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Blazer Engine Temperature Questions



  • hoses look old
  • jlflemmonsjlflemmons Posts: 2,240
    Does it overheat going down the road faster than 35mph? Fan clutch only effective at lower speeds.
  • yes it over heats at faster speeds
  • jlflemmonsjlflemmons Posts: 2,240
    Well, that does sound like a radiator. If it only overheated below about 25-30, I would say fan clutch. But the fan clutch disengages around 25 as the air coming in the grill is moving faster than that.

    Looks like it's time to pull the radiator and compare the cost of a new one to having that one flushed and rodded by a radiator shop.
  • I have to turn heat on to maintain around 210
  • why the radiator its new only 5 months old
  • jlflemmonsjlflemmons Posts: 2,240
    It may be only 5 months old, but it is the only thing there that could cause that problem, unless you have a hose collapsing while running (not likely).

    If it were the fan clutch, it wouldn't overheat at highway speeds.
    If it were the thermostat, it would heat up quickly, and all the way to the max.
    Water pumps don't fail in this manner, they leak out the shaft when the seal lets go, or start wobbling and leaking at the same time. You would be losing coolant.
    In a Blazer, water is always moving through the heater core. Unlike a lot of cars, there is no heater control valve to turn the water flow off and on. There are damper doors that either bring in cool air or hot air, depending on where you set the controls.

    Now, what may have happened is that coolant sludge has formed in the engine, and all the cooling system work has knocked it loose and it has settled in the radiator. If so, the radiator just needs to be flushed, along with the rest of the cooling system. I don't mean drained and refilled, I mean flushed.

    [edit] Did you have the heater core flushed? These have been known to get clogged and will not allow all the water flow through them. You can sometimes here them gurgle when this happens.

    Which antifreeze was in the vehicle when you started working on this, the green or the orange long life stuff. I am sure someone has told you never to mix the two. They don't play well together and will really clog things up.

    Good luck
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