Saw my Trans Temp soar to 274* today!

[michaelrc51]

I have a 2009 Ram 1500 CC with 545rfe trans and we were on our way home from a 2.5 hour trip and I just happened to click through the dash gauges when I saw the trans temp at 260* and then climbed to 274* in the last 25 minutes of the trip. I wasn't towing anything and now that I have verified how ridiculous that temp is I am trying to figure out if my trans is on it's way out and how/ why the temps reached that high.

Truck is an 09 with 91k miles on it and a few mods. Stainless Works 1-3/4" headers and full 3" dual exhaust with X pipe and cats, Vararam intake, Moe's ported TB, V6 efan, 180* thermostat, and wheels with 35" tires.

Also, I did a complete trans service about 15k ago and added MagHytech deeper pan.
I replaced the radiator 3k miles ago as well as the trans cooler lines.
The fluid level is where it should be and the radiator/ cooler isn't clogged or very dirty.

I was shocked to see the temps but I never felt any slipping. I'm thinking at best case scenario I need to flush and replace the fluid now but I am thinking I might need to get the trans rebuilt.

After the truck cooled down, we drove the last 15 miles home and I watched the temps go from 100* to 175* in the 20 minutes that it took to drive home.

Any suggestions?

 

[TruckNut]

Wow that’s crazy. Was your fluid burnt smelling or was it discolored at all? If so then the temp gauge is probably right. If it isn’t then maybe things aren’t as bad as they seem. You already said the cooler looks ok........

 

[Fitz-0518]

My tech prepares our vehicles for summer each spring. One of the important things he does is clean out (high air pressure) all of the coolant fins in the radiator, trans cooler and AC condenser. I watched this last spring. I am guessing, but I believe I swept up a good 1/2 pound of bugs and dirt that came out of those parts. 03 5.7 coolant temp went down about 5 degrees.

 

[Joes1500]

First thing I would check is that efan, make sure it is doing what and when it is supposed to . Watch the trans and coolent temps.

Then I would pull the trans lines off at the trans if possible and blow through them with a air gun. Make sure the lines are not clogged. If they aren't, then you can hook up the pressure side and start the truck. Might have to put it in gear but fluid should spray out the other line. Then you know you have circulation.

If all that checks out and your still seeing high temps, I would put a mechanical gauge on it and compare temps.

At close to 280 I would think the fluid would be browning and starting to smell.

 

[huntergreen]

Drop your pan and see if the filter came off.been known to happen, but I have no idea if this will raise the temps.

 

[S0CAL]

My tech prepares our vehicles for summer each spring. One of the important things he does is clean out (high air pressure) all of the coolant fins in the radiator, trans cooler and AC condenser. I watched this last spring. I am guessing, but I believe I swept up a good 1/2 pound of bugs and dirt that came out of those parts. 03 5.7 coolant temp went down about 5 degrees.

Damn, that is a good idea right there.

 

[michaelrc51]

So, I checked the fluid and as I said before the level was fine. Also, the fluid didn’t look discolored and if it had any burnt odor I couldn’t smell it.

I watched engine and coolant temps once I saw an issue with the trans temp and neither were high. Since new rad, T-stat, water pump, and Efan mod I have not seen my coolant hit even 200*.

I’m hoping maybe this is just a sender issue but I don’t know, it seems to read the full range.


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[CLOUDL1GHT]

I have a 2009 Ram 1500 CC with 545rfe trans and we were on our way home from a 2.5 hour trip and I just happened to click through the dash gauges when I saw the trans temp at 260* and then climbed to 274* in the last 25 minutes of the trip. I wasn't towing anything and now that I have verified how ridiculous that temp is I am trying to figure out if my trans is on it's way out and how/ why the temps reached that high.

Truck is an 09 with 91k miles on it and a few mods. Stainless Works 1-3/4" headers and full 3" dual exhaust with X pipe and cats, Vararam intake, Moe's ported TB, V6 efan, 180* thermostat, and wheels with 35" tires.

Also, I did a complete trans service about 15k ago and added MagHytech deeper pan.
I replaced the radiator 3k miles ago as well as the trans cooler lines.
The fluid level is where it should be and the radiator/ cooler isn't clogged or very dirty.

I was shocked to see the temps but I never felt any slipping. I'm thinking at best case scenario I need to flush and replace the fluid now but I am thinking I might need to get the trans rebuilt.

After the truck cooled down, we drove the last 15 miles home and I watched the temps go from 100* to 175* in the 20 minutes that it took to drive home.

Any suggestions?

Not too long ago I had a friend who's torque converter was failing. Only sign of it though was high transmission temps.

It also was on a diesel.

 

[michaelrc51]

Here's a thought......The Cat is right under the trans pan, maybe the exhaust moved around and the Cat was laying against the transmission pan??

Still not sure that the outside of the high flow Cat would get hot enough to get the fluid temp that high, but it's a possible theory.

 

[indept]

Not too long ago I had a friend who's torque converter was failing. Only sign of it though was high transmission temps.

It also was on a diesel.

^^^^^ This
If the torque doesn't lock it will create a ton of heat.

 

[O.R.T.]

My tech prepares our vehicles for summer each spring. One of the important things he does is clean out (high air pressure) all of the coolant fins in the radiator, trans cooler and AC condenser. I watched this last spring. I am guessing, but I believe I swept up a good 1/2 pound of bugs and dirt that came out of those parts. 03 5.7 coolant temp went down about 5 degrees.

^Ditto, do that. I did it recently to a work truck and you'd be surprised how much the condenser and radiator hold onto that needs to be washed/sprayed off to clear the fins. If you have the tow cooler also clean that off.

 

[Roncrawford67]

Hate to say it but it is a Dodge transmission. I have a 96 that was replaced right after the warrenty ended. Again two years later and then again another 2 yrs after that. I had the tow package and owned since new and never towed anything.

 

[Cobalt]

You mentioned a Mag-Hytec transmission pan. It should have a drilled and tapped hole that is intended for a temperature sensor. I found that the B&M gauge is priced reasonable and performs quite well. I installed a Mag-Hytec pan on my 68RFE and found when towing, I will still get close to 200 degrees. I added a remote trans cooler and didn't see but a 10 degree drop and a slower rise in temperature. When I installed the B&M temperature gauge, I noticed a 30 degree difference in the temperature in the pan as to what was on the dash. There is a thermostat internal to the 68RFE. I tow a 12,500 lb 5th wheel and there are several 5-6 mile grades in my travels that are 6-7%. Normal temperature for around town and short Hwy trips empty is around 160 degrees.

 

[michaelrc51]

You mentioned a Mag-Hytec transmission pan. It should have a drilled and tapped hole that is intended for a temperature sensor. I found that the B&M gauge is priced reasonable and performs quite well. I installed a Mag-Hytec pan on my 68RFE and found when towing, I will still get close to 200 degrees. I added a remote trans cooler and didn't see but a 10 degree drop and a slower rise in temperature. When I installed the B&M temperature gauge, I noticed a 30 degree difference in the temperature in the pan as to what was on the dash. There is a thermostat internal to the 68RFE. I tow a 12,500 lb 5th wheel and there are several 5-6 mile grades in my travels that are 6-7%. Normal temperature for around town and short Hwy trips empty is around 160 degrees.

I’ll try that out. I’m gonna replace the sending unit as well, but I don’t think that’s the issue cause it seems to read the whole range.

I drove it 1 hour in each direction this weekend not towing anything and watched the temp go from under 104* to 213*. This was normal driving, mostly highway.
I have noticed that it seemed to stay more stable on back roads and around town as opposed to the highway.
I’m gonna get new filters and do a fluid change. This time I’ll try to pump all of the fluid out.


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[Burla]

Ester based fluid will buy you 30 degrees F as far as oil degradation goes. Mechanically something is f'd up and needs to be fixed. A ester based transmission fluid will run cooler and not break down under heat if higher temps is a new normal for the truck. No matter what you will have to get the temps to come down if the reading is accurate, but if after the fix you are still having hotter then normal temps, might consider running ester based oil. Fix the issue now, or you will be rebuilding very soon. Good luck

 

[Burla]

The 8 speeds run hotter then the 6 speeds and yet they have a "lifetime" fluid, when temps are hot that is when you need real synthetic oil not atf-4. 8 speeds run pao fluid, but ester/pao mixed are even better. Redline c+ for 6 speed, redline d6 for 8 speed, ester/pao based fluids. Nick at gotexhaust sells it as cheap as anyone.

 

[michaelrc51]

Ester based fluid will buy you 30 degrees F as far as oil degradation goes. Mechanically something is f'd up and needs to be fixed. A ester based transmission fluid will run cooler and not break down under heat if higher temps is a new normal for the truck. No matter what you will have to get the temps to come down if the reading is accurate, but if after the fix you are still having hotter then normal temps, might consider running ester based oil. Fix the issue now, or you will be rebuilding very soon. Good luck

Yeah, but the question is why is it getting so hot?
I’m not towing and it seems to be worse at highway speed, even coming down at stop and go speeds.

I find it really strange that the fluid doesn’t smell burnt and is still red in color, not brownish like I’d expect from those temps.
Maybe it is the sending unit, IDK.

This is an 545RFE trans.



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[Burla]

Since you have no other symptoms like slipping or shudder, maybe they damaged the valve body when they changed the pan or you need a new transmission solenoid. Why did you change the trans cooler lines?

 

[Burla]

How did the transmission shop do you fluid change? If they ran the torque converter dry, they could have ruined it. I find it fishy this happened soon after the transmission service.

 

[michaelrc51]

Since you have no other symptoms like slipping or shudder, maybe they damaged the valve body when they changed the pan or you need a new transmission solenoid. Why did you change the trans cooler lines?

I changed the pan myself, pretty sure it went on with out damaging anything.
I haven’t given the solenoid much thought.
I changed the cooler lines cause I did the heater core and Evap coil, radiator, water pump, etc.....
The lines were getting rusty and since I had to take out the radiator I figured I’d swap them out.
I like to stay ahead of maintenance items, especially when things get a little rusty.

If I don’t figure out what’s going on, I’ll build the trans.


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