Auto transmission cooling lines - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Solver · 06-19-2002, 09:17 PM

I had to replace tranny lines on th350 does the top line on radiator go to top hookup on tranny? Someone told me one is pressure line and one is return line and they shouldn't be switched.

Longhorn Man · 06-20-2002, 12:30 AM

Not sure how it is supposed to be...but it doesn't really matter to much. If it is hooked up backwards, it'll just run through the cooler backwards.
If you want to be anal about it, figure out which one is the 'pump out' line, and hook it to the top of the cooler. That way, the fluid can cool a little more than if it were cooled, then run right beside your 200 degree anti-freeze. (that last part is why I don't think tranny coolers should be in radiators...200 degrees is the magic number for accelirated tranny wear)

JimKshortstep4x4 · 06-20-2002, 08:22 AM

The original routing is top of the radiator to the the upper fitting
on the transmission. I don't believe that it makes any difference, but we make our own lines and it is easier to route them this way, also.

Jim

Riptide · 06-20-2002, 09:57 AM

Just a thought but If you already have them loose I would plug the radiator lines and just get a separate cooler that mounts in front of the radiator. You can pick them up for around $30 bucks.

slam33 · 06-20-2002, 11:09 AM

Top to top and bottom to bottom, the bottom is the pressure side and you want to keep fluid in the line so that it starts primed. If you reverse it you would drain the fluid back into the trans when you shut down.

06-19-2002, 09:17 PM	#1
Solver Registered User Join Date: May 2000 Location: Storm Lake, Ia Posts: 1,449	Auto transmission cooling lines I had to replace tranny lines on th350 does the top line on radiator go to top hookup on tranny? Someone told me one is pressure line and one is return line and they shouldn't be switched. __________________ 1972 Cheyenne Super 20 LWB-Blue 1972 Cheyenne Super 10 LWB-Black 1972 Cheyenne Super 10 LWB-Red 1972 Cheyenne Super 10 LWB-green 1972 GMC 4x4 LWB-White 1971 Cheyenne 10 LWB-Ochre 1971 Cheyenne 20 Longhorn-Copper 1971 Cheyenne 20 Longhorn-Black 1969 Custom 10 LWB-lt blue 1968 GMC 3/4 ton-green 1968 1/2 ton swb stepside-silver 1967 Chevrolet CST 10 LWB-green 1967 Chevrolet custom 20 LWB-Maroon

06-20-2002, 09:57 AM	#4
Riptide Registered User Join Date: Apr 2002 Location: McPherson, KS US Posts: 102	Just a thought but If you already have them loose I would plug the radiator lines and just get a separate cooler that mounts in front of the radiator. You can pick them up for around $30 bucks. __________________ 67 Chevy C10 McPherson, Ks "Remember Don't Sweat the Petty Things, Pet the Sweaty Things"

06-20-2002, 11:09 AM	#5
slam33 Registered User Join Date: Aug 2001 Location: Long Beach, Ca Posts: 1,432	Top to top and bottom to bottom, the bottom is the pressure side and you want to keep fluid in the line so that it starts primed. If you reverse it you would drain the fluid back into the trans when you shut down. __________________ 71 LWB 350/350still working on it but it's going tp be sweet. www.geocities.com/stevemau/slam33page.html " TARGET=_blank>http://www.geocities.com/stevemau/slam33page.html?1004806705410 </A>

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06-20-2002, 12:30 AM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Not sure how it is supposed to be...but it doesn't really matter to much. If it is hooked up backwards, it'll just run through the cooler backwards. If you want to be anal about it, figure out which one is the 'pump out' line, and hook it to the top of the cooler. That way, the fluid can cool a little more than if it were cooled, then run right beside your 200 degree anti-freeze. (that last part is why I don't think tranny coolers should be in radiators...200 degrees is the magic number for accelirated tranny wear)

06-20-2002, 08:22 AM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	The original routing is top of the radiator to the the upper fitting on the transmission. I don't believe that it makes any difference, but we make our own lines and it is easier to route them this way, also. Jim



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