Auxiliary Transmission Cooler Placement

Sparky__70Dart340 said
Hi all,

Recently purchased 70 dart swinger with original 340 motor and trans, though I was told the cylinders may have been bored out.

Currently working on fixing the over heating issues. In street traffic (25 mph, streetlights, etc.) water temp is approximately 220-230f, but a few seconds on the highway (45mph and above) temp is brought down to 190-210f. Pull of the highway and quickly goes back to 220-230f.

This makes me think this is an airflow issue. And I suspect one large issue is this 11”x11” transmission cooler mounted between the fan and the radiator. Shown below with shroud on and off. Note the fan currently sits about 3” from the radiator.

1. Is the transmission cooler necessary? Can i just pull it out and rely on radiator to cool transmission oil?

2. If necessary, should it be moved? Its current placement makes me think it is killing any airflow give its size and placement directly in front of the fan.

Thanks in advance. New member here!

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Welcome aboard!

IMO, Professor Fate, he nailed it. Bulls eye.
You may very well easily live without that extra cooler. Even though a transmission works best at a warmed up temp, in general what a transmission likes is to be cool and shift quick. It’s not what the general public likes. Hence why the transmission is built the way it is.

All coolers should be in front of the radiator. Directly in the path of air flow. Car moving or not. I have found the factory cooling set up to be an excellent system most all the time with very few short comings, mostly round on over powering engines taxing the radiators capacity. Otherwise the radiator, proper shroud and a viscous clutch fan unit and fan blade work great.

This is exactly what I use on my hot rod E body 4spd Cuda. The small block makes over 430 hp & has 4.10’s. The OE radiator was recored and a new shroud with the MP Viscous clutch fan set up was used and I have not had a problem since. It’s been 30 years now. The car has run low 12’s. Sat in NYC rush hour traffic for hours at a time, travel hours at a time on the interstates.

Again, the professor nailed it.

Professor Fate said
1.) If you want to keep that trans cooler, move it to the front of the radiator. Keep it at least an inch away from the rad., more if you can. Keep it towards the bottom of the radiator, exposing as much of the rad. core to airflow as you can. A reasonable street driven 727 can live fine with just the rad. cooler, a worked 904 may benefit from the additional cooler. In general.
2.) Get rid of that 4 blade flex fan. That thing won't move enough air to float a paper airplane, let alone cool a bored 340. Try something like the MP viscous fan package, Mancini Viscous Fan Package Six or seven blade, hunt for your best deal. Try to space it about an inch from the rad. Fan should be 50% in the shroud.
3.) Matching fan shroud to the fan Mancini Racing Radiator Fan Shroud Again, hunt for best deal, new or used... links are for reference only, not endorsing anybody.