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ok, WTF, Motor gets hot when heater hoses are connected to the heater core!

Discussion in 'The Garage' started by rjfguitar, Dec 9, 2003.

  1. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I have been trying to figure this out for a month now! I connected my heater hoses together last spring because I had my A/C fixed and it was making the air warmer. Connected the hoses back at the firewall to the heatercore and the gauge heads strait for the red when I start it up. I have changed the stat, flushed the core(doesn't seem to be plugged) and made sure it was full of coolant after it filled the core. Now the heater core is leaking at the connection point from taking the hose on and off, would this cause it to make it overheat?
    As soon as I shut it off and start it back up again it will read 170 degree when it said 220 before I shut it off, could I be getting air in the system some how? Me and everyone I know are stumped! /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/1zhelp.gif
     
  2. Blazer1970

    Blazer1970 1/2 ton status

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    You are definitely getting air into the system. It forms a bubble by the temp sender in the head, and makes it read hot. How long have you run it with the heater core hooked up to let it work the air out? Sometimes you have to change out the water pump to get enough flow to flush the air out of the system. It is easy to tell if the engine is really getting hot. At 195 degrees or below, you should be able to hold your hand on the upper radiator hose for at least a few seconds. If it really gets hot you won't even think about holding your hand on there.
     
  3. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    hmm, I have ran it quite a bit with it hooked up, even drove it down the street a few times but it still does it.
    Remove the water pump? /forums/images/graemlins/thinking.gif
     
  4. equalizer

    equalizer Registered Member

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    "Sometimes you have to change out the water pump to get enough flow to flush the air out of the system."

    I agree with Blazer1970, i had a very similar problem, the heater gauge would go off the chart after a few minutes.Changing the water pump should fix this, especially if you have already addressed the stat..My advice, fix the water pump, its realtively easy and not overly expensive. Also, are you getting a squealing sound (would indicate that you pump is beginning to crap out)
    Hope that helps
    MarcD
     
  5. Confedneck

    Confedneck 3/4 ton status

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    pull the w/p belt and see if there is any play in the bearings of the waterpump..if there is, replace it, if you cant feel any, pull the pump and check the integrity of the fins on the impeller..
     
  6. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I better add I have a high performance summit water pump that I put on my 406 when I swapped motors 5,000 miles ago. /forums/images/graemlins/confused.gif
     
  7. MTBLAZER89

    MTBLAZER89 3/4 ton status GMOTM Winner

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    Maybe try and oull the output hose of the core and make sure coolant is flowing through it could be pluged up or something /forums/images/graemlins/confused.gif Just an idea /forums/images/graemlins/grin.gif
     
  8. 75-K5

    75-K5 3/4 ton status

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    Open the rad cap and let the engine warm up until the stat opens. Stick a meat thermometer in the radiator and let it sit there for 5 minutes or so. I replaced the thermostat in my c10 and the temp gauge kept redlining, so i manually checked the temp in this manner and found it to be right at 195. If you know it's not overheating, I wouldn't worry too much about it. I don't think it's drastic enough to change out a new water pump.
     
  9. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    Where are your heater hoses connected?
     
  10. 99firehawk

    99firehawk 1/2 ton status

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    If you leave the heat off does it still get too hot? Try hooking them up and leaving your vent in the cold position and and in the off position, Does it still get hot? Yes Im going somewhere with this just let me know the results before I go any further
     
  11. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    Maybe try and oull the output hose of the core and make sure coolant is flowing through it could be pluged up or something /forums/images/graemlins/confused.gif Just an idea /forums/images/graemlins/grin.gif

    [/ QUOTE ]
    Made sure the water neck and hose was clean, it is and even pulled the hose off to make sure I was getting return. It doesn't flow heavy but flows back to the radiator about the speed of a garden hose on slow. Is this normal or am I supposed to have decent pressure coming back to the rad. Could something be plugged inside the intake and it's using the heater hoses as the primary return? Wait that can't be it really either because water still flows and returns from the heater core. /forums/images/graemlins/frown.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
     
  12. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    [ QUOTE ]
    Where are your heater hoses connected?

    [/ QUOTE ]
    I used a little double sided nipple deal and I just have the hoses plumbed together.

    It doesn't matter if the heater is on or not, if the hoses are connected to the heater core the guage shoots up. It has to be air or something.
    I can tell the water isn't really hot in the radiator but what I fear is that it isn't getting proper flow through the motor and the water is hot in the motor and cool in the radiator and I am chicken to let it just run because I don't want to ruin my brand new 406. /forums/images/graemlins/confused.gif
     
  13. 87BrnRsd

    87BrnRsd 1/2 ton status

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    old trick that i have found works is to drill a tiny hole in the flanged part of the thermostat. This will allow air by and should fix the problem if it is truly air in the line.
    -Just my two cents

    -Harrison
     
  14. Rob 85K5

    Rob 85K5 1/2 ton status GMOTM Winner

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    try swappiing the hoses at the heater core, so the fill is from the bottom, and the air can move out of the top. I can't remember which is the fill, water pump I am assuming.
     
  15. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    [ QUOTE ]
    try swappiing the hoses at the heater core, so the fill is from the bottom, and the air can move out of the top. I can't remember which is the fill, water pump I am assuming.

    [/ QUOTE ]

    NO!!!!!!

    The water pump is a return! So is the radiator. That's why I asked where he had the hoses connected but he didn't understand my question. Hopefully he'll update us on this issue.

    The hot coolant comes from the top of the engine (intake manifold) and either returns to the water pump or the radiator. Mine goes to the radiator.
     
  16. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    I have one hose coming from the intake(engine Return) and one from the radiator. What are you thinking Tim?
     
  17. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    [ QUOTE ]
    I have one hose coming from the intake(engine Return) and one from the radiator. What are you thinking Tim?

    [/ QUOTE ]

    Yours are hooked up correctly then.

    I was thinking you had one hooked to the water pump and another to the radiator which would effectively make a big air pocket. Yours are hooked up right though, so that idea is out.
     
  18. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    [ QUOTE ]
    I have one hose coming from the intake(engine Return) and one from the radiator. What are you thinking Tim?

    [/ QUOTE ]

    Yours are hooked up correctly then.

    I was thinking you had one hooked to the water pump and another to the radiator which would effectively make a big air pocket. Yours are hooked up right though, so that idea is out.
     
  19. 99firehawk

    99firehawk 1/2 ton status

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    Find a shop, or someone with one of these
    http://www.johnsonmfg.com/temp/j360cs.htm

    they are the cats a$$ for bleeding cooling systems, Buy it your self best 60$ i ever spent.
     
  20. Rob 85K5

    Rob 85K5 1/2 ton status GMOTM Winner

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    Re: ok, WTF, Motor gets hot when heater hoses are connected to the heater c

    he could still be trapping air if the fill hose is not on the bottom!
     

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