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Heater Core

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Crash90K5, Mar 9, 2000.

  1. Crash90K5

    Crash90K5 Registered Member

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    Funny one of you should mention a leaking heater core a few posts back (Blazer79). This week, I've been having a hell of a time with my windows fogging up, and my passenger side floormat is soaked. Also, when I through the defrost on high, steam or something was coming out of the vents. I believe it's the heater core (water on floor has greenish color). I don't know where to start, and was hoping someone has done this before. Do I have to pull the lower dash out? Is all the work done inside the cab, or is there stuff to do in the engine bay? If the cheapest solution is junk yard, what years would be a good donor, in other words were they all the same, or specific to my year (1990). Any help, and additional info would be great.

    [​IMG] <font color=blue>Crash90K5</font color=blue> [​IMG]
     
  2. Goose

    Goose 1/2 ton status

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    Don't know the procedure for the '90 Blazer, it's a little too new. I wouldn't get one from a salvage yard. I would go through a dealer or maybe a auto parts store. On my '73, the auto parts store cores would not bolt up tight so I had to go to the dealer. The dealer part made the auto store part look and feel like a tin can with some fins stuck to it. It also cost $100. I guess you get what you pay for.
     
  3. 78Blazer

    78Blazer 1/2 ton status

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    Mine also went out in my 78 blazer, I called around and I think it was only like 35 bucks they wanted for a new one..

    Scott
    78blazer
     
  4. Esteban86K5

    Esteban86K5 1/2 ton status

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    You have to take you glove box out and that exposes everything. Remove all the vent, vacum lines and levers and remove the 4 or 5 bolts from the engine bay and the heater assembly will pull out. Everything except the bolts is done from the inside. I bought a new heater core from pep boys and it didn't look to much different than what it had and it wasn't 100. If you don't already have one, get a haynes manual for your truck. It goes into detail ut it. Good luck.

    Esteban
    SEMPER FIDELIS TO MY BLAZER
     
  5. Mr Red

    Mr Red 1/2 ton status

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    I did this chore around Xmas. Don't know if 90 dash & assembly is the same as mine. I'll check my Haynes & Chilton's after dinner & edit the post as necessary.

    This is not something you buy used because you sure don't want to do this job again-if you do it yourself. Go to an old fashioned auto parts store (that's been around for many years-NOT Smak Auto or P** Boys) or NAPA & try to get a replacement that's all metal/aluminum. Mine came w/ lifetime warranty[keep the papers]. A lot of the new ones have a composite piece on each end-just doesn't make sense to me to try to bind composite/plastic and metal on something like this. And, before you put it in, pressure test it w/ your garden hose-plug one outlet on new core and work an old hoes end over the other, clamp the outlet down and flow water with the outlet plugged with your thumb {press hard). Obviously, there shouldn't be any leaks!

    You have to remove the entire vent box under the dash to access the core. Make note of what screws go where and maybe take pictures of the position of cables before you take the off of the vent box. You'll have to pull hoses under hood. Make note that they may not be the same size-write down which goes where & go buy new hoses [take old ones with you].

    If cooling system hasn't been flushed every couple of years, you might want to get ready for the radiator to let go. Good rule of thumb is flush every two years (or annually for heavy use) and change themostat at that time.

    If I recall correctly, the job took about 4-5 hours. I had trouble locating some bolts and have got to tell you, it's not a lot of fun. My mechanic said the labor charge was only like 1.5 hours but I know mine was done right.

    Good Luck,
    <font color=red>David, '86 K5</font color=red>
     
  6. Crash90K5

    Crash90K5 Registered Member

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    OK, you guys aren't making me feel good about doing this. I hate ripping out half the truck to get to a really stupid part. [​IMG] Oh well, I ain't gonna pay up the a$$ for a simple fix. Now, If I'm hearing Mr. Red correctly, I'm going to be pulling hoses from cooling system? Also, I found in carparts.com a couple of cores: one was $20 from Four Seasons, and the other $30 from Modine. Has anyone heard of these brands? I wish I had caught this sooner, I need my rig to head up to the snow this weekend, and I'm going - fogged windows or not!!! [​IMG]

    [​IMG] <font color=blue>Crash90K5</font color=blue> [​IMG]
     
  7. 3030

    3030 Registered Member

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    replaced mine on my 80 k5 one year ago. Cost about 40 bucks and took all day, but I'm not mechanical at all. Had to take out everything under the passenger side dash. Also had to remove the right front fender to get to some of the nuts on the engine side. I never did get the vent ducts to go back flush. Wasn't worth it to me. I would take it to someone else if I had it to do over again.

    There ain't no way I'll get stuck in that hole.....oops.
     
  8. Mr Red

    Mr Red 1/2 ton status

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    You shouldn't feel good about it. The job sucks. The part isn't stupid, especially if your headed into snow-no heat without it & if you don't replace it, you'll run out of antifreeze and toast (or freeze) the motor. Yes, there are hoses: two-one to the intake manifold & one [larger of 2] to the radiator. Replace them unless you want old gunk going into your brand new core.

    Never heard of the two mfgs of cores. That doesn't mean anything though. I already gave my 2 cents worth on where to buy one.

    I've attached some screen shots of general directions off a CDROM repair manual. WARNING: THIS IS FOR AN '86 YOURS MAY BE DIFFERENT.

    Good Luck,
    <font color=red>David, '86 K5</font color=red>
     
  9. mudfanatic

    mudfanatic 1/2 ton status

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    If you climb underneath the truck you can get to one of the two difficult nuts, the other one is just a pain in the a##, you can't see it, just reach around the right hand side of the AC box on the firewall and you'll feel a stud back there, work off that nut (I didn't replace this one on mine)[​IMG].
    I bought my heater core at a radiator shop, bought a brand new one and they pressure tested it for me before I left the shop $36.00
    3 hours and I was back on the road, but I have done heater cores before- I have to say that Fords and Volvo's have the hardest heater core's that I have been involved with.
    '77 K5

    <font color=red>mudfanatic</font color=red>[​IMG]
     
  10. Eagle86K5

    Eagle86K5 1/2 ton status

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    I recently did the same job...these brothers are telling the truth. Hardest part was getting to the bottom bolts. I went and bought long extensions and a universal joint and some deepwell sockets. Get a small step ladder and just about crawl into the engine compartment. Not a pretty site but well worth the effort....heat....no fog....and no nasty smell of antifreeze.

    <font color=green>Eagle86K5
     
  11. delta9blazer

    delta9blazer 1/2 ton status

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    snow trip?

    <font color=purple>delta9blazer</font color=purple>
     
  12. Matt N.

    Matt N. Registered Member

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    Modine is a good quality brand. Probably the largest maker of aftermarket radiators around. Four seasons is a lower end company, but their stuff I've never had a problem with. Murray makes good stuff too. I would probably get the Modine if I had the choice. I will be replacing mine when I swap the motor, so it's just 'round the corner. My local parts store wants $32.99 for it. Dunno what brand it is, though...
     
  13. Matt N.

    Matt N. Registered Member

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    Never changed one in a Saab, have you? This is the basic way the manual runs...
    1. Remove negative battery cable.
    2. Remove Engine.

    it goes downhill from there.....
     
  14. Goose

    Goose 1/2 ton status

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    Saab? sucks to be you. On my '73K5 w/out AC I can do the entire job in about 2hrs. Gotta love the older K5's
     

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