Hemi Towing coolant and transmission Temperatures?

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socalluke
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Hemi Towing coolant and transmission Temperatures?

Post by socalluke » Wed Jun 17, 2020 11:48 am

After smoking my overdrive clutches in the 2012 transmission a year ago, for a number of reasons. Pulling a 7-9k lb toyhauler with WDH.

Currently 1) Now have tuner, with tires changed to correct size of 35inch tires. 2) Shift kit in trans with firmer shifts and hunts less and 3) will limit to 4th and down or 3rd and down based on grade and lastly 4) drive up mountain grades based on engine rpm, Not trying to maintain a certain speed.

Just got back from a 900 mile tow. LA - Chandler - Flagstaff - LA. (4th gear, 2800 rpm, and 62 mph. Kept the coolant and trans temps the coolest.)

But on the 2nd climb in a row, (meaning the neither trans or coolant had a chance to cool back down) the trans temp got up to 230)
Coolant would get up around 221 a fair amount throughout the trip. Once when the coolant hit 225, I turned off the A/C and the coolant temp dropped almost 10 degrees super fast.

With CA and AZ heat over 100 degrees and mountain grades pushing the limits, At what Temperature would you pull over and let it cool off?
1. Coolant Temp?
2. Trans Temp?
3. And other than as cool as possible, at what temperatures would you consider it is okay to run at?

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PWJouster
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Re: Hemi Towing coolant and transmission Temperatures?

Post by PWJouster » Wed Jun 17, 2020 11:55 am

since you modified your trans, you may as well throw additional cooling capacity in there. Another radiator would do alot for you.
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Colibri
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Re: Hemi Towing coolant and transmission Temperatures?

Post by Colibri » Mon Jul 27, 2020 12:53 am

Coolant temp is okay from around 195/205 up to around 230 or sounder heavy load, that’s pretty normal. Also consider that your oil temperatures can be 10-20 degrees higher than coolant especially under load.

ATF+4 is pretty decent stuff, it’ll handle high temps better than some fluids, but ideally I wouldn’t let it hit 230 with any regularity. 170-190 is ideal

Check your trans fluid condition and consider a drain/ refill.

Buna and nitrile start to shit the bed over 250, those materials account for a fair number of seals and o rings in a drivetrain. Something to keep in mind
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socalluke
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Re: Hemi Towing coolant and transmission Temperatures?

Post by socalluke » Sat Aug 01, 2020 12:33 pm

Thanks @colibri. Exactly what I was looking for

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