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  1. #1

    Default Transmission Coolant Lines "Seeping" according to Dealer

    Hey Truck Pros,
    I know I'm a noob but I read a lot on here and would like to ask for a little input if possible. Today I took my truck in for it's first oil change at a Chevy Dealer since I bought it earlier this year (2003 Yukon XL 5.3). I love this truck and am very pleased with it so far.

    Anyways, I also opted to have the Fuel Filter replaced and the Transmission Filter/Fluid changed - all for maintenance just because i figured they were due or overdue.

    The dealer calls and claims I need 2 new belts (alternator and something else), Power Steering Fluid Flush, Brake Fluid Flush AND that all 3 of my Transmission Coolant Lines are "beginning" to seep and they should all be replaced.

    The Dealer Quotes are:
    Transmission Filter/Fluid (no flush) - $150
    Fuel Filter/Oil Change/Tire Rotation - $120 (what?!?!)
    The belts were quoted at $175
    Power Steering Flush - $118
    Brake Fluid Flush - $138
    3 New Transmission Coolant Lines - $607!!!

    So anywho, I elect to go ahead and do everything except the transmission lines for a hair over $700. This is steep but it's at the dealer and whatever - I can at least do my own oil changes moving forward.

    My question is - can I ask this group how critical it is to replace these Transmission Coolant lines? I'm remotely knowledgeable about vehicles and I understand these are for cooling the tranny and I guess it's tranny fluid seeping out ever so slowly. The dealer rep said I could technically just keep an eye on the tranny fluid level but that "they could break". He explained the seeping is where the metal meets the rubber I guess.

    In addition, the truck has about 160k on it, and the transmission doesn't seem to be perfect (little hard 1-2 shift when warmed up, slight delay once in a while when downshifting). I do plan EVENTUALLY to get a full rebuild of the tranny and possibly replace the coolant lines at that time.


    Any input would be appreciated!

  2. #2
    Jr. Apprentice
    Join Date
    Apr 2014
    Lake Gaston, North Carolina


    First of all, welcome. The transmission filter and fluid change sounds reasonable, but the belts for $175? You can get them at Autozone cheap and they're easy to change. The transmission coolant lines should be metal and there is no reason they should be bad unless they're bent or kinked in some way. I would pressure wash or clean their attachment points well and watch for leaks. Sounds like the service manager is seeing you as cash cow. As for the fuel filter, with the advent of ethanol, I change mine yearly. The job does require special tools readily available at Autozone and they even print you out instructions on how to bleed off the fuel pressure and remove the lines for filter change. Once you've done one it is easy.

  3. #3


    Thanks for the response 98SubDriver! Yep $175 seemed steep to me too, they claimed that each of the 2 belts was around $55 each + labor. I'm comfortable with the rest of the work.

    However, for the transmission coolant lines on a 2003, I do believe that they are not all metal. There seems to be some Rubber Type of crimped fitting that is apparently notorious for leaking - I'm assuming others on here have encountered this?

    I found this post regarding a 2007 and it has another person commenting that it happened on their 2003 - it really seems to be an issue that can cause the tranny to fry:

    Any feedback would be appreciated from anyone! It does seem that these lines are ~$20 each but are a PITA to install I guess. I will likely take it to a non-dealer auto shop and get some quotes. $607 is ridiculous and in the post above the guy even confirmed that the Dealer was overcharging etc.

    Just kind of irritated with this - but am about to go pickup the Yukon within the hour. Hope everything else is fine.

    Thanks all!

  4. #4

    Default are 2 Diagrams, just to show you where and how the Transmission Hard-lines are Routed, and does your Yukon have the Factory Transmission Cooler?? its Number #13 in the First Diagram.....also you mentioned "There seems to be some Rubber Type of crimped fitting that is apparently notorious for leaking".....I'm guessing but I think that this may be Number #2 in the First Diagram.

    In This Diagram with the Transmission Hard-lines, with the Factory Transmission Cooler

    In This Diagram is the Transmission Hard-lines, without the Factory Transmission Cooler,


    5.3 l 3.73 l G80

  5. #5
    Jr. Engineer BRB46's Avatar
    Join Date
    Apr 2011
    Western Mass


    I have an '06 and mine are wet where the rubber meets the metal. I bought all three lines at the dealer for $94.00. Haven't changed them yet but watched some how to videos on Ytube. It doesn't look too difficult. I have been waiting for the garage to warm up so maybe this weekend I will get to them.
    2006 Silverado 1500 5.3L ecsb Z71,afe pro s dry air filter, color matched tailgate handle and bezel,color matched front bow tie, led interior illumination, 5000K HID lows, Black powder coated wheels, Blacked out body side moldings, Rough Country 2.5" level/lift kit, Magnaflow muffler

  6. #6


    99'HEARTBEAT - thank you! I am 90% sure it's the first diagram with the cooler, but that is really only because it seems #2 on my truck is curved upward instead of a straight in to the radiator as in the 2nd diagram. Also, if I'm reading this correctly, it seems the 2nd diagram may only have 2 lines? If so, the dealer did say I needed to replace all 3 if maybe that helps determine.

    Also to note, yep I do believe that #2 is the spot where I can visually see it wet/damp. It seems like most of the lines around that area are wet as well, so at least the dealer wasn't completely bs'ing me.

    I'm reading that some people literally cut these fittings and apply other connectors to resolve, some are replacing and have the same probs and some are replacing with "better, improved OEM lines". Any insight here would be awesome. Or if I can go out and try to determine anything else, I'm happy to do so.

    BRB46 - that's awesome to know that even for the factory lines, it should only run about $100 for parts. I wonder if I could find a shop around here willing to do just labor jobs...

    P.S. - can I ask if it's normal to have a "tighter" steering feel after replacing the belts? It makes sense to me if it's tighter belt with less play. Also after they rotated my tires, I swear my ride feels a little less smooth - perhaps my tires weared unevenly.

    Or perhaps I'm being a sensitive pansey and am now opening up my dog ears for the look and feel of everything.

    Thank you again all, I really enjoy these forums and you all have some beautiful rides!

  7. #7


    the ride may not be as smooth if they rotated and did not balance them. The trans lines are not hard to change at all. You don't even need the special tool, but it does make it a lot easier.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  8. #8


    YukonXL2003......If you go and Look through the Grill on your Yukon, and if you see this Small Factory Transmission Cooler(Pictured Below)then Diagram Number #1 is your Setup, if you don't see this Small Transmission Cooler, then your Setup is Diagram #2

    Factory Transmission Cooler

    You have a few Routes you could go, as you mentioned by, cut these fittings and apply other connectors to resolve, some are replacing and have the same probs and some are replacing with "better, improved OEM lines".......without being able to see a picture or two(not your Fault)its going to be a little hard for me or anyone to say, Do it this way or that way, to fix this issue your having??......But if it was my Truck, I'd go with "better, improved OEM lines"......

  9. #9
    TRPLXL2's Avatar
    Join Date
    Jan 2009
    Norwalk, Ohio
    Blog Entries


    I replaced all my transmission lines with Russell fittings and braided stainless line. Cost me about $150, and a little bit of patience. They make fittings that screw right into the radiator/transmission . I wouldn't even waste the time replacing them with oem lines, your going to have the same problem again down the road.
    2004 Chevy Colorado
    LS1 5.7 swap/TBSS rear axle swap

  10. #10
    Sr. Apprentice
    Join Date
    Mar 2014
    green river wy


    The manufactured crimps at notorious for seeping a quick fix is to grind the crimp and buy hose clamps and do away with the crimps you will also need to flare the metal lines so they don't blow off but for some reason they do break you have the chance of burning your trans up

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