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Coolant Leak at Rear of Vehicle

Discussion in 'Chevy Trailblazer Forum (GMC Envoy)' started by spark96, Jan 10, 2007.

  1. spark96

    spark96 New Member

    I'm new to the site, but was hoping someone could help me out. I have a 2002 Envo XL, Ive had Decent luck with it, some problems I don't think it should have for its age, like the Fan Clutch that I just had to replace...but in any case I recently noticed a coolant leak at the rear of the vehicle, I guess its for the rear heating and cooling. Has anyone had this issue? Can the Heating portion be replaced without disturbing the cooling portion?

    Thanks in advance!
  2. ChevyFan

    ChevyFan Administrator Staff Member 5+ Years 5000 Posts

    GM did a poor design on the rear heat and they know about it. There were a couple of TSBs on it.

    If it's the heater core, that can be swapped out by itself.

    1) How many miles on your TB. 2) How much fluid is leaking? 3) Does heat come on in the rear still? 4) How long has it been leaking?
  3. ChevyFan

    ChevyFan Administrator Staff Member 5+ Years 5000 Posts

    Most likely the rear heater core got fillied with slush and backed up. It's possible that we're just talking about the tube that is cracked/leaking, etc.
  4. ChevyFan

    ChevyFan Administrator Staff Member 5+ Years 5000 Posts

    I'm not certain if this is related or not. I'm just tossing it out for general information.

    TSB 05-01-37-002, May 2005
    Poor Rear Heat Performance (Install Auxiliary Heater Pump)
    2003-2005 TrailBlazer EXT
    Condition: Some customers may complain of poor 2nd and/or 3rd row seating heater performance when the vehicle is at idle.
    Cause: This condition may be due to lack of coolant circulation to the rear heater core.
    Correction: Install auxiliary heater pump package. (P/N 89024885 L6, 89024886, V8) This pump will improve coolant flow to the rear heater core.
  5. ChevyFan

    ChevyFan Administrator Staff Member 5+ Years 5000 Posts

    I've heard that lack of coolant circulation over time can cause sludge buildup and the rear heater core can fail. I'd call GM pronto and see if they will work out a deal with you on this, even though it's out of warranty. They might pay for the part if you pick up the labor.
  6. spark96

    spark96 New Member

    Its a 2002 w/ Approx 55K miles. I notices it about a 2 months ago, just a little wet on the garge floor every now and again. A couple weeks ago I changed the Fan Clutch, and with it the Water pump, and Belt, Replaced the GM Junk Fluid w/ Green Fluid, ETC.... Now last night I saw a little more on the floor, maybe because its more noticable, because its the green or just because I'm looking for it.
  7. ChevyFan

    ChevyFan Administrator Staff Member 5+ Years 5000 Posts

    I hate to always look for the cheap fix, but I'd try some Alumaseal. :)

    GM has put out a TSB on this where they install an aux. heater pump to get more fluid to the rear heater core. Try giving GM a call to see what they say.
  8. spark96

    spark96 New Member

    Well another Engineering Marvel!

    :evil: Well I made some calls to get pricing on a replacement Heater core for the rear, because it seems like it will be easy to replace. I got a price of roughly $100, seems a bit high for a simple Heater core, but its manageable, but then the BAD News, Apparently in Pre 2004 Models they used a "Block Style" Connection, well they decided to change that somewhere along the way for some reason to a "Quick Connect". Well rather than making an adapter GM Decided that you should just purchase a new Line Set to the Tune of $300. Well that brings this bill to over $400 just in Parts (Discounted Cost). This All After I just got done replacing the Fan Clutch Last Month...And you all know how costly that is. A bit Crazy for a vehicle w/ 50K miles....
  9. 84fiero123

    84fiero123 Epic Member 5+ Years 1000 Posts Platinum Contributor

    RE: Well another Engineering Marvel!

    Is there anyway you can do the work?

    I would try to make an adapter my self. I made an adapter for my fuel pump tester so I can test the fuel pump after the filter.

    You need to find someplace that will get you the original block, fittings, or just change the whole end.

    It is a hose that runs from the front to the back, no reason you can’t put the new end on the hose at the end of the hose with a hose clamp.

    Napa sells a lot of fittings, for all sorts of connections.

    Or how about getting the old heater core repaired?

    It is still just a small copper radiator isn't it.
  10. unplugged

    unplugged Epic Member 5+ Years 1000 Posts

    The lines to my heater core began leaking under the vehicle. The line is a GM custom made line with a quick connect fitting. The line is big bucks from the dealer, but I went to NAPA and they have a replacement nipple. I just cut the connector off the factory line, and used a short length of heater hose and the nipple from NAPA. (pn:NBH9929) GM uses these at several positions along the heater hose route.
    [​IMG][​IMG]

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