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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[toyota_mdt_tech]

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.

Yes, and look at the area between AC condensor and the radiator, there is a void between them that gets debris built up you may not ever see unless you remove top shroud. Anything in there blocks air flow for tranny cooler, AC condenser and radiator. Make sure fan coupler is locking up. Rev engine up a little when this elevated temps appear, can you hear your cooling fan really pulling air? It should, vs not being locked.

Is your engine temps stable where they are supposed to be? If so, this means the tranny is generating this heat. When a torque converter "sears" or cuts the oil, this drives temps up. If you are in lots of stop and go, where you may not be seeing stall speed at the converter reached, then it goes into second gear because of the small load (light throttle) and then engine slows down and back under stall speed.

The same scenario happens traveling at slow speeds in dry fluffy sand or deep snow. Never reaches torque stall speed. Best bet is to manually pull your trans down into a lower gear, ie 1st to not allow it to shift up and if you are going faster for 1st, then pull it into second. Main thing is you want engine RPM's to meet or exceet stall speed. Also, pop it into neutral and elevate engine RPM's too to help cool things down, other option is to add a supplemental trans cooler to your existing ones. Please dont wire tie it to the radiator, especially if its aluminum, will damage the core and eventually leak coolant.

A downside to manual low is it does automatically increase line pressure which can raise temps (reverse does the same, keep this in mind if you are even pulling someone out of a rough spot, use manual low vs Drive low.

OK, a little ATM-101. Hope it helps.

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[monkeh]

She's in the shop now; the UK is in a heatwave, so leaving at 4 am to make a 220-mile journey on known roads for stop-start traffic got me there.

Once it was +50mph, I locked up and just kept cruising.

Trans temp never rose over 165.

As the sun came up and hit roadworks 100 miles in, trans temp rose to 175ish.

Once I arrived at the town, the stop-start immediately began spiking.

Long and short, they arrived unscathed.

Verdict, clutch pack on 3rd gear was toasted, warping the steel liners.

About a month wait for spares, the rebuilder is having issues with obtaining spares.

I'm in no rush for it.

He's adding an aux cooler to the setup, removing the thermostatic valve.

The fan clutch does work.

When diagnosing the overheating, I used a hose on the cooler to drop the temperature, and water pooled in the fan shroud.

When the engine temp was reached, it called for the clutch to be engaged, and a massive spray of water shot out from under the hood.

Whatever pooled on the radiator, i/c, the condenser was ejected up all over the place.

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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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[toyota_mdt_tech]

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

Bingo, the biggest culprit is debris collecting between radiator and condenser or inter-cooler.

Check the voids between units; they get lots of debris in there.

Also, the fan coupler should make lots of noise, pulling lots of air at slower speeds.

You can hear the difference.

Also, make sure foam packing around the shroud is all in place, or airflow can be diverted around the radiator; you want it to all go through it.

Fan shroud fit well, packing in place, all pieces there?

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[monkeh]

Well, she's back. Jeez, I'm glad.
Rebuilt, with a 7? Clutch setup, new flex plate, TC and "performance rated up to 900bhp and 1000+lbs/ft of torques"
Heat, on the way home wasn't an issue, it touched 200 in the city I left in stop start traffic, but I think it may have been pot luck. But the 8 hour drive home in stop start traffic, she topped at 190. With a/c off and fan clutch not operating, it hit coolant temp at 195 max.
Once I've recovered from the £5k rebuild cost, a mishimoto kit is being installed.

Fan clutch is being suspect. Ones ordered from rockauto. It's having its oil done next week. When the clutch arrives.

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[Corkey]

Well, she's back. Jeez, I'm glad.
Rebuilt, with a 7? Clutch setup, new flex plate, TC and "performance rated up to 900bhp and 1000+lbs/ft of torques"
Heat, on the way home wasn't an issue, it touched 200 in the city I left in stop start traffic, but I think it may have been pot luck. But the 8 hour drive home in stop start traffic, she topped at 190. With a/c off and fan clutch not operating, it hit coolant temp at 195 max.
Once I've recovered from the £5k rebuild cost, a mishimoto kit is being installed.

Fan clutch is being suspect. Ones ordered from rockauto. It's having its oil done next week. When the clutch arrives.

Glad you're fixed back up, man.

Please give me a review of the intercooler.

Edit- did you get a billet input shaft in your build?

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[monkeh]

Sorry, I missed this.

Yes, the Billet shaft was one of the things I had to wait a while for.

Something admirable that I never will see.

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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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