how hot is too hot for trans temp

[hex0rz]

Had to pull the 5th wheel today. Been a couple years since I've done it. Blew my intake boot twice, too.

Had to back it into a tight spot and take things slow. Had it in 4low even. Can't remember, how hot is too hot for the trans temp.?

[Wild and Free]

Depends on the oil standard or syn, 230+- tops for regular oil and if it was there for an extended period I would dump it, syn can go up higher but if I saw 250+ I would dump syn oil as soon as I could too even though it can handle higher temps for a lot longer it would be cheap insurance. Realistic it could handle closer to 300 but I would not feel good about running it if it hit those temps.

 

This is if it was measured at the converter outlet cooler line at the tranny, if one saw those temps in the pan your tranny is Kentucky fried already.

[Mopar1973Man]

If I'm not mistaken the temp sensor is near governor sensor so it's in the pan and trans temp light cones at 290 or so.

[hex0rz]

I have an isspro installed per instructions. I believe the sensor is installed on the line coming out of the transmission going to the cooler.

Sounds like I'll need to be dumping the fluid soon.

[Wild and Free]

How hot did it get?

[Mopar1973Man]

FSM...

 

 

Trans Over-Temp Lamp-On Message - Each
time the cluster receives a trans over-temp lamp-on
message from the PCM indicating that the transmis-
sion fluid temperature is 135° C (275° F) or higher,
the indicator will be illuminated and a single chime
tone is sounded. The lamp remains illuminated until
the cluster receives a trans over-temp lamp-off mes-
sage from the PCM, or until the ignition switch is
turned to the Off position, whichever occurs first.
The chime tone feature will only repeat during the
same ignition cycle if the transmission over-tempera-
ture indicator is cycled off and then on again by the
appropriate trans over-temp messages from the PCM.

[hex0rz]

When backing in, it was hovering around 220. It still seems to shift good and strong. I'll check the fluid and see if it's discolored or burnt smelling.

I can't say I haven't exceeded 230 before pulling a utility trailer up in the mountains going up in 1st gear. Still on the same fluid so I guess I was okay.

I cannot believe dodge would set the temp so high knowing that's too much heat already. They should have it set at like 200 or something. Before you get in the danger zone...

[Wild and Free]

Your fine, no worries at that point where you are measuring.

[hex0rz]

That's good to know. I checked the fluid and it doesn't smell burnt. But I've always seemed to have trouble understanding what burnt fluid smelt like. It always smells terrible from the get go to me lol.

My compressor side intake boot must not have been on properly for some time now. Back up to making 35 pro boost and definitely have a big difference in driving now. Before the boot was fixed I was only hitting 25 pro at best. Talk about being a dummy. Can't believe I didn't see it sooner.

[Ilikeoldfords]

Seems like that tranny temp dummy light is like the low oil pressure light. Once the light comes on, the damage is probably already been done IMHO.

[Wild and Free]

Pretty much!

[joecool911]

The age old debate...get constant temperature fluctuations with sensor coming out of the hot side line or monitor fluid in the pan. Do short term temperature spikes really hurt the transmission? Or is it most important to know when the cooling system cannot keep up with the demand of a long and hard pull? Seems as if we're providing cooled fluid to the transmission that it would be happy. What would worry me most is knowing that we are in a cycle that cannot be sustained. Thoughts?

Easiest/cheapest way to tap into the hot line is what?

[Buzzinhalfdozen]

I guess the best set up would be to put a temp sensor in-line and in the pan. When I install one it will probably be on the pan, I guess I'm more interested in overall system temp. Look at pretty much any hydraulic system (essentially all a trans is) and the temp gauge is on the reservoir.

[IBMobile]

Easiest/cheapest way to tap into the hot line is what?

 

Put temp sender here   

 

1. install sender unit into T fitting.

2. cut pipe. I used a small tube cutter.

3. take the pipe off the heat exchanger and cut off about 3/8" from it. use a hack saw for that.

4. slide compression fittings on both pipes.

5. install T fitting with sender unit on to the pipes and hand tighten the fittings.

6. reinstall pipe on to heat exchanger.

7. orientate the sender unit.    

8. be sure the pipes are pushed in to the T fitting, then tighten the compression fittings.

[joecool911]

Is that connection near the transmission or radiator?

[IBMobile]

That's the pipe that comes out of the trans and go to the heat exchanger under the exhaust manifold by #6 cylinder so you'll see the temp coming out of the trans not the cooler temp of the trans cooler that would dump into the pan. If you grill a steak and burn it, take it off the grill, let it cool down and serve it, IT'S still burnt steak. The same thing with trans fluid. If you cook the fluid, cool it and dump it back into the pan, IT'S still burnt fluid. You just don't know how burnt it is.       

[Wild and Free]

That's the pipe that comes out of the trans and go to the heat exchanger under the exhaust manifold by #6 cylinder so you'll see the temp coming out of the trans not the cooler temp of the trans cooler that would dump into the pan. If you grill a steak and burn it, take it off the grill, let it cool down and serve it, IT'S still burnt steak. The same thing with trans fluid. If you cook the fluid, cool it and dump it back into the pan, IT'S still burnt fluid. You just don't know how burnt it is.       

 

I got a good chuckle out of the description but it is about as good of one as can be put to laymans terms.

 

The heat doesn't damage the tranny so much as it breaks down the oil which is what protects the tranny system, lessen the protection ability and then you shorten the life of everything inside the trans. Heat can cause the seals to harden over time depending on how high it was then it could harden them earlier and cause internal leaks which also creates its own set of issues all resulting in shortened tranny life.

 

By monitoring the oil at its hottest point helps with knowing if the condition of the oil has been compromised and for how long, it also is an indicator of converter issues and or a slipping lockup clutch, if the temps climb at that point while in lockup you have slippage occurring and you would never know that by measuring in the sump.

 

I ran 2 tranny temp gauges at the same time on my 02 one in the hot line leaving the converter and one I moved between the pan and the servo port which was always the coldest temps and never varied at all.

 

The Cooler line at converter output by tranny was consistently 30-35* hotter than sump temps during normal operations and daily driving and could get to 40-50* hotter during town driving and towing heavy, it was not uncommon to see the same tranny temp as engine temps during these conditions hovering 180-200*.