[Ron G]

Installing new lines and forget to identify the fluid routing. Please confirm if this is correct.

Top port on the TH400 is the outlet and connects to the bottom port on the radiator. The fluid is returned from the top port of the radiator and connects to the bottom port on the TH400.

Thanks in advance for your reply.

 

[TOMR67]

Why would you run top line to bottom of radiator? I had a th400 in mine and don't recall having the lines crossed

 

[Ron G]

Why would you run top line to bottom of radiator? I had a th400 in mine and don't recall having the lines crossed

So your saying the top line goes to the top port on radiator.

 

[Paisan]

The bottom line on the transmission is definitely the hot outlet side and the top fitting on the transmission is the return cold line. My radiator has both fittings on the bottom. I believe it is the same for both TH400 and TH350 trannys.
Good luck..

 

[TOMR67]

Its hard to describe what's in the radiator its basicly a double wall copper pipe that the trans fluid flows through, direction is irrelivant imo

Here is a pic

 

[Ron G]

I have done some additional research and will connect the bottom line (hot) from the tranny to the bottom port on the rad. The top port on the rad (cooled) will return to the top port on the tranny.

Thanks for the feedback Tom and Jeff.

 

[TOMR67]

That's also a good Pic showing why guys overheat, calcium

 

[KeyKeeper]

Never understood why anyone would want their transmission fluid (super hot) to go to another hot source... Ive always ran an external cooler.

 

[Ron G]

All right I am perplexed. Roughed in the pre bent lines that I bought and it's the opposite at the rad. Hot line from tranny connects at the bottom of the rad and the return line is at the top of the rad. Seems a little counter intuitive to cool the tranny fluid.

Found a pic and even though it is hard to see it appears that this is the way the lines were installed when I pulled the engine.

Never understood why anyone would want their transmission fluid (super hot) to go to another hot source... Ive always ran an external cooler.

Agreed. Trying to keep the car stock as much as possible. Even with it's flaws. Still might install an external cooler when it's all said and done.

 

[KeyKeeper]

Yeah its a tough call if restoring. Im going resto mod/drag so guess i have it easy lol.

 

[JoePeek]

I also never could get why an automatic routes the fluid through a hot radiator. I guess if the radiator temp is cooler than the trans temperature, there is some cooling effect, but nowhere close to a trans cooler where the temp difference is much better than radiator coolant. Maybe that is why I have a 4 speed. But all I know about automatics, espesially 4L60E's that I have rebuilt and tuned with HPTuners, don't think there are not times I would like to put a really build automatic behind my 455HO. But then I go drive that 4 speed, and would not trade it for an automatic, even though I think I could build an automatic that could keep up in the quarter with my 4 speed, there is something about banging gears that makes an old good running Pontiac a trip to drive.

 

[KeyKeeper]

Well I would agree that heating the fluid up in the winter time would be good for the seals and such in the trans...but damn once the trans heats up....

 

[TOMR67]

On our land rovers the trans and engine oil go through coolers in the rad, then through external coolers so summer extra cooling winter rad helps warm oils

 

[Zippy]

Trans oil can be too cold too. If running only in summer, you can just use a external cooler. But if you run in winter, -20 etc, then the tranny needs heat from the engine to warm it up. Once its warm its ok. I've had bad shifting to no shifting in cars here in winter that just had external coolers. I don;t run my TA in winter, so it's external only.