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Fluctuating Water Temperature

Discussion in 'Under the Hood' started by PHL Flash, January 26, 2005.

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    1. PHL Flash

      PHL Flash New Member

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      Does anyone have an idea for a fluctuating water temperature problem? The water temp gauge operates like a windshild wiper. I started a thread on this a few weeks ago, but I have tried a few new things since. And the problem remains.
      System has been pressure tested, and no leaks detected. No sign of hydrocarbons in the coolant, and no indication of coolant in the exhaust. Thermostat has been replaced, as has the water pump, the temperature sending unit and the radiator. The heater core was replaced last February, and the radiator in April. None of these component changes made a difference. There is no appreciable coolant loss from the recovery tank, and no bubbles detected there.
      My mechanic gave me a copt of TSB 95-18-5 titled 'Temperature Gauge Fluctuations and Inaccurate High Readings'. It said to change the gauge and sending unit. As the sending unit had been replaced with a Ford part, I went for the gauge. Ford wanted $175 for a gauge, a bit pricey. So I got an entire cluster from the junk yard and installed the gauge. The fluctuations continue, but the swing isn't as severe, going from below the 'N' up to the 'M'. Mechanic used a thermal sensor to identify the temperature swing as 180-220. The heat output fluctuates also, indicating the water temp change is accurate. I was going to bypass the heater, but I've got to wait till spring for that project.
      Question is why does the temperature fluctuate? I am told it 'could' be the head gaskets, but I am hesitant to tear down the engine this time of year. If I knew for sure that is was the head gaskets, or the intake gasket, I would plan to change them in the spring. But engine has 145k on it, and it may be wise to rebuild or replace it, instead of just replacing the gaskets. Is there a definitive test, other than disappearing water or a massive leak, to point to the head gaskets? I have toyed with the idea of a replacement engine, rebuilt on the shop floor and just replaced on a weekend. But I would hate to go that route if there is another solution.
      Thanks in advance and any help and expertise will be greatly appreciated.
       
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    3. Eneurb

      Eneurb Active Member

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      I believe that TSB calls for a matched set of guage and sender. The wrecker cluster that you have purchased probably has the same part no. guage in it that you already had.
       
    4. PHL Flash

      PHL Flash New Member

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      Ah, right you are Eneurb. I didnt read it that close. It wants the 'kit' to replace both components. Interesting. However, this TSB concerns 'temperature indications'. I am quite certain the water temperature is really fluctuating, as indicated by both the heat output, and the mechanics thermal sensing. I am not at all convinced of it being only an indication problem, but I am at a loss. Aside from the obvious (thermostat opening) what would cause the temp to fluctuate so noticably? I will check check out the actual kit at the Ford dealer tomorrow, though I may be afraid to find out the cost. Thanks for the tip.
       
    5. Eneurb

      Eneurb Active Member

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      Look into an aftermarket temp. indication setup such as autometer. You could be having head or t-stat problems, and have nothing wrong with you gage.
       
    6. sabatosh

      sabatosh New Member

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      Have you replaced the sensor yet? I'd say it's the sensor or a short/corrosion in the wiring to it. I wouldn't trust your mechanics any of them as far as I could throw them.
       
    7. PHL Flash

      PHL Flash New Member

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      I did replace the sensor, with a Ford part, but it made no difference. The water temp is really fluctuating as the thermostat opens and closes. I can feel the heat output (or lack thereof) with the changes. I personally dont believe it is an indication problem, but I just dont know enough about the internal workings and foibles of this engine. I do trust my mechanic as he is a good friend with many years of experience, though not all on Explorers. He really cant tell me what the problem is either. I thought someone with an Explorer may have had a similar experience. Thanks for the expertise and responses.
       
    8. jnealg

      jnealg Active Member

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      this may sound stupid and I am no mechanic but I have a fairly analytical mind...

      Could you have a bad new thermostat? It seems to me that it should be opening before 200 degrees so maybe it is sticking then "popping open". What happens when you boil it does it open at the right temps?
      Next I'd look at flow, check for restrictions. I've heard bad radiator caps causing fluctuations.
      I wouldnt run long this way but I'd pull the thermo to see if the temp still moves or remains steadily low like it should.
       
    9. PHL Flash

      PHL Flash New Member

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      jnealg -- I have put in three thermostats recently, one from AutoZone and the others from Ford. It makes no difference with this problem. When the indicator reaches about the 'L' on the gauge, the thermostat opens, and in three seconds, the indicator drops like a stone and points down below the 'N'. And the heat output disappears. Then, the thermostat closes, water gets warmer, heat returns and the cycle repeats itself. Usually, my eyes are glued to the gauge, ready to shut down, should that gauge continue to climb past the 'L', and not drop off. As for the cap, it was replaced last month, and made no difference. And, this problem, the temperature indicator swinging like a windshield wiper with water temp fluctuations, has been present for at least 3-4 YEARS in some form. It is only recently that the temp swings were getting more pronounced. The sweeps became very drastic and noticible. After my mechanic checked the system and found no apparent obvious problems or leaks, he suggested changing the water pump. It was the original, so I thought I'd give it a go. The problem persists, however, though not as drastic. The old water pump looked totally normal to my naked eye. I am perplexed, but am hesitant to tear down the motor unless I can nail down the cause. I cant afford the down time right now. Thanks for your observations. I really do appreciate it.
       
    10. gss

      gss Member

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      How is your hoses? Is there any chance one is getting sucked flat and then opens back up at higher temp as the water builds up pressure?
       
    11. jim blair

      jim blair New Member

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      I have a friend who cured this same problem with a new radiator cap. aparently they do go bad even tho i have never had one go bad.
       
    12. sabatosh

      sabatosh New Member

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      Well if you aren't losing any coolant, then the only problem you can possibly have is with circulation or air in the system. My sister was having temperature swings with her car overheating after some tune up maintenance. Apparently they had not tightened the cap good. It's possible that you have some sort of blockage in the engine something broken off in the water jacket that's making it difficult for the water to pressurize, then the pressure gets high and the pump reliefs and then the pressure drops it unclogs and the same cycle over and over.

      It has to be something loose flying around in the water jacket of the engine that's obstructing coolant flow. That's the only thing that really makes sense to me at this point.
       
    13. agzaretzka

      agzaretzka Elite - G-d Bless!

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      I'm curious. Does the water temp stay consistent if you run without the thermostat?
       
    14. PHL Flash

      PHL Flash New Member

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      I did change the cap last month, with no noticable change. Symtoms remained. As for removing the thermostat, the weather has again turned cold in NJ, so that is a project that will have to wait a couple months. Someone suggested changing the clutch fan, that a sticking clutch fan could cause these symtoms. So I am thinking of changing that as it is the original. Thanks for all your ideas.
       
    15. Eneurb

      Eneurb Active Member

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      Be careful if you are going to run without a thermostat. Without the restriction in the system, coolant can flow to quickly to effectively transfer heat. IMHO.
       
    16. TN_Explorer

      TN_Explorer Member

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      Something to try

      I have a coworker who recently had a very similar problem with a Probe. To cut to the punch line, the Haynes manual shows the toggle valve at the top, which he had been doing. This puts the bulb that controls the thermostat at the bottom. It turns out (in the Probe anyway) this puts the bulb close to the head and at the bottom of the flow. The result was a thermostat that stayed open most of the time, but that fluctuated wildly.

      He cured the problem by turning the thermostat 45 degrees to move the bulb into the cooler water flow, and it stopped the fluctuating. Don't know if it will help, but as much as you've been through, it couldn't hurt to try it.

      -- Good luck!

      We all want to know what this finally turns out to be!
       
    17. vrytired

      vrytired Active Member

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      wtf??

      i understand that its your opinion but thats just dumb

      Q = M x C x Delta T


      laws of thermodynamics say that faster flow = better cooling
       
    18. Eneurb

      Eneurb Active Member

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      Dumb is such a harsh word... heat up the burner on your stove... red hot... then quickly run your right hand over it... now take your left hand and place it on the burner and don't move it. Which hand is burnt more???
       
    19. sabatosh

      sabatosh New Member

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      I'll vouch for that, the water moving at a higher current won't slowly cool off in the rad or pick up heat in the motor. It does sound like the thermostat isn't sitting right, that's similar to the water jacket ports being intermittently clogged with some debris. But I don't know physically the problem to look at possibilities to determine why it's behaving as such and is defective. But the irregular flow has to be caused by something clogged obviously in the only thing that could be since the heater core hoses and rad are new. The thermo or something in the water jacket...by some odd means...I don't know what could be in there.
       
    20. msmyth

      msmyth New Member

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      I'm having the same problem in my 92. Changed the engine a year ago, ever since the guage has been rising and falling. No change in heat output though. Everything's new. Radiator, t-stat, water pump, fan clutch. Not loosing any coolant. Everyone I talk to is totally at a loss. Somebody....help!
       
    21. rustbeltlife

      rustbeltlife New Member

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      There can be a blown head gasket, and still have no coolant loss. We see this occasionally at our shop. Our best tool to detect this is our radiator pressure tester.
       
    22. Kingkobra

      Kingkobra New Member

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      This is a recurring problem in Fords in general. I'll venture a guess that your in a cooler climate now and it started when the outside temp dropped...??

      rustbeltlife?? How will a coolant pressure tester show you a blown headgasket when there is no coolant loss??? That makes no sense at all....
       
    23. mckenzieslayer

      mckenzieslayer New Member

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      I have the same prob with a 94 explorer.
      For four years the guage was on the O in normal, good heat anytime, ran excellent.
      One day I noticed the guage going up to the A and back down below the N.
      This happened for a few months and just as I was wondering what all this heating and cooling off of the engine was doing to my heads, It sprung a small leak in the left front of the manifold right behind a/c pump and p/s bracket.
      Being in NY and below zero for a few weeks I would just add a little antifreeze if needed until I could get to it.
      Well it didnt let me, the leak got worse after two days and it had to be towed.
      Intake gaskets changed. Still had the same problem. Note: Thermostat was changed with tickle valve up , twice. MOTORCRAFT parts
      Same problem.
      I am also at a loss.
       
    24. satsuperman

      satsuperman New Member

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      gentlemen, i think we found a very common flaw in these explorers

      my 94 sport has been doing the same thing forever as did my 94 ranger with the same 4.0 v6. both had complete overhauls with all new parts. both of them had the same temp swings. never figured it out and just gave up. my ranger went to 220,000 miles before trade in with no problems and my exp sport has made it 54,000 so far. i just concluded that it was the 8th wonder of the world and dont sweat it if there is no problems. (both never overheated or had any cooling related issues)
       
    25. greenbeer

      greenbeer Another day, Another dent

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      My 93 did this. The problem was hair line cracks in the heads between valves. Put new heads on it, now its back to one constant temp.
       
    26. Alf

      Alf New Member

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      I have a 92 explorer 4 liters and the weather in mexico is hot. I quitted the thermostat, cleaned the radiator but the temperature turns high in the L of NORMAL. The deposit of coolant starts to boil. Someone told me that if the exhaust system is little blocked some gases of the combustion stays in the motor and increases temp. If you have some suggestions I appreciate.
       

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