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Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by jwduke, Apr 15, 2002.

  1. jwduke

    jwduke 1/2 ton status

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    Location:
    Ice Cream Capital of the World, IA.
    Can some one tell me whats wrong here........ My '87 (Has a 305 yuk), when it is cold (-10), it runs cool (180 deg. maybe), when its hot (90 deg. 35% humidity) it runs 210 to 215 deg. I'm running it in drive, not OD. This temp is with the A/C on. I've changed the thermostat twice, both times with a 195 degree thermostat. Any ideas? I'm thinking of changing the water pump (Clock has 73,000 actual miles). Would the clutch fan have anything to do with this? It isn't loose or anything.........
     
  2. Hossbaby50

    Hossbaby50 3/4 ton status

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    That is not that unnormal. My truck runs 185 when it is 50 degrees, and when it gets to 90+ it runs around 205-215. You could flush your radiatior, or have it flow tested to make sure it is flowing right.
     
  3. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Does it ever get hotter than that? no. Fuel injected engines are supose to run about what yours is. If you go and try to get it colder it may not go into closed loop and run off the cold start fuel curve. get bad MPG. If it has high miles put a O2 sensor in it if you don't know it has less than 50 K on it.
     
  4. jwduke

    jwduke 1/2 ton status

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    Grim..... If it is like 95+, and you run on the interstate, at like 80 mph, it will climb up to 230 deg. This is with no load.
     
  5. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    That is too high. Do you mud the truck? Sometimes crud will collect between the Radiator and AC Condesor. Take the top plate off the core suport that ratains the radiator. Pretty good gap there and you can lean the radiator back and see what;s back there and flush it out with a garden hose. At speed their should be enough air moving through the radiator that the Fan should not be a problem. Bad fan clutch is a problem at idle and low speeds.
    If that looks good then put a new thermostat in it. You truck calls for a 195. That dean't fix it then it's time to get the radiator to a shop and have them service it. If you pull the radiator then replace the hoses and the works. one thing to watch out for is the lower radiator hose. It should have a spring in it to keep it from colapsing at High RPM's Cheap hoses from places like Autozone do not come with that spring. NAPA hoses will or you can transfer it from the old hose. When you put new coolant in do a 50/50 mix. DO NOT USE TAP WATER. go to the grocery store and buy DISTILLED water not mineral. Distilled is pur water with minimal minerals and chemicals in it. Garbage in the water you use can cause the coolant to fail early as well as cause corrosion in the cooling system. Before you refill the system look on both sides of the block just above the oil pan in the middle you will find drain plugs for the cooling system. Pull them and drain the block. if you pull them and it doesn't pour out then you have a bunch of sedimate in the cooling system and it may be contributing to your cooling problem. Try flushing it out or go by a Radiator shop and see if they offer block flush services.
     

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