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Discussion Starter · #1 ·
Here is what is happening. We just bought a 33' foot bumper hitch camper that weighs 7K. While pulling it home, my engine was running slightly above 200 degrees and my Trans temp light came on. The temp outside was 100.

I had all the fluid replaced in the transmission.

1. Was going to order a deep Aluminum pan, but after reading about a dozen posts saying the pan did nothing to cool the tranny.

2. I need to check the fan clutch to make sure its working correctly. This could be the culprit.
3. Checked the fins of the intercooler, trans cooler, ac condenser, radiator. All are good.
4. Thinking about buying an aftermarket trans cooler with a fan. Do you just bypass the factory one or use both? Install in in front of intercooler?

I have spent about 2 hours searching the forum. I plan on searching more tomorrow.

Truck i think is all stock. 2003 CC SB 5.9HO 555 48RE
 

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Well make sure the fluid level is all good. A cooler with a fan on it helps alot. I put one on my truck alittle while back and it helps keep it nice and cool. I bypassed the stock cooler all together made my own lines and works great. Flex a lite makes a good one that the one a I have.
 

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I am no trans expert but your trouble lies from your torque converter not locking up while you are towing. I creates a lot of friction because it is basicly letting your trans slip. Wiring up a lock up switch and using it once up to speed everything will cool down. The bad news is when you see the trans temp light there is a good chance you cooked some discs or your torque converter. If you notice it slipping under normal driving one of those would be the culprit. If not you were lucky and you can get away with added a couple of things to help out. If you tow a lot I would look into a valve body and triple disc to go along with the lock up switch. Your stock cooler will work fine you just need to get the converter to lock up.
 

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Discussion Starter · #4 · (Edited)
Mjensen. I'm planning on upgrading to a triple disk and valve body by the end of summer. I'm going to put a trans temp guage to see what's going on.

dieselfanatic87: where to did mount the trans cooler? Orginal spot or in front of intercooler?
 

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also consider an addon torque converter manual lockup switch to use while towing.
really never should tow heavy or high wind resistance loads with the stock converter in 3rd and 4th unlocked for more than a few seconds due to the excessive amounts of heat produced in the TC due to the inefficient viscous coupling torque converter section. the OEM converter is not built to handle the massive torque of a Cummins diesel, it's basically a low torque rated gasoline engine TC.
 

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It sounds from your first post that the fan clutch has gone south. This could effect all your temp problems. My coolant temp normal is 195 even towing and it is now running at 200 empty. A/C gets warm at idle at a stop. Of course my tranny is manual so no temp problems there.

I suspected the fan clutch and had Dodge check the electrical to make sure that the clutch was the actuall problem. They quoted me $58 before the test, but cost me $39.95 when done.

I will be replacing the clutch in the morning. Don't want an over heating problem as I will be towing the 5'er next month on a long trip.
 

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Discussion Starter · #7 · (Edited)
Ok, The Fan Clutch tested good. Now, I guess it time to look at the Torque converter. My Truck has 155,000 on the clock. The tranny seems to shift and act fine (except the last time towing.) I'm wanting to replace the Torque Converter. I called a guy and got a quote. His response was my tranny is wore and I need a total rebuild (all over the phone, Guy didn't even drive or look at truck). I'm no tranny expert, but disagree. We have the shop and equipment to replace torque converter. I'm thinking might as well see what happens and just replace it myself.
 

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I pulled a 53 ft car carrier with three cars behind my truck to the race track saw temps on my trans temp gauge peg my gauge which is located in the hot line coming out of the transmission. But no light came on in the dash. My fan clutch works. I can verify. My guess would be you cooked your transmission does it slip? I would suggest a rebuild and a nice converter and valve body. I think next time if I do tow that load again I will put a manual TQ lockup switch in my truck. But what makes it worse is that my truck and your truck is also running like a 35" tire which is a lot of weight to sling around so that doesn't help much. BTW with my calculations the trailer weighted close to 18k..
 

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When you did the fluids in the trany did you adjust the bands, I have a DD maghytech trany pan, it holds around 24 quarts and it does drop my trany temp around 10 to 20 deg depending on the outside tamps. Do you tow also in tow haul mode.
 

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Discussion Starter · #10 ·
No, The Transmission Doesn't slip. I pulled the trailer afterwards 70 Miles with no trouble. Its my daily Driver and shifts and acts fine.
 

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Discussion Starter · #11 ·
Yes I use the tow and haul, but when I'm up to speed and on fairly level ground I would turn it off.

I just printed the How to adjust the bands. Will look into doing that as well.
 

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On 03's and 04's Tow Haul is just an overdrive switch..
 

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The tow/haul on '05-up is just a TC lock up switch past 2nd gear right.......?
Cause thats what mine does, and I love it; bein able to lock the converter at 30 MPH every so often is nice.
 

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Yes I use the tow and haul, but when I'm up to speed and on fairly level ground I would turn it off.
That could be the reason for your problem, not the way the TH should be used.

A new TC won't cure the problem if your just spending too much time in fluid coupling, or, you have a circulation problem in the cooler. The factory setup is more than adequate if it is functioning correctly.

What conditions caused the temp light to come on? Slow and go traffic? Steep grade? Speed? Did you have OD locked out and was the TC locking?
 

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Discussion Starter · #15 ·
The temp light came on on flat or little grade. I was doing 60 to 65 in overdrive. We were just cruising along when it happened. We had been for about an hour or two when it happened. I assume the TC was locked up. I don't have the mystery switch.

THe Tow Haul Switch just takes it out of OD Correct?
 

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Discussion Starter · #16 ·
SO Im trying to figure out what my next step. Should Upgrade the TC to be safe? Then an a Mystery switch? I guess part of the problem was towing in OD was not the best thing to do. Sometimes we have to learn stuff the hard way.
 

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At 50+ you should be locked up and not building heat from fluid. There is the off chance your drums were slipping a bit which can be corrected with the band adjustment but i doubt it.

I just pulled a 12k 5th wheel yesterday in 100+ temps and as long as she was locked temps stayed well below 150 on the gauge. So im wondering if your factory trans temp sensor is a bit screwy, atleast during your last pull.
 

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Before you go and spend a gigantic wad of money on a TC and Vb grab your repair manual and see what your sensor is rated at in ohms, and check that sucker with a voltmeter. A 7k trailer is WELL within factory tow limits.
 

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SO Im trying to figure out what my next step. Should Upgrade the TC to be safe?
You need a gauge first to validate you actually are having issues or it is an electrical glitch. Anything else now is just guessing. Add a trans temp gauge in the cooler output line and start monitoring it. Do NOT trust the data port outputs as they can be flaky also.

Towing in OD is no problem at those speeds and weights. You do need to validate the TC is locking and stays locked though. I tow all the time even at 23k gross in OD with no heat issues.
 

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The temp light came on on flat or little grade. I was doing 60 to 65 in overdrive. We were just cruising along when it happened. We had been for about an hour or two when it happened. I assume the TC was locked up. I don't have the mystery switch.

THe Tow Haul Switch just takes it out of OD Correct?
You'll know the TC is locked when you give it a decent amount of gas and it sounds like a mack truck.... also the rpm's will rise alot slower, and the engine sounds 100% different.....IMO
 
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