Coolant not circulating!?

Discussion in 'Chevy C/K Truck Forum' started by GMANs95, Oct 31, 2013.

  1. GMANs95

    GMANs95 Member 1 Year

    Just replaced the thermostat and temp sensor on my 95 350 c/1500. Getting proper temp reading on gauge, but the rad hose is hard (dont go there) as a rock.
    New coolant blah blah blah. It is inserted correctly (spring down) and it is the OEM temp rating.

    What am i missing? :grrrrrr:
  2. JTWard

    JTWard Rockstar 3 Years 500 Posts

    Is the upper or lower radiator hose as Hard as a rock ? If you remover the radiator cap when the engine is cold, then start it and watch to see if your coolant begins to flow across the radiator. But I'd say you have a clog somewhere, and i'd doubt the sending unit is telling the truth.
  3. GMANs95

    GMANs95 Member 1 Year's a new radiator too. Sending unit is brand new.
  4. j cat

    j cat Epic Member 5+ Years 1000 Posts

    what was the problem before you changed these parts ?

    thermostat could be defective. sender could be the wrong one .

    what is the operating temp when heated up ?
  5. GMANs95

    GMANs95 Member 1 Year

    As far as I know there was no problem. (see my introductory post) When I got the truck the engine was shot. (spun bearings) I put a "new" reman 350 in it. Thermo is new...sensor is new, radiator is new. Thermostat is a 190.....and the temp reading is 2 notches below the printed 210 on the gauge.
  6. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    What's the condition of the water pump?

    Did you reuse the old one?
  7. GMANs95

    GMANs95 Member 1 Year

    Good visually checked ok......didn't see any sign of leakage at the weep hole....and there is no sign now. Have about 300 miles since the motor swap.
  8. JTWard

    JTWard Rockstar 3 Years 500 Posts

    I know it's a new engine, but if you pour water into the top of the radiator, does it come out of the bottom ? The reason I ask, is if the thermostat is working, (And I have no reason to think it's not) then it seems the upper radiator is pressurized, but it's not flowing through the radiator ? And I don't mean any disrespect, but there wasn't any plugs left in the cooling system anywhere right ?????
  9. GMANs95

    GMANs95 Member 1 Year

    No disrespect taken. I too am originally from a small town north of skin is thicker than most. I am going to take the lower hose off in the morning to see if it indeed drains. which way does the fliud flow? Top to bottom thru motor or bottom to top thru the radiator?

    When I get in it in the morning there is no pressure in the hose....when i get to my destination it is pressurized. What about taking out thermostat and seeing what happens? Recommended or not......
  10. JTWard

    JTWard Rockstar 3 Years 500 Posts

    Well the Corvette is the only 1995 GM vehicle that had reverse cooling that I know of, so I'm going to say it a conventional system in the top and out the bottom and up thru the engine again. But never the less, the radiator in your truck seems to me to be the biggest unknown here. For all intensive purposes I can't keep thinking it's working and the new engine has super clean coolant cavities so that leaves us at the thermostat, which seems to be working as the upper radiator hose gets hard, (I'm guessing it's pressurized which is why it's stiff) so that leaves only the radiator as the culprit. It's got plastic tanks on both ends, but it might be clogged and the only way to find out is drain the cooling system and see what kind of flow you have ?

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