 hours to fab on the neighbors pos drill press which time included a run to the hardware store for a "q" drill (who keeps one of these on-hand?) and a #10 x 24 nc tap, mine was mia.

 

[mtnram]

Installed the above today in conjunction with install of hughes performance deep pan and band adjust.

After tightening and filling the truck idles for 7-8 minutes and the gauge (autometer c2) didn't budge, then took her to the quarter wash to clean the diff housings for lube change tomorrow.

The temp climbed to 140* and later went up to 160* driving up a slight grade and ultimately up a 1/2 mile 14% grade. The gauge reacted quickly to the temp change climbing the grade.

I think it works great.

 

[mtnram]

Update, just returned from an extended towing road trip, through ca, az, nm, tx to la amd returning through nv. The gauge reacts quickly and in what I feel is an appropriate manner. Temps maintained ~160-170* in traffic stop and go ~200-220* and finally up a 7 to 12 % winding steep hill hit ~220*, quickly returned to normal after reaching the top and continuing downhill.

I think I'll change the fluid to get the balance of the old stuff out. Nothing like a good workout to get the crud out of the corners.

 

[BHanna]

Nice work mthram. Your temps sound like they're right about what I see with a sensor plumbed into the hot line. You should go into business.

 

[Yo Hoot]

But surprisingly enough, they are also fairly easy to heat up while running with-out a load. Running stock coolers, temps over 250 (line) are far more common then most would imagine, while towing. It only takes about 3 miles of stop and go traffic on a 85-90 degree day to obtain.

I copy that. Round town on the hilly backroads she hits 220 easily, no load.

 

[TCDiesel]

I agree with Ya, I pull 20/30k weekly here in MN in stop-an-go traffic,but this can be easily overcome with the Fan override switch, with the added benefit of cooling the A/C condenser. Yo Hoot your setup is awesome, but it's subject to road conditions, In MN the chloride that the HWY dept sprays on the road will the destroy the electric fan Motor in short order.

 

[Yo Hoot]

I'm really glade you posted your findings, many think they are safe with regard to transmission temperatures when in fact they are indeed at risk. The most accurate readings are those taken from the transmission cooler lines as it exits the transmission on it's way to the coolers (yes their are two). This is the area that will tell you what temperature the transmission is seeing. I have been researching transmission cooling temperatures, and the effects of additional cooling for almost two years in an effort to combat the problems associated with high load/high power use. The sender in the pan only shows the fluid temps after cooling, which is only half the picture, and very miss leading. Transmission fluid has a set life cycle, at 190 degrees with everything being normal, it should last for 75,000 miles. Unfortunately, transmission fluid is severely affected by temperature spikes, and most all users will not or should not allow so much time to pass before replacement. Transmission fluid has it's useful life cycle reduced by 1/2 for every 10 degrees the fluid goes over 190. That means if the fluid goes to 200 even once, the life cycle is shortened to 37,500 miles. Let it rise to 210 and it goes to 18,700, even worse let it get to 220 and that now drops to 9,375 miles. The problem most have, is they monitor the fluid temps after they have been cooled, which is sort of back wards. I have experimented with 2qt and 4qt transmission pans, extra coolers both front mounted and else ware, synthetic fluid and conventional. Fluid temperatures for our transmissions are very easy to manipulate, they as expected run their coolest at highway speeds, with the TC locked. Under these conditions, temperatures of 140-150 (pan) and 170-180 (line) are very common and very acceptable while both towing and hauling large loads. The problems start as we decrees the speed, city traffic, rush hour conditions, or anything that has us stopping and starting without longer periods of sustained speed. As expected, you will build temperature faster while towing or hauling heavy loads, but most seem to think they are OK while running empty, which is not the case. I did alot of testing with a 16,000Lb trailer, and as you would imagine temperatures are pretty easy to heat up with such a load. But surprisingly enough, they are also fairly easy to heat up while running with-out a load. Running stock coolers, temps over 250 (line) are far more common then most would imagine, while towing. It only takes about 3 miles of stop and go traffic on a 85-90 degree day to obtain. The absolute worst condition for high transmission temps are backing, here because of the design very high temperatures occur in a very short time span.
The use of over sized transmission pans is not a cure, they do hold more fluid which acts as a buffer between the extremes, but they do nothing to cool the fluid. Yes the fined aluminum pans look good and are an improvement over stock, but they did no better then the stock, thin steel pan. If anything they hurt, by giving the user a false sense of security. We need to understand that we expect an awe full lot out of our 40+ year old automotive automatic transmission. Looking on the insides (yes I took it apart) damage from heat is not only apparent, but the major component to failure. I found that heat was generated the most from the TC and the overdrive unit in normal conditions. The good news is with a few minor changes to the cooling system itself, and some driver education the heat can be controlled and or minimized. Frankly, I am amazed that this old slush box performs as well as it does, considering it's ancient design, the fact that it is a gasser trany put behind a diesel and rated to tow as much as it does, and how small most of the inside parts are.

I see those temps . . brand new trans... second one. Around town no load it will sometimes get to 240. I can't image what might happen if I were a landscaper pulling a stumpgrinder around these hilly backroads never getting into overdrive.
What few minor changes to the cooling system?

Also, the fluid coming out of that cooler line is the hottest and was just brought up to that temp by the TC and has left the trans. Doesn't that mean the trans internals don't see that heat? It goes directly from being heated by the TC then out of the trans and in my case back to the Derale fan cooler, and up front to the front cooler and finally back into the trans. By that time it should be down a good 30-40 degrees I'm guessing if not more. Maybe another inline sensor at the return line just before goning back into the trans would give a good read on how well the cooling works. I also think they came up with the ATF+4 specifically to better live in higher heat environments. I think this trans simply generates heat beyond the abilities of the fluids. Now I see why some will not use an automatic for heavy pulling all the time.

I'm currently using a Dipricol trans temp gauge which I have been unhappy with. It's seems to be very sensitive to electrical interference. One time it spiked to full temp and never came off. I pulled over wiggled the connection at the sensor and pushed the wire around under the truck, restarted the truck and it went back to normal. After having another trans installed it was acting up again... just giving strange readings. I pulled the wire off the sensor and applied electrica l grease. That seems to have fixed it.

 

[TCDiesel]

I have 3 temp sensor In My 03 ,the internal factory on the IQ,1 in the pan and 1 in the front servo, they all read differently,0-40*, I am guessing that the TC temp has to reach 400* at times (Monetarily) In Hot summer and pulling mix that in with stop-an-go traffic without the fan-override I can easily hit 270* on the IQ,230* on the servo,220 on the Pan. If I did not live and travel in extreme cold I would install the system Hoot has. maybe even 2 Plate and fin coolers. 1 with fan the other W/O. Also I would probably remove the heat exchanger and keep the auxiliary cooler up front. I miss Y-knots postings ,does anyone know what happen to him?

 

[alexanderJ]

I've been following this and other similar threads closely. Last week while pulling my 5th wheel up a steep hill I hit 250 degrees in the transmission out to cooler line (sensor installed in the Mass Diesel adapter).



I pulled over a couple of times to let it cool down. From reading the posts maybe I didn't really fry my transmission.



So, what to do now? Change out the fluid with only 6K miles on it? Try a deep pan and add a second temp probe for future monitoring? Would Amsoil ATF provide an advantage? I feel Matt's fan overide switch would definitely be an improvement if I can find the right value for the resistor in a '05 CTD.



Any advice right now would really be welcome.

 

[TCDiesel]

Matt400 I think may know the value, What I do is start a 180ohms with my scan tool and + or - until 215* after 219* the CEL will come on, I cannot remember the value on 05 and higher. I really like the additional ramp to 1000 Rpms. Also we have electronics lift's that I use my 03 to raise, Turn fan override on, plug into lift hit the switch and truck ramps to 1k Rpm. Matt400 thanks again.



You didn't harm anything at only 250*

 

[Yo Hoot]

So basically the 240 deg rule for the newer synthetic fluids is pretty much outdated? What might be the breakdown temp for synthetic trans fluid?