2000 for ranger 3.0L temp problems?

When I first start it, it warms up fine and heater functions normally, however, after some driving, the temp guage drops all the way to C and the heater goes out at this point, then the guage pegs out at hot breifly, then falls back to normal 195 degrees. Heater stops working completley at this point. It has a new water pump and thermostat and coolant levels are ok at all times. Any ideas? Maybe a clogged radiator?

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  • 1 month ago
    Favorite Answer

    Take the radiator cap off and run the motor for 15 minutes. Watch for air bubbles coming out of the radiator neck. You have an air pocket causing that problem. If the bubbles never stop have a block test done to find out if there is exhaust gases in the cooling system due to a bad had gasket.

    Source(s): Mitsubishi Master Tech
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  • zipper
    Lv 6
    1 month ago

    Clogged radiator or heater core. I saw this once and when I removed the line to the heater core their was a shop rag in the line. Once removed it worked fine after that. Good luck, Their could also be a blockage in the block causing this issue.

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  • Anonymous
    1 month ago

    Was there a reason you replaced the engine thermostat & WP? Or was it overheating?

    What you have described sounds like the cooling system has a pressurization leak. My suspicion is that you have a slow coolant leak near the top of the radiator and the level slowly drops a bit over time causing a bubble in the heater core. If the engine upper radiator hose gets hot but not pressurized hard, I would check the radiator plastic side tank seals because your cooling system is not holding pressure. This is often near the top of the radiator. For instance, if your coolant is always 3-4 inches low, look 3-4 inches down on the plastic radiator side tank seals for coolant leak residue. Loaning out a cooling system pressure tester from the local parts store would have discovered a pressure leak like this and saved you the cost of the water pump and thermostat parts with labor.

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  • M.
    Lv 7
    1 month ago

    It sounds like your coolant level (in the engine and active cooling system) is significantly LOW.

    Remove the radiator cap and look into the radiator when the engine is COLD.

    The coolant should be right up to the bottom of the radiator cap. If it's not, fill it!

    Make sure your coolant reservoir is filled to the COLD line.

    If your radiator is low but your coolant reservoir is filled, you may have a plugged or kinked hose (between the coolant reservoir and the radiator neck), or your radiator cap may not be working properly.

    If coolant is disappearing from your cooling system, you probably have a leak somewhere.  You could have a leaking cylinder head gasket.

    Most people do not understand how the modern cooling system works, or that driving with low coolant can cause expensive damage, even driving a short time.

    If the coolant temperature of an aluminum head engine gets high, you should pull off the road immediately and shut the engine off, and not start it again unless you found the problem and dealt with it somehow.

    MY Ford Ranger has the coolant temperature gauge SENSOR in a heater hose, away from the engine.  If coolant is low and stops circulating, the gauge reading will drop, even though the engine begins to overheat.

    -Engine overhaul mechanic and general automotive mechanic since 1972

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  • Dan
    Lv 4
    1 month ago

    You have an air lock. Park the truck on a steep hill, facing up the hill. When it's cold remove the radiator cap, not the reservoir cap. Start it up and let it run for ten minutes with the rad cap off as you top it up running, then replace the cap and try it.

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  • 1 month ago

    Check coolant level.  When its very low on cool the temperature gauge won't read correctly.

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  • Anonymous
    1 month ago

    Get a bleeder funnel kit and bleed the coolant.  Make sure the heater is ON when bleeding.  Good luck.

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