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  1. #1
    Join Date
    Mar 2012
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    5.7 Hemi Overheating After Thermostat Replacement

    Hey Guys,

    I've been reading this forum for a while, and haven't had a problem finding solutions to my problems until now.

    The Basics: 2005 Magnum RT, 138K Miles, bone stock, recently replaced throttle body and thermostat, still need to replace crank sensor and fix front suspension problems. Owned since 2006 with 13K miles.

    I had problems with the thermostat sticking a while ago and the engine not heating up. Seemed to clear itself, so I didn't worry about it until I was going in to replace the throttle body. After completing those installs (stock mopar parts), the engine now overheats(temp gauge will max out if I don't shut it down, even idling). I've bled the system multiple times, and checked to make sure that the wiggle valve on the thermostat was up. Still overheats, but more slowly. The fans do turn on. I did notice the rubber membrane on the new t-stat, so I just checked the old one. The membrane is completely gone on the side that faces out, and half gone on the inside.

    Where do the pieces of membrane end up going, and it is possible that a piece is partially blocking coolant flow? Or have I just not gotten all of the air out of the system? When I bled it this evening, the coolant came right out of the bleed plug with no bubbles.

    This has been going on since last Sunday, I can't keep driving my wife's car forever.

    Any thoughts?



  2. #2
    Join Date
    Sep 2005
    Location
    Lorain Oh
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    34,262
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    you haven't gotten all the air out. And if you keep letting the car get that hot I promise you a motor will be next from a dropped valve seat.
    BFNY Performance
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  3. #3
    Join Date
    Feb 2012
    Location
    Central Ky
    Posts
    129
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    Just swapped my tstat yesterday. Was no membrane on the outside fwiw. Just on the inside/ spring side. Mines in good shape. You could drill a 1/8" hole in it (flat area close to the ridge and keep it away from the braces on the stat that hold the center). That will ensure the air escapes. Mine functions well like this. It's something I picked up years ago. Radiator fins blocked/plugged? Try a cooling system flush? Overflow tank look clean inside?

    Just some areas to look at.

  4. #4
    Join Date
    Aug 2004
    Location
    Ocala, Florida :-)
    Posts
    11,009
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    The 5.7 motors don't come with a bleeder valve, have you installed one???

    Remove the plug in the water pump housing and install a bleeder valve, I got my parts from Advance Auto Parts.

    Here is what they look like.

    Bob

    PLUG:


    Adaptor:


    Bleeder Valve:


    Installed:



    Old plug removed:
    Bob in Ocala, Florida, 05' Magnum RT, 74 years young - married 53 years. Superchips tuner & Flowmaster 40's. 402 Motoring rear spoiler, mud flaps, tinted & painted tail lights. Danko shaker hood, 69' Charger grille, front spoiler, rear diffuser.

  5. #5
    Join Date
    Mar 2012
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    Thanks for the responses.

    Bob, I did mean that I had opened the plug, I hadn't thought of a bleeder valve as shown above. I may need to consider that.

    IntenseRT, I don't really want to pull the tstat back out to drill it, don't want to damage the gasket and deal with that.

    Hemi31, thanks for the advice about the valve seat. Definately don't want that to happen. The temp gauge only got above 3/4 a total of 3 times. Once on the way home, and twice while trying to bleed the system. Hopefully no damage done.

    I decided that I'm going to take it in to the mechanic. I can't get to the crankshaft sensor without having it on a lift and/or dropping the starter. I wrench on my cars for fun, these few things are not fun for me, so I'll just have someone else do them. I'll have the cooling system flushed while it's there, the coolant is original, so it's time to change it anyway. I'll let the mechanic deal with bleeding the system.
    Last edited by Green05Hemi; 03-25-2012 at 04:27 PM.

  6. #6
    Join Date
    Feb 2012
    Location
    Central Ky
    Posts
    129
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    Sounds like the right way to go. To clarify on the hole, besides helping air escape more quickly past it I don't want a CEL but wanted the car to warm up a hair slower also because I like to drag race here and there.

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