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Temperature fluctuations in my cooling system

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  • #536368
    ScottieScottie
    Participant

      Maybe one of you guys have experienced my problem before.

      Background
      I own a 1996 Suburban K1500 with the 5.7L Engine. I bought this truck last year and noticed the radiator tank leaking slightly. No big deal I said to myself I’ll just replace the radiator when I get the money together. So this summer I am towing my small camping trailer, I notice the temp climbing towards 210 degrees I pull over let engine cool and determine that now the cooling system needs service.

      Replaced
      What was done…new radiator,new water pump, new fan clutch, new thermostat(Stant Superstat 195degree), new belts, hoses, tensioner and idler pulley. Also new oil cooler lines and a new oil filter adapter and fittings(to stop oil leaks)

      Procedures
      I had flushed and back flushed both heater cores(The old coolant was nasty it needed to go)…good flow. I pulled the block drains and flushed the block through the water pump ports and through the open thermostat hole in the intake. All clean. Refill system 50/50 dexcool. Used spill free funnel to refill and bleed air out of system. I am pretty sure all the air is out.

      Modification
      The only thing different here than what was in the truck was the replacement radiator I bought from a local 1800Radiator shop (lifetime warranty) The old radiator was the 1 1/8 single pass core and I replaced it with the 2 1/8 double pass core that was for the 350 or 454 figured it would give me more surface area for low speed towing.

      Problem
      The temperature doesn’t seem to be able to stay stable at the 195 degree setpoint. Upon first warmup it will sometimes climb to 199-205 degrees and cool down to its 195 setpoint.(I am taking the temerature with my OBDII code scanner in MIL Data mode….The temp of the code tool matches what the gauge is doing) I have owned three chevys of this generation and all of them the temperature would stay consistent after hitting the setpoint unless it was 110 degrees out and the cooling system was under heavy load. In this situation you could see the needle rise hear the fan clutch kick in the engine would shed its heat and everything would return to op temp.

      My question is I guess, what the heck would keep this truck from staying at a consistent 195-200 degrees. Should I just ignore the fluctuation as long as it doesn’t go any higher or is there something else Im missing here

    Viewing 4 replies - 1 through 4 (of 4 total)
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    • #536443
      college mancollege man
      Moderator

        with all the work you did you may have air in the system.

        https://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats

        #536445
        BretBret
        Participant

          Possibly the type of coolant? all i can think of but maybe seeing new radiator might take certain kinds of coolant but idk just a suggestion

          But really i would’nt worry toooo much about the fluctuation of the temp unless it causes some major mechanical issues

          just keep an eye on it =]

          #536465

          A couple of things you could be looking at here so let’s start with the basics.
          1. Air in the system. I have come across so many cars with problems like yours and it came to air bubbles circulating in the system.
          2. Bad coolant temp sensor. I’ve seen a couple of these go after seeing customers replacing major components as they get overwhelmed when full pressure is restored to the system.
          3. Faulty thermostat/thermostat o-ring. Like anything there can be that 1/1000 that’ll be fucked from the shop. Weather its not opening properly or maybe part of the o-ring has become lodged.

          #536579
          BillBill
          Participant

            I have seen this happen before. I know you changed the thermostat but who really knows where it was made. I believe Stant makes em for Napa which is about the best as far as aftermarket stuff goes. I really wouldn’t worry about it as long as it doesn’t go too high but if it bothers you try a Delco stat.

          Viewing 4 replies - 1 through 4 (of 4 total)
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