2000 Navigator Overheating

Lincoln Navigator / Lincoln Aviator

  1. jbelcourt

    jbelcourt Dedicated LVC Member

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    I'm having an issue with my Navigator I'm hoping you guys can help me with. I just bought it like a month ago so I don't know a ton about it.

    It had a small leak by the upper hose, which I thought was a clamp so I replaced it. It still leaked so I was thinking it was a small hole in the radiator or the plastic side of the radiator. Not wanting to drop money in this thing, I threw a bottle of K-Seal stop leak in there. It stopped leaking. Four days later, I'm driving and my temp gauge pegged. My scanner showed it was at 240° so I got off the interstate and shut it off. Eventually opened the tank and it started boiling and sucked it dry into the block. Bought 2-gallons, first gallon immediately sucked into the block from the tank, second one did the same after squeezing the hoses with coolant in the tank.

    Bought a new cap, made sure it was full and pumped the hose. Kept an eye on it all week, via my scanner and it was perfect. Still no leaks either.

    Today, I happened to check my scanner while driving and it's at 220°. Got to 225° and while I was backing into a parking spot, it hit 235° and dummy gauge started climbing. Shut it down, let it cool a few hours and checked. Tank is still full, upper and lower hoses were equal temps (to the touch at least) squeezing the hoses blows into the tank so it's not clogged that I can tell.

    I have no clue what to do next or what it could be. Any suggestions?
     
  2. Ezjpimp

    Ezjpimp LVC Member

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    I would say your thermostat is sticking if the tank is still full. As cheap as a new one is ($10) and how easy it is to replace it, I would start there. Both my Navi's running about 180-200 tops all year round.

    This is from the service manual.
    1. Disconnect the upper radiator hose, the heater water inlet hose and the heated PCV inlet hose from the water outlet adapter.
    11.png

    2. Remove the water hose connection (8592).
    22.png
     
    Last edited: Nov 6, 2017
  3. jbelcourt

    jbelcourt Dedicated LVC Member

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    Yeah, I suspected a possible blockage.

    Just an update on this. When I drove home last night, it was normal temp (195) but I pulled the cap off anyways to see if there was air trapped. Before pulling the cap off, the upper hose going into the thermostat was really hard. I pulled the cap, it burped a puddle of coolant out then stopped. The coolant in the bottle was warm. Not even remotely hot, I could touch it and it felt barely warm. Also, the upper hose was then "squeazable" and much less stiff. The temp dropped really quickly down to 177.

    I just got off work, it got up to 195 again. When I got home, I pulled the cap again. It starts to bubble really hard when I start opening the cap and there is a vacuum to it, which I can feel in the cap when trying to lift it, and then after a few seconds I can take off the cap, it stops bubbling and it settles. The temp drops almost instantly after pulling the cap.

    Sound like I have bad circulation?
     
    Last edited: Nov 6, 2017

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