transmission cooler lines

Joined
Aug 7, 2009
Messages
45
Location
Iowa
Does anyone know which line on a 2003 chevy silverado is the pressure line and which one is the return line back to the tranny? I'm wanting to do an at-home flush and would like to know which line to take off to drain into the bucket! Thanks Justin
 
Joined
Mar 24, 2007
Messages
10,008
Location
Upstate NY
Get two pieces of hose, connect them over the disconnected lines, put the ends in buckets, and have somebody crank the engine for a second. You'll find out quickly then! On my 99 LeSabre the top hose is the return hose.
 
Joined
Jun 25, 2009
Messages
4,065
Location
Chicago, IL
does it have a cross-flow radiator? theoretically the line that is closer to the radiator return hose is the return line. you should also be able to tell the difference by feeling the temperature of both cooler lines - the cooler one should be the return line. obviously be VERY carefull doing this.
 
Joined
Dec 5, 2003
Messages
6,990
Location
Everett, Washington
 Originally Posted By: sciphi
Get two pieces of hose, connect them over the disconnected lines, put the ends in buckets, and have somebody crank the engine for a second. You'll find out quickly then!
I agree........ I have hooked up the wrong end when I thought I had it right before, it's not fun. So now I just hook both ends to containers and verify with flow.
 
Joined
Dec 2, 2002
Messages
6,388
Location
Washington St.
You don't need to run the engine, just crank it. You can disable the engine by removing the coil wire or pulling a fuel injection fuse. Less messy when just cranking....
 
Joined
Sep 28, 2002
Messages
39,802
Location
Pottstown, PA
Find the one that attaches to the transmission furthest back. That should be the return line. The OUT line should be nearest the converter. But if you've got hard lines ..that's not the line you want to unhook UNLESS you're doing it at the trans. You want the line FROM the trans UNLESS you're going to attach a hose to the fitting somehow. You may find it easier at the trans.
 
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