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I'm getting ready to put a bigger aluminum radiator in my 57 truck. My question is- I have a large trans cooler on it now that is not routed through the radiator. What are the pros and cons of running through the radiator + a trans cooler mounted in front of the radiator? I think the cooler I have been running has been fine, but the radiator on it now did not have an internal cooler for the trans either. What are your thoughts?



You left out an important piece of information - what kind of torque converter? what's the stall speed? How much HP? Engine size? What transmission? What rearend?

First, the oil to water heat exchanger you find in a radiator does several things. The heat from the transmission can help warm up the engine a little bit faster, and the heat from the coolant can help warm up the transmission faster. In other words, it links them a little bit. That's great if you use the vehicle often, or you live in a cooler climate/do winter driving

If you're running a stock-ish, low stall converter, and you're not using the vehicle constantly, you probably don't need an aux cooler at all if you start using the radiator cooler. As was mentioned above, many factory cop cars have the exchanger and an aux air cooler - but that's because of the severe duty and added heat generation. Are you using your vehicle that way?

If you're running moderate power or more, or a higher stall speed, you might want to keep the aux cooler in the loop to deal with that. The fluid can get very hot, and a single trip through the exchanger may not be able to deal with it.

The problem with an aux cooler in a low performance/low duty environment is not using a thermostat. You can get a thermostat for an aux cooler - and this bypasses the cooler entirely when it senses the fluid temp is below optimal. I would suggest a thermostat in all cases for the aux cooler. You wouldn't run your engine on the street without a thermostat, since it keeps the engine out of the ideal temp zone - and that increases wear and reduces oil performance.

On my car, I'd go to the radiator, out, to the thermostatic aux cooler, and then to the trans return line. That should give you the best of all worlds

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