No heat, gauge flutuating

[Bofronado]

2003 Ford Explorer, 4.0 liter; Has low or no heat, the temp. gauge is normally pretty much right in the middle of the range. It will all of a sudden go up to hot for a second or two and then return to the original level. Fluid level was a little low, maybe a pint, and I do not see any leaks at all. Motor seems to idle well and no grey smoke. There is a pretty good chirp from the serp. belt, and the tensioner looks like it moves in and out 1/2 to 3/4 inch when running. That many need replacing. Vehicle seems to warm up very slowly. Any suggestions on where to start?

 

[Mr Dubya]

When in doubt, replace the thermostat.

That's at least the first step I live by, half the time I work on someone's car that seems to be the culprit.

And for 8 or 10 bucks, not only is a cheap way to eliminate one factor, but itl'll give you a chance to take a peak at the inside of the thermostat housing.

I would say give that a shot first and see what happens.



-Dubya

 

[apanello]

Replace your t stat before you overheat your engine....

 

[Bofronado]

When in doubt, replace the thermostat.

That's at least the first step I live by, half the time I work on someone's car that seems to be the culprit.

And for 8 or 10 bucks, not only is a cheap way to eliminate one factor, but itl'll give you a chance to take a peak at the inside of the thermostat housing.

I would say give that a shot first and see what happens.



-Dubya

The previous owner replaced the old thermostat 12/27/12, so it being bad seems unlikely. Guess it wouldn't hurt a lot to change it though.

 

[Bofronado]

Checked the coolant level again and it is about a pint low again and I can see that some fluid came out of the reservoir. The level seems to always be the same. I do not see any oil in the antifreeze or antifreeze in the oil. The engine runs well, and does not smoke. Hoping it isn't a head gasket. The belt is pretty noisy and the tensioner is doesn't seem real strong. The belt looks okay and within the marks on the tensioner.

 

[Vic_Ferrari2002]

The truck warming up slowly makes me think the thermostat is stuck open. I have seen it happen to brand new thermostats. As for the fluctuating gauge...Does it happen multiple times during a trip or does it only do it once during a trip? Kinda makes me think that you have air trapped in the coolant system. I would go to your local auto parts store and get a new thermostat and rent a coolant pressure tester just to see if where the leak might be. If your constantly adding coolant it has to be leaking somewhere. Hopefully external.

Keith

 

[Bofronado]

The truck warming up slowly makes me think the thermostat is stuck open. I have seen it happen to brand new thermostats. As for the fluctuating gauge...Does it happen multiple times during a trip or does it only do it once during a trip? Kinda makes me think that you have air trapped in the coolant system. I would go to your local auto parts store and get a new thermostat and rent a coolant pressure tester just to see if where the leak might be. If your constantly adding coolant it has to be leaking somewhere. Hopefully external.

Keith

Okay, thanks for the tip. I dove the SUV for 35 miles this morning, partly interstate, partly 55. It spiked up 3 times on the way up and 3 times on the way back, so about every 10 minutes or so. Most the time it would not even get to high before it started falling back down. The air coming out of the heater would go from warm to really cold right after the gauge spiked up. I think the coolant is coming out of the reservoir, but not sure. As stated before, it is about a pint low, which is exactly where it was before, it is not like it is blowing all the antifreeze out. Renting a tester is a good idea.

I know that my Hayes manual talks about the belt tension could cause a problem, but I have trouble believing that.

 

[JCR]

Had a very similar thing happen with my 2002 XLS 4.0 and it turned out to be the Temp Sensor mounted in the T-stat housing. I also had to replace the upper and lower T-stat housing as it was very deteriorated and was leaking fairly undetectable (until I looked really hard).

 

[ponkotsu]

Okay, thanks for the tip. I dove the SUV for 35 miles this morning, partly interstate, partly 55. It spiked up 3 times on the way up and 3 times on the way back, so about every 10 minutes or so. Most the time it would not even get to high before it started falling back down. The air coming out of the heater would go from warm to really cold right after the gauge spiked up. I think the coolant is coming out of the reservoir, but not sure. As stated before, it is about a pint low, which is exactly where it was before, it is not like it is blowing all the antifreeze out. Renting a tester is a good idea.

I know that my Hayes manual talks about the belt tension could cause a problem, but I have trouble believing that.

If the belt is slipping you won't cool the engine and you won't get heat because of no circulation. But I think you can visibly see and hear if it was slipping that bad. Like the others said, check the thermostat first. Just because the prior owner already changed it means nothing. Those are notoriously bad parts unless you go OEM. Could be some air in the system also. I think there is a special procedure to bleed the heater core. Another rare failure is a delaminated hose where the inside starts to close off the flow. Could be crud in the system. If it was just the temperature gage, that wouldn't explain no heat.

Also could be much lower than you think. Are you checking level at the overflow bottle or at the filler point? I'd double check the filler tube. I under filled my engine when I put the intake back on a few weeks ago. It was getting really hot but I had no heat.
Its a tough one to trouble shoot sometimes.

 

[Bofronado]

Okay, I changed the thermostat today and put on the new tensioner. I think it was the problem, but not sure yet. The shop that put the previous thermostat in didn't have the right o-ring, so the put in a narrower one and siliconed the gap. Unfortunately the o-ring I got from Advance was not right either, so there is a very slight leak. The old thermostat was closed but the little flat plate assembly at the bottom fell off of the unit. Not sure what that will do, but probably nothing good.

 

[pet575]

I know you've replaced the t-stat, but have you also checked the temperature which your coolant is mixed to tolerate? Could be that with the cold weather your coolant is getting a little slushy in the radiator and not circulating as well as it should-causing heat ups. Something easy to check with a hydrometer: http://www.google.com/url?sa=t&rct=...=LscuH5n8tTwQlD_VrqkUlg&bvm=bv.57752919,d.aWM

 

[Dead_Goldstar]

I have a 2005 Ford Exp sport tract and I have run into a temperature gauge issue is use to sit about in the middle but now it's sitting at 1 notch above the cold end. I'm still getting lots of heat and no over heating problems the antifreeze hasn't been changed in about 3 years could this be it. Could it possibly be the thermostat but there is lots of heat so it has to be opening. Possibly could be the temperature sensor not working but it does move just not to its normal middle of the gauge position. I would appreciate any help you could offer trying to resolve this issue.

 

[Bofronado]

starting to think it is the heater core is partially plugged. If I turn the fan to low I seem to get some warm air, when I turn the fan up, it quickly turns cold again.

 

[Bofronado]

To follow up, I think the heater core was the problem all along. I blew compressed air back through the core several times to get all of the junk out of it and I am now getting some heat. Would have liked to have flushed it with water, but at 10 degrees that would have been a disaster. Put some flush cleaner in the coolant and will let that circulate for a couple days and then drain, flush and fill.

I took the outlet house off the heater core and routed it into an antifreeze jug and started the engine and only a few drops went into the jug in 2 minutes. I put some compressed air back though it yesterday and it seemed to be going through, but that did not do the trick. Never seen anything that is that plugged. Also, the think the squeak I was getting from the belt was because the water pump could not more antifreeze through the heater core, as that has gone away now. Any thoughts?