Cycling Temperature

[Walt Lewandowski]

The temperature gage on my 1996 5-speed, 4WD XLT was stable for 3 years, then gradually got to where the temp gage stayed on the bottom. Ford changed the thermostat, now temp rises to just above half, drops to 1/4 then back and forth. It never stabilizes. Also, the "check engine"light cycles on/off about every other tankfull... Any ideas ??
Are they related? No bubbles in coolant and level always seems the same. Oil is OK too.

 

[NoBoundaries]

Hey Walt,

I think this might help you:
Dead Link Removed



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Tim Y.
1996 Ford Explorer

 

[Walt Lewandowski]

Thanks Tim,
But I'm still confused as to why the temperature builds then suddenly drops ( like the thermostat opens ) repeatedly. It does it more while climbing hills obviously but this is the second thermostat and it was
only marginally better. Could be two bad ones I suppose. I get gun shy - had to replace 3 cylinder head gaskets on my Mitsubishi! - but I don't smell that wonderful aroma of coolant here....

-walt

 

[Dr.Doug]

Same deal here,

I recently replaced my thermostat and now the temp guage, when crusing, moves from the lower 1/3 to 1/2 on the factory guage then back to the lower 1/3 only to repeat the process over again - non stop.

The old thermostat was stuck open and ran too cold. I replaced the thermostat with a Stant, factory replacement temp.

Why won't the engine find a temp and be happy with it?

Doug

 

[Ira]

After changing my thermostat, mine does the same thing. I believe it is just reading the temps as the t-stat opens and closes. It may seem aggravating about the frequent swings, but it is just letting you know in real time what the temp of your engine is. I don't think there is anything to worry about unless it stays very low or very high.

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Ira

91 XLT 4x4

 

[RVerdejo]

I too had the moving temp gauge. Changed from the OE Motorcraft 195 to a Jet 192. Did a flush and fill also.

The gauge still moves in cycles, so I take it that it's normal and don't worry about it anymore.

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Don't Worry about things you can control...
Don't Worry about things you cannot control.

96 Eddie Bauer AWD V8
Two other cars that aren't Explorers

 

[Dr.Doug]

Well ladies and gentleman,

Here is the fix. I too had the same problem until yesterday. I simply replaced the radiator cap with a new one and that did the trick. It too has a spring, as the thermostat has, and wears similarly. When the new thermostat was installed, it made the engine run a little warmer. The WORN spring in the radiator cap could not hold the additional expansion of the heated water. Subsequently, the water was less dense causing the engine not to cool The fan clutch would now fully engage, the thermostat would open to the max and the temp would drop. This process occurred over and over again. With my new $4.00 radiator cap, I used a Stant, my engine now warms up and stays put.

Replace your radiator cap with the same pressure specs you remove. Too high or too low will cause other problems. Remember, the radiator cap, thermostat and fan clutch all must work together and have specs to do their job accordingly.


Good luck and post your results on this topic link.

Doug


[This message has been edited by Dr.Doug (edited 01-03-2000).]

[This message has been edited by Dr.Doug (edited 01-03-2000).]

 

[barabap]

Same story for me. Mine cycles between minimum and 'R' in Normal. I asked the local dealer who told me it's normal (??). It is not. It's a bit puzzling because I checked the cap and when the temperature cycles there seem to be no water flow to and from the plenum. hence the cap should be always tight close. I'm curious to know how you can fix it. Actually I think it is not good for an engine to have this temperature cycles. The head will last much less. In particular the tension on the studs should loosen up quicker.

 

[Dr.Doug]

If your radiator cap is over five years old or has 50,000 miles on it, toss it. For four dollars and two minutes to replace it, its well worth it.

Doug

 

[SteveC]

I have the same problem with a wandering gauge. I have literally replace everthing to do with cooling and some things 2X. I also noticed when the gauge goes up, so does the engine RPM. I checked the coolant temp and it varies very little so the coolant does not heat up. I am having the gauge replaced today and well see if that cures the problem. If the sending unit sends to the gauge and the gauge in turn sends to the computer that could be the problem. Maybe it is the computer itself. I don't know but I am getting close.

 

[Walt Lewandowski]

Update - I brought the car back to the dealer and they connected their diagnostic unit and drove the car around. They reported the temperature varied from 190 to 205 degrees. Not bad, but I still question why it sometimes rapidly rises. I can see it falling quickly when the thermostat opens ( it was 20 degrees outside ) but the rapid rising scares me. I just put 1000 hard hiway miles on it and if the fluid level dropped, it was maybe 1/16th of an inch. Hard to tell. New radiator cap and after 4 hours of highway non-stop driving, I quickly pulled over and the reservoir was clear of any bubbles, in fact hardly rose at all. So no combustion pressurizing anyway.

 

[Longs]

The guage on my 93 Limited has been fluctuating for about a month. After it reaches operating temperature (about at the "o" in Normal) it will fluctuate between that point and about halfway between the "o" and the cold line.

I tried Dr. Doug's suggestion about a new cap, but it didn't seem to make any difference. I also got the Stant cap, 13psi. I noticed in the application guide that 1994 uses a 16 psi cap, by the way. I'm thinking that I'll change the thermostat; it could be going bad or hanging up. I changed it back in May when I had to replace the water pump, so I'll just flush the system and replace it again.

I don't believe my fluctuation has anything to do with a head or gasket problem, because I'm not getting even brief signs of overheating. I had a 2.2L turbo Chrysler, and when it blew a head gasket, the temperature would go higher than normal, especially before the thermostat opened for the first time. It would then continue to fluctuate, and continue to go higher than it should. Eventually, I could hear the combustion gasses bubbling in the overflow bottle after I'd shut off the car.



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"Whoever said you can't fool all of the people all of the time, was a damn fool" Vincent K McMahon, January 1999

 

[Gigantor]

Hey everybody out there! We do NOT have a problem with our thermostats. They are just active! Ok I know it may not look to good the temp rising and droping down but the 10-15 degree temp change will NOT kill your engine! This is from 2 mechanics telling me this. I trust these guys!
By the way is there a trick to taking off the bolts to get to the thermostat? It took me 3.5 hrs! That is crazy. I am sure you could have taken off the alternator and belt but that would have taken just as long. I spent over an hour getting the top left bolt out and even longer getting it back in.


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Nick
'93 XLT 4 Door 4x4

 

[martina]

Hello all. I too am having this dancing temp guage on my 94 xlt. Have only owned this vehicle 3 weeks, so I can't give any more history. Thermostat changed 195, flush/fill, new cap, and no other signs of head gasket troubles. This is driving me nuts! I have great heater output, but with these computer controlled engines I can't believe this is not affecting performance/ mileage somehow. If anyone has a real fix for this I'd love to hear it. On another note this truck runs great but It seems to have a resonating type of growling noise on acceleration, which seems to be coming from drivers side front. Not a constant noise, more of a cycling type. Anyone have any clues? Truck was just safetied so I know the standard stuff is ok. ie:brakes, bearings, front end parts, exhaust....etc.


Any info appreciated....Al

 

[Syder-1]

In order to get at that one ultra annoying bolt on the thermostat housing. On my 1991 I remove the tension pulley first. This allows easy access to that well hidden bolt. Have the whole thing down to a science, less that an hour. If there is an easier way I would love to hear about it.

Syder-1

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doo doo happens

 

[raven2]

Well I too have the same mystery guage, but another problem associated with mine is heater output fluctuation, It will be hot at floor outlet on low fan, but with fan on high, I get just about cold air, (with a warm engine) Is this a T-stat problem?

Second, I have a swishing sound under the dash during accelaration, especialy when parked, my guess this is air in the heater core, if so how do get rid of it?
Tim

 

[Ira]

Syder-1

The easiest and quickest way I have found to remove the t-stat bolts on my 91 is to use a 1/4" drive rachet, extension, and swivel. You can work around everything that is in the way by using the swivel. Another thing that is helpful in this situation is a telescopic pencil-type magnet. Got mine a Walmart for about $2. It is helpful to use when you get the bolts loose. You can keep the magnet at the socket and not drop the bolt into the Land of the Lost. You can also use the magnet to place the bolt back in place in the hole. I changed mine in 30-45 minutes...even with the kids running around Dead Link Removed.

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Ira

91 XLT 4x4

 

[Syder-1]

Thanx Ira. I'll invest in a 1/4" swivel and a new 10mm bolt. Dropped the socket and it found a very nice resting place in the motor somewhere. Looked all over and it is now part of the 4.0 liter engine (yahooo)

Syder-1

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doo doo happens

 

[FMNavajo]

I have a 92 Navajo and I've had the same problems with the temp gauge. Mostly it occured with a load while climbing the hills in the Mountains here in Northern Ca. I've changed the water pump, Thermostat, flushed the radiator, etc... No change.

I am curious if anyone has thought about the Trans fluid causing this fluxtuation in the temp? It does run through the radiator and most of the time the radiator will actually heat the trans fluid rather than cooling it.

My question is that, "has anyone installed a trans cooler on this model of truck"? And how hard was it to put and how does it effect the temp gauge?

[This message has been edited by FMNavajo (edited 01-20-2000).]

 

[Jeff]

I too have started having a problem on my '97 with 60K miles that began a couple of days ago. On the 97 we don't have the word Normal on the guage but instead a thermometer symbol. For 2 1/2 years it always, and I mean always even in Las Vegas heat, ran just below the base of the thermometer.

Now it fluctuates rather quickly with the indicator going up half way between the thermometer and the H symbol. And just as quickly it drops back down but never to the point just below the symbol. Alarming especially since I haven't seen this before. Now it runs just above the base with fluctuating. If I turn on the heater the temp drops somewhat. There are no bubbles and I'm not losing fluid.

Now this may be more coincidental than not but now I'm having a high idle problem. With outside temps in the 60's, the idle is now at 1100-1200 RPMs instead of the usual 600-700.

Suggestions?