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05 express 3500 transmission lines to radiattor?

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Old Nov 16, 2025 | 11:13 PM
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Default 05 express 3500 transmission lines to radiattor?

05 express 3500 transmission lines to radiat

or?

anyone know which tube to splice into for the transmission cooler? top or bottom?

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Old Nov 17, 2025 | 12:03 AM
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I have a hunch that the lower is the feed and the upper is the return because that would eliminate trapped bubbles. You could always unhook both, crank for a couple of seconds, and whichever makes a big mess is the feed.
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Old Nov 18, 2025 | 8:59 AM
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Originally Posted by Triaged
I have a hunch that the lower is the feed and the upper is the return because that would eliminate trapped bubbles. You could always unhook both, crank for a couple of seconds, and whichever makes a big mess is the feed.
your hunch makes sense the top would be easier to splice into. maybe I could feel each tube whichever is hotter is the feed an the cooler is the return so the auxillary cooler will be inbetween the return. thanks

has anyone here w/ a 3500 installed a transmission cooler?


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Old Nov 18, 2025 | 10:14 AM
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When not under load the radiator heat exchanger actually heats the transmission fluid so just feeling for heat might get you picking the wrong one.
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Old Nov 21, 2025 | 2:10 PM
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05 chevy express 3500 which never had a cooler

​very little to no infor on these vans just silverados.

which has the trans tubes on rad.s pass. side vans are on the driver side

here's my plan cut the top of rad. tube out of rad go into the side mounted coolers bottom port, out the cooler top port back into the cut rad tube which is the return.

if it wasn't for the I think power steering on opposite side of rad. I'd eliminate the rad alltogether.



I plan an arrangment like this
on driverside where the trans tubes are on rad.



like isn't this how the rad.s builtin cooler works in though the bottom hot fuild then cooled out though the top back into trans. they refer to as return tube which I believe to be the input?
if it wasn't for the I think power steering on opposite side of rad. I'd eliminate the rad alltogether
thanks


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Old Nov 21, 2025 | 2:34 PM
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https://charm.li/Chevrolet/2005/Expr...20Flow%20Test/

This looks to say that the feed is the "front" line.

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Old Nov 21, 2025 | 3:39 PM
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that chart looks correct so the return is the rear trans fuild connection according to my image here.



so I'll trace the return line an splice there for auxillary cooler. then proceed w/ my plan cut the rad. tube (either top or bottom I believe the top ) out of rad go into the side mounted coolers bottom port, out the cooler top port back into the cut rad tube which is the return.

how doe's my plan of into the horizontaly mounted coolers lower port then out the upper port back into the return? thanks will report back.

this opposite side of rad. must be separated like there must be two differnt coolers. I was thinking trans fuild circulated on both sides of rad. but how can that be w/ differnt types of fuild.

I was comparing the van to my car which has a power steering cooler built into the upper rad. tube (absolute nightnare cleaning the cooling sys. when that dam cooler leaked into the cooling sys. took me years to figure out how power steering fuild got into the cooling sys. dam even after removing the dam thing years ago I'm still flushing crape out of the cooling sys. dam.

Last edited by the Brain; Nov 21, 2025 at 3:47 PM.
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Old Nov 21, 2025 | 4:00 PM
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Sounds good. If cutting a hard line to put a hose on I've had some luck using a double flare tool, just the first step and just slightly to make a slight bump at the end of the hard line so the rubber hose doesn't slip off. Otherwise just use 2 hose clamps rotated to not align and clamp fairly tight.
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