Slow heat creep

Lincoln LS

  1. Eric Cooke

    Eric Cooke LVC Member

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    OK, I have researched this and I am still stumped.

    I have a 2001 LS V8 and I am getting a slow heat creep. The car will drive fine and the temperature will rise accordingly and then stabilize at normal operating temp. After about 20-30 minutes the temp will begin to rise to about the 2/3rd mark but not above.

    I replaced the thermostat about 2 months ago and replaced the hydraulic fan with a 3200 CFM electric with a shroud at the same time. The degas bottle releases pressure when I open it and I have purged the system several times to make sure it is not an air bubble. The outside temp is 75 degrees and I am not running the A/C. Turning on the heat to 90 degrees does not make a difference.

    My upper radiator hose blew a little over a week ago. I replaced it and did all the bleeding, etc. and all was fine for 4 days before the heat creep started.

    Any advice would be appreciated. I am wondering if the water pump is beginning to go.
     
  2. joegr

    joegr Dedicated LVC Member

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    You have a leak (probably tiny) somewhere in the cooling system that is letting air in each time the engine cools off.
     
  3. Eric Cooke

    Eric Cooke LVC Member

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    So, even though the degas releases pressure when I open it? I am not saying your wrong (you have helped me several times already), I am just confirming.
     
  4. Eric Cooke

    Eric Cooke LVC Member

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    Also- checked both the upper and lower hoses to make sure they were (at least by feel) the same temp. I was told this helps to diagnose that the water pump is working.
     
  5. joegr

    joegr Dedicated LVC Member

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    Yes, even with the system pressurizing, you can have a leak. I've even had one (chased it for over a week) that wouldn't show up during a pressure test (hot and cold). Apparently, it would only leak under the exact right circumstances and was sealed otherwise.

    Of course, there could be other possibilities, but this is the most likely/frequent one.
     
  6. Eric Cooke

    Eric Cooke LVC Member

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    OK, here is a thought. If I start with the degas cap-I am thinking putting Vaseline on the thread to see if the seal improves-and then work backward from there? Do you think this is the way to go?
     
  7. joegr

    joegr Dedicated LVC Member

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    Actually, when the thermostat is open (engine running) one should be noticeably cooler than the other (although this operating point can be hard to catch). If both are always the same, it indicates a coolant flow problem. Causes could be: trapped air (leak), stuck thermostat, bad water pump, clogged radiator (coolant flow or air flow), bad fan, ...
     
  8. Eric Cooke

    Eric Cooke LVC Member

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    If there is a coolant flow problem when you open the release valve (by the degas bottle) would the coolant still come out under pressure?
     
  9. joegr

    joegr Dedicated LVC Member

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    It's certainly something to try. I've noticed that they sometimes don't seal very well until left undisturbed for a few days. I have used Vaseline on the degas cap seal before to improve the seal (I had to do it when I was pressure testing). Dielectric grease can be used too.
     
  10. LS4me

    LS4me Dedicated LVC Member

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    My upper radiator hose did the same. I had the hood open for some reason while on vacation. I saw the whitish residue on the right shock tower, hood insulation and other various places. I suspected a leak but couldn't find one and the coolant level looked normal. I drove home the ~1500 miles with no problems. A couple of weeks later the upper hose finally sprung the leak permanently! The temp never rose above 1/2, which is why the residue confused me.
     
  11. joegr

    joegr Dedicated LVC Member

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    Yes. The coolant being heated by the engine causes the pressure, not flow.
     
  12. Eric Cooke

    Eric Cooke LVC Member

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    So- if the Vaseline trick doesn't show an improvement I am going to guess that the water pump is my next culprit. Do you agree?
     
  13. Eric Cooke

    Eric Cooke LVC Member

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    To add another variable. I don't think that the heat is blowing as hot as it should. Does that add the DCCV into the mix?
     
  14. joegr

    joegr Dedicated LVC Member

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    I still think that it all still points to a small leak letting air in.
     
  15. Eric Cooke

    Eric Cooke LVC Member

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    I will start with the least expensive options first (obviously) and go from there. Can you give me any tips on checking the water pump?
     
  16. joegr

    joegr Dedicated LVC Member

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    There's not much to it. Remove it and look at the vanes. See if any are eroded away or if the impeller is loose on the shaft. Look for signs of coolant or coolant residue (usually a white film) anywhere to indicate leaking. I'd get a new gasket for it, but you can reuse the old one. Just put a little gasket maker on it.
     
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    • Eric Cooke

      Eric Cooke LVC Member

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      Thank you. I will check it out.
       
    • Eric Cooke

      Eric Cooke LVC Member

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      Update: I tried putting a little vaseline around the cap to see if that was where the leak was and drove the car approx. 8 miles in stop and go traffic. The car completely overheated to the point of releasing steam and fluid from around the coolant tank cap and the warning light coming on. Turning the heater to 90 degrees and full did not have any effect on the temp and the air was not hot. This is leading me to believe it is the water pump and I am going to pull it to verify but any input would be greatly appreciated.

      Another interesting thing is that the car can idle for any amount of time and it does not overheat. ONly driving it makes it overheat. I have checked the radiator for blockage (plastic bags, etc.) and found none.
       
    • joegr

      joegr Dedicated LVC Member

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      Well, it could be the water pump, but I see nothing to suggest that it is. I still say that coolant flow is being blocked by trapped air caused by leak(s). This is the far, far more common problem. There really isn't much that can fail on the water pump.
       
    • Eric Cooke

      Eric Cooke LVC Member

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      Huh. Any recommendations on getting the trapped air out beyond the steps listed in the tech article here? I have run through all of those steps several times and if I have air trapped, then I am guessing it is in the heater core since it is not blowing hot, and I am not making progress.
       
    • joegr

      joegr Dedicated LVC Member

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      You have to follow the procedure exactly (as in to the letter). However, it won't help much until you find the source of the leak.
      It seems that you are unlikely to find the source, and it doesn't matter anyway. Experience says that all the plastic parts need to be replaced when one starts to fail.


      Usually, the radiator is okay and doesn't have to be replaced. On your gen I V8, you need to replace the degas bottle (use Motorcraft only, cap is probably okay), the thermostat housing and engine fill cap (best to use the Jaguar metal parts, then you won't have to do this again), the cross over hose assembly, the upper radiator hose, and the lower radiator hose.
       
    • Eric Cooke

      Eric Cooke LVC Member

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      Do you recommend Rock Auto to get the parts? Also- just to make sure I order correctly- I order the housing for a 2001 Jag S-Type 4.0, right?
       
    • Eric Cooke

      Eric Cooke LVC Member

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      Thanks again for your help. I am ordering the parts today.
       
    • Eric Cooke

      Eric Cooke LVC Member

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      The one part I want to make sure I have correct is the crossover hose assembly. When I search for it I get a 3 pack of gaskets for the thermostat. It reads like this on Rock Auto-
      Cooling System : Coolant Water Crossover Mounting Set
      VICTOR REINZ Part # GS33515 Material: Victo-Tech
      Is this correct?
       

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