Anyone heard of running cooler lines through cooler only, instead of from tranny to cooler to radiator to tranny? Cooler is stock unit on a 97' Z71(too small maybe). TCI recommended this.

You can run lines to just about anything that you want. The theory of going through the radiator first, is to lower the oil temperature more effectively by cooling it in stages, vice just going to a small cooler. The radiator will carry away heat in step one, then the cooler will take the temperature down further. This allows for a cooler return line temp, than just using one cooler or the other. What was the original question to TCI, for them to recommend the small external cooler ONLY?

I go only into an aftermarket high capacity tranny cooler on my '89 suburban. The advantage of this is that if the engine overheats or gets really hot, you're warming up your tranny also... and can cook it.

The downside of this is that in cold weather, you don't have the engine warming up the tranny fluid. However, in HOuston this is not really a big issue. You may want to repost in the engine/drivetrain section...

:agree:
If you live in a sometimes cold climate, you're gonna want that rad cooler in series with your aftermarket.
However, if you've puked a tranny, you definately DON'T want to reuse the cooler in the rad cuz of all the nooks & crannies in it. Aftermarket ones are usually smooth tubes inside and can be flushed.
Cheapest/Biggest tranny cooler I ever saw was an AC condenser with the connections snipped & plumbed to the trans.

A friend of mine at a trans shop built a transmission for a durango, and the guy brought it back a few months later, because the trans went out again. When they took the trans out, it was full of antifreeze and water. Thats the only advantage of running it through the trans cooler only.