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Help !! 1990 Suburban Heater Core !#@&$#@

Discussion in 'The Garage' started by MOLON LABE, Apr 17, 2006.

  1. MOLON LABE

    MOLON LABE Registered Member

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    Ok, this will be the third heater core in five years !!! :mad: :mad: :mad:
    This vehicle is a cream puff 1990 1500 5.7 4x4 with 45,000 original miles and both previous heater cores were factory GM parts.
    This vehicle was well maintained before I got it and I'm very big on preventative maintenance so it gets regular service including the cooling system annually.
    My first question is.....is there a better heater core available than the factory part ??
    Second, are ther other things, possibly other factors that could contribute to their early failure ?
    I'm thinking I might have a electrical problem which is causing it to corrode. Any known places to look fot this type of problem ?
    Third, for similar vehicles that don't have heat, what was used to block the hose fittings ?? How could I just eliminate the heater since I never use it here anyway ?
    Thanks for any advice.
     
    Last edited: Apr 17, 2006
  2. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    I'm still using a stock 20 year old heater core, but if I had to replace it, I'd probably buy an aftermarket unit with a lifetime warranty. Hopefully someone can recommend a brand (I think Ready Aire is one, but I can't speak to the quality either good or bad).
     
  3. wayne

    wayne 3/4 ton status

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    If you don't need the defrost of heater you can go to the parts store and get a fitting to just put the 2 hoses together and bypass the core. I had to do it on my DD 90 K5 untill I feeel like spending the 2 hours swappint the core. In my other 90 I replaced the core over 3 years ago with one from Napa and never had a problem with it yet.
     
  4. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    I've replaced the core once on my '91. You could be onto something with your elecrical theory though. Check all chassis to body, motor to body earths. I can't remember if the core is rubber mounted or not so you may want to look into whether the core should be earthed too.
     
  5. MOLON LABE

    MOLON LABE Registered Member

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    Does anyone know the locations of the ground straps and ground points for this vehicle ?
     
  6. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    I could be wrong, but I believe the main engine block ground strap is usally off the rear of the passenger side head, and runs to the firewall.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Where and how is it failing?

    If it's a fatigue issue, your hoses are clamped to the fenderwell as stock, right?
     
  8. Leper

    Leper 1/2 ton status

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    I wonder if his ground strap is attached directly to the core or its mounting box.
     
  9. mouse

    mouse 1/2 ton status

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    The '89 sub I bought for the TBI components had its heater core go too. It was advertised as needing a headgasket and a heater core.

    From the looks of things, this one exploded inside and covered the carpet in coolant (it was otherwise a beautiful interior).

    I have seen heater cores go in cars that people have used some sort of coolant additive to stop a radiator leak.
     
  10. MOLON LABE

    MOLON LABE Registered Member

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    Well I took some advice from above and bought a 3/4 to 5/8 adaptor and just hooked the lines together for now.
    I took a volt meter and tested the inside of the radiator and there was voltage present. The inner core of the rad was also oddly corroded. Not like normal corrosion so i think the electrolysis issue might be the problem.
    A possible cause for this is the bare (from the factory) ground strap at the rear of the block on the passenger side which attaches to the firewall. The ground strap was laying right on the metal heater tube that feeds on of the heater hoses to the heater core. The was visible marking on the spot wher they had been making contact.
    I will test it again tomorrow and see if the voltage comes and goes as I touch the ground strap to the tube.
    We'll see what happens.
     
  11. Blazer1970

    Blazer1970 1/2 ton status

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    You are using anti freeze aren't you?
     
  12. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    I'd just like to say that changing a heater core, in most vehicles, is one of my least favorite repair ops. :angry1: I'm pretty sure that I'm not alone with that sentiment.
     
  13. sled_dog

    sled_dog 1 ton status

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    if he doesn't have A/C in a 1990 Burb, I can do it in 30 minutes... thats all it took me to do my first one. Its way easier than you would expect.

    Now on a newer Mitsubishi, one of the guys spent an entire 8 hour shift yesterday puting one in. And I don't think he was done at the end of the day. I was too busy with MY least favorite thing, a steering columns inners :doah:

    I know you are only doing it temporarily but for Wayne's note, you have to have defrost for inspection :wink1:. Of course up to whoever inspects it, but first thing I do when I inspect something is flip it to defrost and crank it up.
     

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