I have a 2000 F-350 with the 7.3 and ZF6 manual trans. I've installed a temp probe into the trans case to monitor fluid temps. While towing the fluid temp will exceed 200°. Is this normal or should I consider installing an auxiliary cooler?

 

200°F is normal.

 

Hummm...thinking that the ZF6 has a pump and sends the fluid through the radiator, there is no reason you couldn't install an automatic transmission cooler???

 

200-250 degrees is nothing for a manual transmission, they don't have clutches inside them that burn up when they get too hot like automatics do.

 

Temp must be somewhat of an issue if there is a pump and cooler???

 

Chevrolet used the ZF6 behind the duramax, no pump or cooler. I have a friend with one, with over 400,000 miles on it, and he's rough on the truck. He's never touched the transmission. I suspect that the cooler on Ford's is only necessary in the most extreme circumstances.

 

I can't help on the temps, but my old truck was an 03 250 6.0 zf6. I was headed to Harlan KY on a 4 wheeling trip combined weight of around 18.5k with the trail rig on the trailer plus camping stuff. On Fancy Gap grade on i77 my top radiator tank blew apart. No one stocked a manual transmission radiator so I bought an auto radiator instead. The cooler fittings were the only difference. I used spare 3/8 fuel line to bypass my cooler and continue the trip. By the time we got to the campground about 4 hours later the transmission was scratching going into 3rd and 4th gears. There was a bit of mountain 2 lane driving involved. When we left 3 days later (with the truck cooled off) it shifted smooth the first couple of hours. After we got back down to the flat lands (I'm near Fayetteville NC) it was shifting smooth too.

I added an aftermarket cooler rather than replace the radiator again and never had another issue. I don't know if there's any difference inside a GM zf6 compared to Ford but towing pretty heavy in hills I'd make sure it's there.

 

"The model used in the Ford trucks has an internal oil pump to circulate and cool the lubricant, which is uncommon in manual transmissions. The GM versions are not equipped with an oil pump."

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