Trans oil cooler and bypass questions for van

[nelstomlinson]

Transmission temps on my ambulance hit 200F coming back toward Fairbanks. I'm thinking of replacing the current, small external oil cooler with a TruCool Max LPD4739, with a thermal bypass. Anyone have any recent experience with the TruCool coolers or their thermal bypass?

 

[DirtyWood]

Do you run through the radiator too or just the external?

 

[nelstomlinson]

Definitely through the radiator, too! In winter the trans needs all the heat I can give it.

 

[IDIBOBS]

I wouldn’t even worry about the 200deg. Normal is 175-200.

 

[Nero]

I agree with idibobs, varnish starts forming at 220°f, so as long as you're below that, send it.

 

[nelstomlinson]

We have some long, hard climbs here, Thompson Pass is 2,600 feet in about 15 miles, for example. I'd like to be able to roar up out of there on a hot day with no worries.

 

[IDIBRONCO]

An ambulance is a heavy vehicle. You sure could go with a larger external cooler. In the winter time, you could cover all or part of it if you think that the transmission is being cooled too much.

 

[nelstomlinson]

Gross weight is just shy of 12,000 pounds, and I figure it'll never be way below that.

 

[Jim993]

200 F is a good fluid operating temperature. If you are worried about fluid oxidation, you shouldn't be at that temperature. I do think that we should all be using full synthetic ATF which is much more resistant to oxidation than petroleum based fluids.

Coming across the desert from CA to northern AZ a few years back, 110 degrees out at Needles, some long grades got my '85 F 250's (C6) ATF to 230 or so. Still going strong at 272,000 miles. I use Red Line D4 full synthetic in both my F 250 and my Corvette track car

You must be registered for see images attach

4L60 E auto trans). For many racing years with my Corvette I aimed at 250 F max for transmission fluid temperature, but once inadvertently hit 270. Red Line D4.

For a while I ran an LPD 4739 (40,000 GVW rated) on my Corvette but found that it restricted air flow through the radiator so that transmission fluid temperature on track did not exceed 205, -- but engine coolant hit 230.

Today I run a Hayden 689, 30,000 GVW rated cooler on the Corvette which is just right.

 

[Cant Write]

^this, you running full synthetic? If so I wouldn’t worry about 200F. If not, change the fluid.

Personally I’d still put a bigger cooler on though.