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Are serpentine belt water pumps "reverse rotation"?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by MOABDADC22, Oct 7, 2001.

  1. MOABDADC22

    MOABDADC22 1/2 ton status

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    Are serpentine belt water pumps \"reverse rotation\"?

    My water pump took a crap and I replaced it. The new pump says that it is a reverse rotation pump. Is this true? I ask this because since changing the pump, the temp gauge has not gone above 100 degrees. The sending unit is good and the wire is hooked up. The "hot" air coming out of the heater vent is warm at best and there is enough anti-freeze in the radiator. Could the thermostat be stuck open??

    <a target="_blank" href=http://www.moabdadc22.alloffroad.com/>http://www.moabdadc22.alloffroad.com/</a>Real four wheelers don't need tools to remove body panels, paint, tail lights..etc.
     
  2. Twiz

    Twiz 1/2 ton status

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    Re: Are serpentine belt water pumps

    The serp driven pumps are reverse rotation, but not reverse flow.

    As far as not getting up to temp. Remove the radiator cap and start the engine cold- Is it flowing right off the bat? (keep in mind that the heater core might be plumbed into the radiator and flows to it cold). Reinstall the cap and let the engine idle normaly, check the upper hose, it should eventualy get hot "all of a sudden" not gradualy get warmer and warmer. And finaly, pull the t-stat houseing and check it out.
    T-stat and gaskets are cheep, and easy to replce. It might be better just to replace it.

    If this problem happend right after the water pump was replced, than that would be the first thing to suspect as being the problem.

    Is all the air out of sys. Afew months ago, someone on this board, had a overheating problem. It turned out to be a air pocket right at the t-stat, so the t-stat wouldn't open and there was no coolent flow to the radiator.


    <font color=blue>Twiztid</font color=blue>
     
  3. DesertDueler

    DesertDueler 1/2 ton status

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    Re: Are serpentine belt water pumps

    It is a very good possibilty that you have a big air pocket. The reason I say this is because you say the heater doesnt blow hot air and the gauge doesnt go up. If there is an air pocket by the sending unit the sending unit wont register the temp. The sending unit has to be in the coolant in order to work. We just had the same thing happen at work yesterday on a ford windstar. It wouldnt blow hot air out of the vents and we couldnt get the air pocket out so the motor was running exremly hot but the temp gauge was showing it was running really cold. Best way to tell is run it for a couple of minutes and touch the radiator hoses and of they are cold but the motor is hot then you have an air pocket and if you have an air pocket the thermostat wont open.

    86Jimmy 4"&35"MTRs,87 burb 4"&35"MT,69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Are serpentine belt water pumps \"reverse rotation\"?

    Not hard to check. No heat, no pressure. Pop the cap after its been running, and if you are adventurous, stick the tip of your finger in the fluid. If not, use a meat-type thermometer to check it.

    FWIW, my car never went above 100 when I bought it, turned out PO had removed the t-stat. One stuck open (I beleive that is how they are intended to fail, wide open) could probably do the same. Check the fluid tempreature/pressure, easy enough to do, and its free.

    Dorian
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  5. Pure Insanity

    Pure Insanity 1/2 ton status

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    Re: Are serpentine belt water pumps

    Twiz is right as usual, reverse rotation, not reverse flow. But to add to it, a pump will reverse flow if spun in the wrong direction. Its a direct drive to the impeller. The shaft may spin the opposite direction, but the impeller and cavities are designed to do so. A reverse rotation needs to be spun "backwards" or it will not flow as well. If you have a standard flow that you took off and replaced it w/ a reverse flow, or vice versa, it will not flow enuff. The impeller is designed to "scoop" the coolant and push it along. If its spinning bass ackwards, it will still flow, just not as hard, or fast.

    Did I explain that right or did I mess it all up?!?! I know what Im trying to say, and I think I got it right but Im not sure if it came across right!

    Now, if memory serves me right, some of the newer GMs DO send the coolant the "wrong" direction. I might be wrong about that tho.

    If ya can't stop.......Smile as you go under! [​IMG]
     
  6. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: Are serpentine belt water pumps

    Only LT1 engines are reverse flow coolant as far as I know.

    I am suspecting a big air pocket too, but I think you're trusting your electric gauge too much. I'd never trust any gauge that was electric. I suggest in the future that you get mechanical gauges.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  7. Pure Insanity

    Pure Insanity 1/2 ton status

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    Re: Are serpentine belt water pumps

    I thot there was a motor that was reverse flow, but I wasnt sure. Now that you mention the LT1 I remembered it.

    If ya can't stop.......Smile as you go under! [​IMG]
     
  8. Twiz

    Twiz 1/2 ton status

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    Re: Are serpentine belt water pumps

    Pureinsanitys right. [​IMG]

    Just to add to it some. I like to drill a very small hole in the T-stat body. This will help purge the coolling sys and get all the air out of 'em. (exp. If the coolant was draind below the thermostat level) Also, in some of the colder climates, this will also keep the frost off the radiator by keeping some heated coolent flowing threw the radiator.

    On the down side, the small hole would also "lower" the T-stat opening temp, and increase warm-up time. But, I think the plus side out weighs the minor side-efects.

    <font color=blue>Twiztid</font color=blue>
     
  9. Pure Insanity

    Pure Insanity 1/2 ton status

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    Re: Are serpentine belt water pumps

    Yet another thing to do, which I am sure a bunch will disagree w/, is to gut the T-stat. All it is then is a restrister plate. It still slows the flow as it does w/ the guts in but will never stick, and doesnt cause air pockets. It may warm up slower tho. Living in Fla, I have never seen any adverse effects to the slower warm up.

    If ya can't stop.......Smile as you go under! [​IMG]
     

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