BillyTz06

Which of the two transmission fluid lines going from the transmission to the transmission cooler in the radiator is the feed line? Is it the one going into the top of the cooler or the one going into the bottom of the cooler. I am installing an aux. cooler and I need to know which line is the feed to tie the new cooler into. My engine and trans is out of the car so I can't tell which one would be the feed line. Thanks

BillyTz06

BTW, its a '79 th350 trans

jb78L-82

If I was you, I would completely by pass the radiator using a tranny cooler if you use a mechanical fan that pulls air over the cooler constantly. I had a 73 Nova SS with the turbo 350 for years that I drove year round including 0 degree weather and never had an issue with running a big tranny cooler outside of the radiator-car had 170,000 miles on the original tranny when I sold the car . Tranny fluid gets VERY hot and severely taxes the cooling system.

I currently run 28,000 GVW Long double stack, not tube and fin, coolers exclusively to cool the tranny's in my 2001 grand Prix (110,000 miles) and a 1994 mustang gt (26,000 miles on the crap AODE tranny) and the setup works great and the cars always run cool and the tranny's are in great shape.

I would run the biggest double stack cooler you can get in the grille area outside of the radiator.

Hope that helps!

MrJlr

I'm running a tranny cooler on my '74...
VERY close to the hood when I open it....watch for that...

BillyTz06

Back to the original question please

SanDiegoPaul

I wish I had an answer but I have never had to figure this out. You are posting on the right forum, but I Suspect that a lot of us gearheads have never had to figure this out either.
if you don't want to call a local transmission shop, perhaps you could take a trip to the local library and open up a 70's motors manual.
Wish I could be more help.

jb78L-82

I don't know that answer for a turbo 350on a C3 but usually the top inlet of the trans line on the radiator is the return line on other GM cars-Sorry I cannot be more specific.

DRIVESHAFT

The lower port on the side of the trans is the feed line.
The top port is the return.

BillyTz06

Thanks for the answers. The bubba way to tell which is the feed line is to start a cold engine and let it run for about a minute to five minutes while feeling the lines with your hand. The feed line will get warm to hot while the return line will remain cool. Of course the longer the engine runs the hotter both lines will get, that is why you have to feel the lines within the first minute or so. Anyone want to try this just for fun?

'75

Answers here http://forums.corvetteforum.com/c3-g...which-way.html

aussiejohn

[QUOTE=BillyTz06;1577487133]Thanks for the answers. The bubba way to tell which is the feed line is to start a cold engine and let it run for about a minute to five minutes while feeling the lines with your hand.
Billy,

The Bubba way to tell which is which is to DISconnect both lines at the radiator, then start the engine and have Mrs. Bubba tell you which one is squirting red fluid!

And as this method only takes a few seconds, it wastes less fuel too!

Seriously, I have read in my Holden manual that the fluid always ( in GM cars, anyway ) flows into the LOWER opening and out the TOP. One reason is that hot fluids rise, so why fight physics, but the main reason is that any air bubbles in the ATF will tend to rise, so it makes sense to pump the fluid in at the bottom, and any air bubbles will rise and come out the top hose and go back into the transmission.

To pump the ATF (with air bubbles) into the top fitting will force the bubbles downwards when they want to flow upwards, so you could have air bubbles in the cooler for long enough to minimise the heat transfer from the ATF into the radiator.

Hope that helps.

Regards from Down Under

aussiejohn