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Transmission cooling lines

Discussion in 'Chevy Trucks' started by Chevy 1500, Sep 16, 2007.

  1. Chevy 1500

    Chevy 1500 Member
    Messages: 30

    I just spotted a few drops of tranny fluid in my driveway and looked under the truck and saw some tranny fluid on my cooling lines right above the skid plate. The lines are rusted really bad and there seems to be a small leak there. Can anyone tell me how hard it is to replace the two lines? Do i need to drain the tranny fluid first as well. The truck is a 2003 Chevy 1500. Thanks.
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    They can be a pain to swap out the complete lines as they're pretty long with lots of bends which makes it hard to snake the new ones through the chassis but it's a job most anyone can do with a few tools and a floor jack. If they're only rusty in a short section you can cut out the rusty section and slice in a new section of line with a few compression fittings but if they're really bad, I'd recommend just going a head and replacing the entire line. Be forewarned though, they are pretty expensive from the GM dealer, which is the only place you'll be able to buy the complete line as an assembly. Draining the trans to swap the lines isn't necessary btw.
  3. JayMac

    JayMac Member
    Messages: 95

    I have a couple of trucks older than yours. So I don't know how hard it is to replace your lines, but check out,


    They are reasonable on price and I have ordered from them many times in restoring a truck and replacing parts on my work truck. Look'em up.
    Last edited: Sep 16, 2007
  4. dlcs

    dlcs 2000 Club Member
    Messages: 2,160

    The cooling lines are a pita to change. My dealer changed mine on my 99 Silverado 2500. The process took 1.5 hrs. The problem was they couldn't get the lines off the oil cooler and we ended up changing the adapters too. i was glad i just let the dealer take care of it.
  5. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    It depends on how good a wrench you weld. It can be done but you need to be careful with what you are doing. Take one line off at a time,keep it in the same shape and bends as you can. Buy the same size line and a bit longer then it is.You will have junctions, they don't sell pieces big enough to go the whole way. Use a line bender to imitate the bends on the old one. Buy a couple of styles to do the job. Do not kink the lines. If the hold downs for the lines are destroyed use heavy wire ties to anchor it to places.If you can't afford to do it right now or don't have time, I would patch it. Find out where it's leaking,buy a small block tubing cutter. Cut out the section with the leak in the middle.
    Put a section of transmission tubing in it's place with screw clamps. You don't want the line to pop while your driving. Most transmissions take 10+ quarts to operate.Do you have fluid and repair parts?Most transmissions die after losing pressure while in motion.
    I had a line pop and it looked like I hit a huge deer, red steaming fluid dripping off the front end.
  6. stillen

    stillen Senior Member
    Messages: 247

    These two lines utilize the quick connects, I just did mine. please email me at mikestill@5615.com, and i'll send you the diagrams and parts list that you need.... The hardest part was snaking the lines in and out of the underneath........... I highky recommend replacing the four connectors which are quick connects, they come from the factory with thread tape already on them, you just remove the old and screw in the new. The lines simply snap in. Also be sure to replace the four retaining clips that hold the two lines together. Ill send you everyhting i needed, hopefully making it easier for you.
  7. mike0955

    mike0955 Junior Member
    Messages: 20

    I just did them on my 99 silverado, as it has been said before, they are a pain to do. I bought the whole lines from gm for $18 each, and it took about 2 hours to do, on a lift. Make sure they are adjusted well after you get them in so that they don't rub on anything or each other.