Radiator Connection Leak

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by F E Knucklebuster, Dec 12, 2010.

  1. 2004 Chevy 2500HD w/6.0 Gas

    I have developed a seeping leak at a connection on the back part of the radiator.


    Any idea what is involved in taking care of this?

  2. stephan

    stephan Rockstar 4 Years 5000 Posts

    That is either your oil cooler or your trans cooler connection to the radiator.
    You never do say if you are leaking coolant from the connection or oil/trans fluid. If it's oil or trans fluid leaking, try tightening the connection. If you are leaking engine coolant there, & that is not a threaded pipe fitting, or a machined threaded bung with an exterior gasket,
    that can be resealed externally, then it will be a 2 piece connector with the seal inside & the rad. tank will need to be taken off, & have the connection resealed from the inside.

    ** Be sure & use a back-up wrench on the large fitting if you are going to try tightening the oil/atf line.
    Last edited: Dec 12, 2010
  3. Patman

    Patman Rockstar

    definatly a trans cooler line going in there. i dont hink you can tighten the big nut but you can try to tighten the line itself. but it sure looks like its coming from behind the big one... you may need a new radiator my friend. let me know how it all works out
  4. It's seeping coolant from behind the large fitting. Didn't know if I could replace a gasket or something to fix the problem. My first plastic radiator.
  5. stephan

    stephan Rockstar 4 Years 5000 Posts

    OK, plastic tank is the key word. I couldn't tell from the pic. 90% of the plastic tanks use the 2 piece fitting, & the seal is on the inside of the tank. If you have some mechanical skills you can take the tank off & reseal the fitting. You'll see some bent tabs holding the tank to the core. You need to bend these up a little at a time on the 2 short sides, & 1 long side. On the 4th side don't bend them as far as this will be your relocation side when puting it back together. Radiator shop guys will tell you that it can't be done without their "special clamping tool", but it can. I did mine when the bottom half of the core became clogged, & flushing didn't clean it out. The rubber tank/core gasket "should" stay stuck to the core, & don't move it, or remove it if it does, because this will make it easier to reseal it.

    **If the tank gasket does come loose, restick it with 3M "yellow" weather strip adhesive before trying to reinstall the tank.
    Last edited: Dec 12, 2010
  6. Byron P.

    Byron P. New Member

    Was having the same problem ! ! I even backed off nut, put forma gasket under nut, and re tightened. But it seemed like leak got worse ! ! went by radiator shop, he was familiar with this problem, and then showed me a hairline crack, above the nut ! ! I put a new radiator in ! ! ! ! ! PROBLEM SOLVED ! ! !
  7. j cat

    j cat Epic Member 5+ Years 1000 Posts

    The plastic side tank crack is the most likely issue with these leaks crack under the nut .
    removing the side tank is tricky on these . back in the 1980's you could buy a side tank and gasket set and the tabs where more robust for repair. the seals on these would be an issue . best buy new or scrap yard part.

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