Thread: Heat goes UP then down then up

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  1. #1 Heat goes UP then down then up 
    GTP Level Member chevyy1212's Avatar
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    Ok 07 GT it's my mommys... The heat takes forever to get up to temp then fluctuates from operating temp down to 140-150ish so the heat never stays at a good temp. I've changed the Tstat and the only thing I can think of is air left in the system? Any special way to bleed these I thought there was been years since I had my GS.
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  2. #2 Re: Heat goes UP then down then up 
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
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    I'd backflush the heater core while your at it too.

    Then remove the thermostat, refill the LIM with coolant to get the level all the way up, re-install and top off the radiator. Run the car with the rad cap off and allow it to warm up, add coolant as needed. You shouldnt have to bleed through the T-stat housing doing it this way.

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  3. #3 Re: Heat goes UP then down then up 
    GTP Level Member chevyy1212's Avatar
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    Quote Originally Posted by Fivefingerdeathpunch View Post
    I'd backflush the heater core while your at it too.

    Then remove the thermostat, refill the LIM with coolant to get the level all the way up, re-install and top off the radiator. Run the car with the rad cap off and allow it to warm up, add coolant as needed. You shouldnt have to bleed through the T-stat housing doing it this way.
    I like this plan. Is it just me but I remember these cars being a pain to get the air out of the system?
    1998 GS with Open cone, PLOG, ZZP Catless DP, tune & Intense MPS 3.6. Pulls good enough to make the woman smack me and call me a D!*k.
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  4. #4 Re: Heat goes UP then down then up 
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
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    I just think some people have bad luck???

    I've never ran into a issue with one yet, worked on dozens of 3800's and never had a issue yet. Sure some take longer but knowing a few tricks of the trade help. Squeezing hoses, revving the motor, quick shuts offs to burp it and so on.

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  5. #5 Re: Heat goes UP then down then up 
    Killa Bee Scottydoggs's Avatar
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    ive yet to have air bound core but it sure does seem to happen to a lot of cars here.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, gen 5 N* 3.0 pulley, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW
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  6. #6 Re: Heat goes UP then down then up 
    GTP Level Member chevyy1212's Avatar
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    Quote Originally Posted by ScottyDoggs View Post
    ive yet to have air bound core but it sure does seem to happen to a lot of cars here.
    Yea she got screwed out of 3 flushes at a shop a few years back after I took it flushed the heater core and bleed it off a few times been good for years now it's doing it again after the resivour hose got ate up buy the belt. Very few things can cause this tho. I jacked up the front end for kicks while bleeding too.
    1998 GS with Open cone, PLOG, ZZP Catless DP, tune & Intense MPS 3.6. Pulls good enough to make the woman smack me and call me a D!*k.
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  7. #7 Re: Heat goes UP then down then up 
    Killa Bee Scottydoggs's Avatar
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    bleeding the t stat wont fix air in the heater core. the core needs to be filled up. take both hoses off the alt bracket, and flush one with a garden hose, then flush the other one, then put the hoses back on with them as full of water as possible.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, gen 5 N* 3.0 pulley, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW
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  8. #8 Re: Heat goes UP then down then up 
    GTP Level Member chevyy1212's Avatar
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    Quote Originally Posted by ScottyDoggs View Post
    ive yet to have air bound core but it sure does seem to happen to a lot of cars here.
    Yea she got screwed out of 3 flushes at a shop a few years back after I took it flushed the heater core and bleed it off a few times been good for years now it's doing it again after the resivour hose got ate up buy the belt. Very few things can cause this tho. I jacked up the front end for kicks while bleeding too.
    1998 GS with Open cone, PLOG, ZZP Catless DP, tune & Intense MPS 3.6. Pulls good enough to make the woman smack me and call me a D!*k.
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