Finally got around to changing out the two solenoids, hot side tube for the gauge install as well as the filter. I was fortunate enough to have a friend come by and help me remove the remaining old fluid in the transmission system. I credit the forum member that suggested a 5/8" clear hose attached to the return line at the transmission. Only suggestion I have to others is to have a drain pan below the hose connection.

I am sold on removing as much of the old fluid as possible, if you are not, try it for yourself. My friend thought I was nuts until he saw the color of the old fluid that came out at 3 quarts a time, 3 to 4 times total. The fluid smelled sweet, almost like coolant - color was a dark red / maroon. Some say that leaving the old fluid in is good, if that statement is correct, I question why they do not do that from the factory .

Regarding max trans temps, can someone give me an idea what is good temps and what is the limit that I should be concerned about? I would love to add another cooler but do not see where / how this can be done.
Thanks for the suggestion on the fluild removal.

Since I had an extra set of hands, we flushed the brake line fluid, which he thought I was nuts for doing this as well until the color of the old fluid came out. Amazing how easy it is to sell someone by seeing it first hand.

I am thinking of flushing the ps system next, i am assuming just remove a cooler line

 

Is the return the line closest to the front or rear? Also did you just leave it in N and add fluid as the old pumped out?

 

I am almost 100% positive it is closest to the rear, make that 100% now that I thought about it. I took another members suggestion and used a 5/8" ID clear tubing that I purchased at Fleet and Farm over the return line fitting. I then ran this into an empty windshield washer fluid jug / container. I ran it in neutraul as well as shifted thru the gears. I was fortunate to have another person with me; one to watch the jug and the other to start, stop, and shift the gears. We always stopped at about 3 quarts in the jug, filled the tranny with 4 to 5 quarts. If the fluid flow ever stopped, I simply yelled to shut off.
I had the truck on the lift but only enough to have the tires barely off the ground. I hope this helps.

 

I am by no means an expert on this subject but have read and experienced a few things in the past 30yrs of Rving that I believe to be valid. I welcome any comment on anything I may be wrong about!

The guage mounted in the hot side line coming off the transmission will give you instanteous temperature readings of the fluid so do not worry about the spikes you will see from time to time. My truck is an 05 with the 48RE and I believe your 04.5 will have the 48RE also. Anytime the torque converter is not hooked up you will see temperatures rise quickly. Mine will sometimes go to 210 degrees in stop and go up hill traffic. If you kick it into neutral the pump will still cycle the fluid and it will cool while waiting to move. The temperature while driving will show a more constant reading. They say it will be 80 degrees over the ambient outside temperature and I have seen this to be a fairly good estimate. My truck and probably yours also has two coolers, one water cooled near the firewall and another in front of the radiator cooled by air. I cannot see any need for another cooler. My temperature while towing a 9000lb 5th wheel is usually around 180/190 degrees or less depending on ambient. Steep grades at slow speeds will cause a rise. Sometimes while backing up or positioning in a campground it will spike to 220 if I take too long. This very quickly comes back down when I stop and let it idle in neutral. In Park it does not pump fluid so the transmission sits there heated up.

I have read and believe it to be true that if the Tow/Haul button is "on", the torque converter will stay locked if you are pulling a hard grade and the shift selector is in 2nd and the speed is above 30mph. This will save you lots of degrees on the guage. Always remember anytime the torque converter is locked it runs cooler. I have pulled many steep Interstate grades in West Virginia at speeds near 55/65 and never witnessed any rise in tranmission temperature....of course the torque converter is locked at that speed. It is when you drop below 25mph that temperatures rise.

Temperature spikes of a short duration are not a problem. The amount of time fluid is above 225+ will decrease it's life expectancy. There are charts on this somewhere on the Internet that show how long fluid can last at certain continuous temperatures.

Here is an important technique that I have learned over the years of pulling in the mountains. NEVER STOP if at all possible on the upside of a pull. Don't pull over at that overlook or attraction at the very top to "let it cool down." Keep it moving until you see good readings.....something below 210...then make your stop. Also never pull in and shut it down. This allows the heat to build up even more!! Let it idle in Neutral for a while so fluid will pump and cool down. Also the turbo needs to cool and spool down before shutting down it's oil supply.

 

I follow your suggestions already since I now have an EGT and trans temp gauage.

Regarding the locked in 2nd above 30mph, that seems to be the mystery question. I do not believe my truck will lock in second gear with the tow haul and with the shift indicator in 2nd. I will try in on the way home. I understand my gauge reads hot side but after a couple of minutes, the output temp and pan temp are going to be close, the fluid fully recirculates in about 2 minutes thru the coolers.

 

Since your TH is an OD lockout try it both ways. The newer trucks work differently with the TTVA motor and different trans control programs.

If your output and trans temp ar eclose after a couple minutes you have problems. The coolers will take 40-60 degrees out of the fluid so even if your only routing 50% percent thru the coole rin fluid coupling it should keep pan temps around 30 degrees less than then an avergae hot line, more if you are loaded.

In lockup they should generally stay within 10-15 degrees of each other, pan and hot line. The cooler return should be down around 130 or less depending on ambient and load.

 

I agree 100% that when locked, the trans temp is a linear relationship to the ambient outside temperature. I see my temps rise quickly is when I am pulling onto the freeway / driving around town with a 15K lbs behind me. When I get on the freeway, the torque convertor will not lock until into final drive w/ the th button depressed. I will try the 2nd gear and th button depressed. I will be installing that switch when I get home. I think it would have helped alot thru the mountains as well as one on ramp that was an incline thereby making a bad situation even more worse.