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Do I need a new Radiator?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Boss, Apr 24, 2000.

  1. Boss

    Boss 1/2 ton status Author

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    Fellas, I posted a question about what temp. I should be running a while ago. The majority avg. said I should be running about 190-195. Anyways, My truck was constantly running about 210-215. I called a shop, (that has people I trust there) and they said that that is normal. Anyways, so I flushed the radiator with Prestone Super Flush(followed all procedures) and then I flushed it again with Prestone Super Radiator Cleaner, and got some rusted flakes out. So then I added 50/50 coolant/water. Now my damn truck runs about 230 after a mile or two, and then it will drop to about 210, and then back up to 220 again. Back and forth. Scary. What should I do? Any suggestions? Thanks.
    Oh, I have a new temp guage, new thermostat, and new GM Crate 350. If it matters.
    Boss
     
  2. Burt4x4

    Burt4x4 3/4 ton status

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    Just a guess, it sounds like the flushing you did jared loos the grap inside your rad. and now some of the channels are cloged. I would remove the rad. and take to a local shop and have it roded out the pressure tested! I did this when having cooling problems and it fixed my issue. I almost droped 250bucks for a 4core.I run at 185-195 now with a 3core! Good luck

    Rock ON![​IMG] 72 K5 [​IMG]
     
  3. OLDSTEEL

    OLDSTEEL 1/2 ton status

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    I agree with Burt. I had the same problem, and after I had it roded out it works like a champ. The shop told me the radiator was 60% clogged, hence the the hot engine. It only cost about $60, which saved me about $100 for a new one.

    74 K5

    Leave it like you found it, or better!
     
  4. NYC K5

    NYC K5 1/2 ton status

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    i just got finished with the same problem. check the radiator fins mine were so corroded that about half of them would fall out when i pushed them. things get old and rust, just go for the radiator now it will save you later. paid 173 for 2 core at pep boys
     
  5. Eric78K5

    Eric78K5 1/2 ton status

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    I agree with the others here. I had mine dipped and rodded out, and my engine ran much cooler. I flushed the system with prestone, just like you did, and started getting flakes everytime I checked it. So I flushed the whole system again, and then instead of driving it around, I pulled the radiator myself, and took it to the shop. Hope this helps.
     
  6. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    If you're going to go to the trouble of taking your rad to a shop to get it cleaned up, you might want to consider getting it recored. I have a 59 GMC half ton that ALWAYS ran hot. I spent the extra money and got them to recore it with a four channel core. It cost about $100 more than the dip and rod job, and I've never had a cooling problem since.
    Just a thought........
     
  7. jarheadk5

    jarheadk5 1/2 ton status

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    Once you do these things, consider using a product made by Redline called "Water Wetter". You can get it at Pep Boys. It improves the coolant's ability to absorb heat from the engine. It definitely works!! I used it in our '93 Laser (Pre-Blazer days) when we moved from CA to PA, in July, through the desert and over the Rockies on I-70. 113 deg. in Baker CA, a 2000 lb. trailer, and air cond. running full blast, and the temp didn't go over 220!! If you do use it, be sure to change the coolant before winter or it'll never warm up!!

    BTW, are you using distilled water? It helps cut down on sediment and corrosion in the system.

    [​IMG] Semper Maintenance!
    [​IMG] So many ideas, so little money...
     
  8. Corey-88K5

    Corey-88K5 1/2 ton status

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  9. SVBlazer

    SVBlazer 1/2 ton status

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    Had a 305 w/ a 2 core pulling a 5000lbs TT. Ran 220-230 (ok I was stupid!) Replaced both, 383 and 4 core. Run 170 or so.
     
  10. chaka73

    chaka73 1/2 ton status

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    look around maybe you can get a good 4 core for cheap I got mine for $40 it was old but it worked great, now my truck doesn't overheat at all good luck.

    keep blazin !!!
     
  11. 6.2Blazer

    6.2Blazer 1/2 ton status

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    It sounds like your thermostat is acting up. The rust flakes can get into the thermostat and make it act erradic.
     
  12. Boss

    Boss 1/2 ton status Author

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    Well, just to update yall, I took my truck to my most trusted shop to have them clean it and pressure check it for me. They did it for $50. Hopefully this will solve my problems. They told me my thermostat opens at 210. Isn't that a little high? I thought normally it should be like 180. Oh well, we'll see. I'll let yall know after I pick my truck up during lunch hour.
    Boss
     
  13. Boss

    Boss 1/2 ton status Author

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    Well, got my truck back from the shop and guess what. Exact same thing. But they said all is well. They cleaned and pressure tested and all. The shop dude said that if all else fails, then put a 180 thermostat in there, but that shouldn't really matter b/c my truck is not computer controlled. Well, I hope it just a bad guage or something, b/c I don't think I'm gonna worry about this no longer, wasted enough time and money on this as is. Just hope I don't blow a gasket or crack a block like the previous engine I had in there.
    Boss
     

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