Transmission Temps How low is to Low

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Noel
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Joined: Tue Apr 10, 2012 11:09 pm

Transmission Temps How low is to Low

Post by Noel »

Hi
I have a 2107 Px2 4x4 and have been seeing trans temps over 100 Deg C when towing my van 3.5T a little too hot for regular use, so i installed the thermal bypass valve and external cooler, not towing trans temps are between 60 & 70 Deg C at highway speeds 100Kph in Melbourne, My Ranger is mainly used for towing.
Question is 60 to 70 Deg c too low for non towing use ? and can this damage the transmission.
catherder
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Location: Canberra, Oz

Re: Transmission Temps How low is to Low

Post by catherder »

IMHO...
No you won't hurt the tranny. Consequences you might experience are altered gear change behaviour and maybe a fuel economy increase. What are your temps when towing? If I was going to make changes to ATF cooling I would aim for an operating temp range of 80-90C.
From my reading Mercon LV is designed to operate at about 90C +/- 10C. (This doesn't mean the fluid doesn't oxidise at higher temps...)
Ian B
19 XLT 3.2 auto
Noel
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Re: Transmission Temps How low is to Low

Post by Noel »

Transmission seems great no changes in operation and fuel economy is sitting on 9.7 after a run from Werribee to Sale and return which I am happy with considering the mods on it. I haven't towed yet but was trying to be somewhere between 80 and 90C, I will post temps when I do a trip.
I have 2 x 15 row coolers with fans that operate at 80C via thermostat, they are mounted under the alloy tray at the rear of the ute, I can't see the sense of putting them in front of the radiator to add extra thermal load to the engine. I did have 1 x 15 row cooler and still saw temps around 100C when towing in 30C plus days that's why I added the extra cooler and the thermal bypass.
mjt57
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Re: Transmission Temps How low is to Low

Post by mjt57 »

Here's one opinion on ATF temps.

https://www.colvoss.com.au/blog/2019/12 ... mperatures

I suppose that you'd need to refer to the ATF supplier's datasheet and the specs on the fluid in question.
Grant L1
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Re: Transmission Temps How low is to Low

Post by Grant L1 »

I have had an aftermarket cooler and thermal bypass valve in my tranny since 2013 or 14. There has never been any alteration in the shifting over a wide range of ambient temperatures, minus 5C to 40+C.

When the box is flushed and the fluid changed there is no sign of wear in the filter or fluid.
Rosspat
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Location: Adelaide

Re: Transmission Temps How low is to Low

Post by Rosspat »

I have never seen a post anywhere on any forum saying "my trans failed because it ran too cool"
I have read plenty about too hot failures
2018 Winning Blue XLT
itsme
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Re: Transmission Temps How low is to Low

Post by itsme »

Yup never heard of any auto failures due to low temperatures; matter of fact never heard of any failures due to high temperatures. Bearings clutches bands converters etc but not temperature faults. :shock:
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