Car runs hot until I put it in neutral and run rpms a lil higher?

It runs hot but I can drop the temp 20+ degrees just by increasing the rpms a bit! Is that definitely the water pump?


And I feel the heater get hotter when pushing rpms higher

Update 2:

Yes coolant is completely full

11 Answers

  • 1 month ago

    Sounds like loose belt. bad pump. maybe bubble in coolant. Maybe all 3.

    Start  by squeezing rad. hose that goes to thermostat. Thermo should be free--Is It? If not , that is probably it.

    Keep milking that cow , then stop and remove rad cap Or check the reservoir (whatever U have). Is it low, Now? refill. Many cars need the block/head bleeds open, some are even  in a steel line connecting two flex rad hoses together. Just pouring coolant in until it looks full, cold, isn't always right. A bubble can still fool you after it's been warmed up.  Get The Book.

    Check tension  on belt.  Should not squeal. Deflect 1/2" at center.

    If U have an electric fan. should come on about 1/2-3/4 heat on gauge and Stay On until it cools a bit, 

  • 1 month ago

    Sounds like the thermostat not opening and closing not allowing water time enough to cool you put it in neutral takes load off

  • Anonymous
    1 month ago

    Then stop tail gating so that you get fresh air in through the radiator.  Or your radiator fan which is an electrical motor blew its fuse or is not working so see a mechanic so he can check it out.

  • M.
    Lv 7
    1 month ago

    Do you have an ELECTRIC radiator fan or a BELT DRIVEN radiator fan? 

    You said something odd: 

    1. "I can drop the temp 20+ degrees just by increasing the rpms a bit" 


    2. "I feel the heater get hotter when pushing rpms higher" 

    Are you getting the idea of overheating by watching a coolant temperature gauge? 

    Or are you getting the idea of overheating by feeling heater air? 

    The engine coolant temperature is meant to be controlled by the thermostat.  Is yours stuck? 

    Which vehicle do you have?? 

    What does your odometer say? 

    -Engine overhaul mechanic and general automotive mechanic since 1972

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  • 1 month ago

    Have you even taken the radiator cap off yet to see if the radiator is full of coolant? If not quit trying to diagnose things because you're going to ruin your head gaskets before you figure it out. A bad thermostat or plugged up radiator is possible.

  • 1 month ago

    When you increase the revs you increase the speed of the water pump, hence better coolant circulation. It may or may not be a problem with the pump. Certainly check the drive belt.

    However, is this the one where you put some sort of sealant in to deal with a head gasket problem?  Then you've very likely clogged the radiator.  These sealants aren't a permanent repair, they're only to get you home, and can cause no end of problems if the issue isn't dealt with properly. 

  • 1 month ago

    By increasing the engine speed you are moving the coolant faster hence lower temperature. 1: cooling fan not working. 2: radiator clogged. Water pump impeller failures are rare but do happen, but the pump is obviously working (speed increase).

    Check that the fan is running (FWD cars) if yes flush the system I guessing that you'll get some chocolate milk color coming out.

  • Anonymous
    1 month ago

    Year make and model.  Check drive belt.  Check for a clogged radiator,  Check fan clutch.  Check water pump.

  • 1 month ago

    First thing to replace is the thermostat. Most are easy to get to and not expensive. When they fail, they can restrict the flow at low rpm. Good luck.

  • 1 month ago

    Check that the radiator fans come on when they should. When the engine is cold, make sure the radiator is full..

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