48RE Trans Getting Hot!

[monkeh]

Thanks for whitelisting the UK; I'm glad to be back!

I've got a slight issue, and Smarty reports higher than average transmission temperatures.

I did a bunch of city driving on my commute to work (about 8 miles), and my Smarty began the pre-panic of saying my trans temp was 210°f.

Locked up, got on the motorway at 60mph, and dropped to 195.

Back into town, I'm up in the 220°f with the Smarty wailing at me.

I'm running a 5-9 12v tune and recently serviced transmission - sucked out 3 liters, replaced, then drove, dumped another 5 liters, then replaced the filter and used synthetic atf+4.

We can't get Mopar atf+4 in the UK, so I had a UK synthetic ATF +4.

We're in the middle of a heat wave with temps up in the 30s (dunno what that is in Fahrenheit).

Stop-start traffic without availability to lock up the clutch.

Flir shows temps are true around the trans cooler, and I'll upload those tomorrow.

So I don't suspect the t'stat playing up.

Is 220 fine for unladen stop-start City driving?

I try and drive in "2" to lock up as much as possible, but with 20 mph being introduced in residential areas, it's difficult to get speed to save-temps.

And the UK government is doing this for emissions!

I can't see myself driving around in 4L!

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[timshooter40]

I would not want to sustain that temp for long.

I would be looking to see if your trans cooler is blocked or needs cleaning; maybe put an electric fan on the trans cooler also.

You could run a coolant exchanger to keep temps down in traffic.

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[watersupply189]

30C = 86F, which is flipping still too hot for me.

Try washing out the cooler to make sure it’s not plugged up with debris and junk.


2016 Ram Laramie 3500, G56, 6.7, CC, 4x4

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[Corkey]

I would try to hook a good scanner to it and see if there may be a deeper problem that may be the issue.

Does the trans slip at all?

I would start with the cooler being plugged like what's mentioned above.

Doing the recent fluid change could have dislodged debris that is stuck in the cooler or line.

Do the 48's have a thermostatic bypass?

I'm not very savvy yet on 5.9's.

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[monkeh]

A quick check today, from what I can feel, hot fluid goes in, hots coming out, my dad pinched my flip phone, so I can't check specifics.

I put the truck in gear, parking brake on, let the temps creep up to 200°f, got the hose out, and began wetting the trans cooler.

Temps took about 4-5 mins to drop down to engine coolant temps.

Also found out the electric clutch works when it is engaged, pulling water into the fan and soaking me!

I'll check the trans cooler for blockages; I hear "thermostatic valve" mentioned, so I might also try that.

The trans isn't slipping; it locks up fine.

Would compressed air be enough to check for blockages?

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[timshooter40]

I'm not sure about using compressed air.

I have pulled and used reverse flush to find blockages.

Pretty simple flush from one port watch flow, then reverse port flush; if flow looks the same, you are good.

Look for debris.

REMEMBER, DON'T USE WATER!

Use trans fluid only; water and transmission don't work.

Just a little water in transmission, bad things happen.

I hope this helps.

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[monkeh]

Well, I removed the cooler.

I will take it to work tomorrow, and solvent flush it.

I want to adress the thermostatic valve.

Plus, if theres no rubber bits in the cooler, I can soak them in the solvent.

You say no water!

Damn that ruled out a 6-bar steam flush!

I noticed that the check valve is leaking slightly.

I might focus on thats deletion as well.

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[monkeh]

As promised - FLIR imagery.

Weird readings, though.

Smarty is showing 185, but trans cooler lines are showing 161° in, and 143° out

After a short idle in drive, parking brake on- smarty reports back a temp of 185, FLIR of the pan is showing 151°f?

flir_20220719T165355.jpg

flir_20220719T165417.jpg

Weird.

Anyway, I will post updates post-clean.

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[watersupply189]

Maybe the Smarty is reading the temp wrong?


2016 Ram Laramie 3500, G56, 6.7, CC, 4x4

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[monkeh]

Initial flush, Black sludge came out, thats not a good sign.

I don't suspect a blockage, more like laydown.

Flushed it out with acetone; the thermostatic valve was a pig to get out; cleaned up fine and re-fitted.

I manned up, began sucking out the fluid through the dipstick and extracted about 5.5 litres of black fluid.

Not good, considering I only changed the fluid last year (Dump, refill, run, dump, replace filter).

I fear the transmission may be dying - I had a lot of black gunk on the magnet.

I will do another dump and refill within the week; I fear it may be another expensive replacement on the cards.

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