Explorer 1992 - Overheating problem

[Auto2510]

my Explorer XLT 4 wheel drive has an overheating problem. I changed in the meanwhile the radiator, the thermostat, the water pump, the fan, the fan clutch, and the shroud. The outside temperature is currently - southern Utah - around 100 degree F. During normal operation - driving on a highway - the temp gets up to the "A" of NORMAL in the gauge within 1 min. Once the thermostat has opened the needle goes back to "O". There is no problem as long as I am driving. As soon as I get to town the needle goes up a little bit. Cruising in town isn't a problem either. When parking and letting the car run in idle mode I can watch the needle to go up to "L". I checked the fan. It is running fast. Usually I then turn the engine off. The needle of the temp gauge slowly gets back to "R". When starting the car after having done e. g. shopping the needle goes right away up to "L". It takes maybe 2 minutes of driving and the needle is going down to "R". I did clean the radiator by using a water hose. The water level in the reservoir is unchanged; i. e. it is at the level I filled it up to months ago. What could cause this (strange) behavior?

 

[vq5speed]

Sounds like your have a bad gauge or bad temp sender or sensor. When the gauge does get to the "A" after one minute of driving have you pulled over to see it its really getting hot.

 

[surf]

You might want replace the radiator cap if you did not aleady do that. Also you can sometimes get a bad thermostat. What brand did you install?

 

[larrydd999]

I had the reverse problem - the temperature would never go above the 'N', and all external tests (FLIR gun, etc.) indicated the engine temperature range was about the same as our other 'EX. I ended up changing the sender and the gauge started working better, then cleaned the various connectors between the sender and the gauge and now it's working fine. Since it's inexpensive and relatively easy to change, I'd replace the sender.

 

[MrShorty]

Your symptoms remind me a lot of when my fan clutch was bad. You don't say who you got the fan clutch from, but some of the aftermarket brands can be bad out of the box.

Visual check for rotation is not an adequate test of the fan clutch. One of the "by the book" tests I used was to remove the fan clutch, disengage the outside end of the "spring" from its notch, and rotate the spring 1/4 turn CCW (if memory serves correctly). This will force the fan to be engaged. Reinstall and test drive. If the overheating issues go away, then a bad fan clutch is indicated. If the overheating issues continue, then the fan clutch is probably fine, and you can re-engage the spring to restore normal operation.

 

[Auto2510]

First - I am sorry to respond that late but the mail from the forum ended in my spam file. I have exchanged almost everything in this cooling system with one exception - the temp sensor. I bought one at NAPA and according to the guy behind the counter it should be the right one. I don't think that. The one I bought has two pins whereas the one in the car has just one pin. The one in the car has a threaded pin like a spark plug, the one I bought has a normal two pins socket. I guess I have to get the replacement sensor directly from Ford

 

[Roadrunner777]

There are 2 sensors. The one with a single pin is for the gauge. The one with 2 pins is for the engine control computer (PCM).

 

[natenkiki2004]

Follow the vacuum line from your charcoal canister to where it connects to the bottom of the throttle body, right below that will be the 2-wire ECT plug. I can see mine pretty easily but don't have the AC compressor anymore. When I removed it, maybe only a few drops of coolant came out. You don't need any rags or containers on stand-by for a spill.

 

[Auto2510]

In the meanwhile I found the right temp sensor and I am going to install it; however I have my doubts that this is really what's going to cause the problem. The comment made by MrShorty triggered a further investigation of the fun clutch. Although the fan clutch is relatively new (less than 1 year) I checked it and it isn't doing what MrShorty described. Even if the car is cold (early in the morning) the fan isn't running freely. I checked the fan a couple of days ago after driving in town at very high temperatures (above 100 degree F. The fan shows the same resistance as this morning the car and the outside temperature being cold (in the 60 ties). It seems that the fan clutch is causing the problem. I have still the fan clutch replaced a year ago and this one is also not turning easily. What does turning freely really mean? Does it mean that it turns a couple of rounds once pushed on one of the blades?

 

[Anime]

When driving in hot weather with the A/C on, it's actually pretty common for the temp gauge to read over into the A-L range of NORMAL. If it's 100 degrees outside, it's even hotter above pavement that's absorbing and radiating heat, and the air going through the A/C condenser is that hot, hot air, which makes the air going through the radiator (after it goes through the condenser) already hot, so the engine isn't cooled as well.

The fan clutch should spin a few rounds freely when cold, as in the engine hasn't been operated for hours. It will probably only spin a few times due to friction, but if it doesn't spin and there is resistance when cold, it's probably not working as intended.

The other thing is the fan clutch might not be the correct one. Ford made regular duty and heavy duty fan clutches for the Explorer. 5-speed manual transmission equipped models usually had the regular duty (though those with "super engine cooling" had the heavy duty), and those with automatic transmissions had the heavy duty clutch.

In the aftermarket, there are regular duty, heavy duty, and severe duty fan clutches. Severe duty is for hot, hot climates when the air temp and having A/C on really requires moving air.

If you have a regular duty fan clutch on a vehicle with an automatic transmisson, and you're trying to use it in 100 degree weather with the A/C on, it's just going to run warm because the fan clutch can't move enough air to keep up.

It's pretty easy to tell a standard duty fan clutch from a heavy duty or severe duty fan clutch.

A standard duty fan clutch is thinner and barely has any fins, like this:

A heavy duty fan clutch is thicker and has lots of fins, like this:

A severe duty fan clutch looks like a heavy duty fan clutch, but just engages even more.

You may also be using a fan that's incorrect for the application. Many times, an aftermarket fan is used, and it winds up being the 9-blade Dorman fan. They can work ok in more temperate climates, but will not be up to the task of cooling a vehicle with an automatic transmission in 100-degree weather. They can also cool poorly if the spacer is not used, as the fan will not be positioned in the shroud correctly for maximum airflow.

The correct fan to use is the 10-blade replacement Motorcraft fan from Ford, or the similar aftermarket knockoff from Depo:

You can usually also use an 11-blade fan for later model 95-01 Explorers.

You should also be sure you're using good coolant and in a 50/50 mix with water. Dex-cool antifreeze like Prestone (even the regular green Prestone is now the same chemistry as Dex-cool) isn't as good as using regular green ethylene glycol coolants or newer alternatives.

The best coolant to use for the 4.0L V6 is probably either Zerex Green (green ethylene glycol, same as the Explorer originally came with from the factory), or Zerex G-05, which is a yellow color coolant that is what new Ford vehicles come with from the factory. Both coolants are available from NAPA. You can also just get coolant from Ford, as they sell both the green and yellow, but it generally costs more than the Zerex, and the Ford coolants are just Zerex coolant in a Ford labeled bottle.

 

[Auto2510]

Thanks for the very detailed explanation, The currently installed fan clutch is most probably an aftermarket product. I bought it from NAPA. It is also a heavy duty one since it looks like the one shown in the picture. I tried to turn the fan just a couple of minutes ago again. The temperature is now approaching the 100 degree F but the situation is identical. It doesn't turn freely. I have changed the anti-freeze a couple of months ago and I did buy Zerex. I mixed it 50: 50 but that didn't have any influence on the performance now, I checked the number of blades on my fan. It has 9 blades. I have a maybe curious question. You wrote that it is normal that the needle of the temp gauge is in the range of the "A" to "L" once the weather is really hot with the A/C on. That is the situation when I am in idle mode after having driven the car for some time in hot weather. If that is normal what is going to happen if I keep the engine running without touching the gas pedal?

 

[MrShorty]

I have found that turning the fan clutch by hand is not a good way to test it. The viscous fluid in the clutch will always show some resistance to rotation. To really test it, you need to test it with the motor running.

I recall when I had some "getting a bit too hot" issues on mine, I would onhly sometimes hear the fan roar when it got hot. When it did roar, the temperature would stay more normal (or it would kick on and suddenly cool down). When it did not roar, the temperature would rise. The test I described above is the most reliable test I have found in my limited experience.

 

[Anime]

The currently installed fan clutch is most probably an aftermarket product. I bought it from NAPA. It is also a heavy duty one since it looks like the one shown in the picture. I tried to turn the fan just a couple of minutes ago again. The temperature is now approaching the 100 degree F but the situation is identical. It doesn't turn freely.

Almost all aftermarket fan clutches for the Explorer are made by Hayden. They are ok, but the OE Ford clutches are "better", or at least give more of the performance that you'd expect from them for particular applications.

Do you know for sure if it is a heavy duty or severe duty model? Sometimes the severe duty clutch can cause slightly high temps since it puts more of a load on the engine, in order to move more air to cool the engine.

I have changed the anti-freeze a couple of months ago and I did buy Zerex. I mixed it 50: 50 but that didn't have any influence on the performance now.

Zerex Green or Gold G-05 isn't the same as regular Zerex. Did you flush out all the old coolant? Mixing one kind of coolant with another can lead to sludge and deposits in the cooling system that affect flow and cooling abillity. The only way to flush a system is to either fill it with water a few times, run the engine, then drain it, or just run it with a hose attached to a flush adapter.

I checked the number of blades on my fan. It has 9 blades.

Is it the OE Ford fan, or does it look like this?

http://shop.advanceautoparts.com/wc...e//527/large/19010142_dor_620112_pri_larg.jpg

That's the Dorman fan.

Like I said, it can be ok, but with an auto transmission, in hot weather, you are WAY better off getting the 10-blade, either from Ford, or get the knockoff Depo version on ebay. It will move more air.

I have a maybe curious question. You wrote that it is normal that the needle of the temp gauge is in the range of the "A" to "L" once the weather is really hot with the A/C on. That is the situation when I am in idle mode after having driven the car for some time in hot weather. If that is normal what is going to happen if I keep the engine running without touching the gas pedal?

Nothing different should happen whether it's at idle without touching the gas pedal, or at idle after having driven the vehicle.

Keep in mind engine temperature, with A/C load, is also a function of engine speed. If you drive at 45-55MPH on the highway, on a 100 degree day, the engine temp gauge might read in the M-A range of NORMAL. If you increase speed to 65-75MPH, the wind resistance and the higher RPM might put the temp gauge needle into the L of NORMAL.

At idle, sitting in traffic where other vehicles are spitting out hot exhaust gases and expelling hot air from their engines as well, there isn't any really cool air to use to cool the engine as well, so that combined with having the A/C on is going to cause the engine to be at a higher temperature.

You can check to see if the A/C load is causing the temp gauge needle to be over in the A-L range by turning off the A/C. If the needle goes down some after 5-10 mins, you have your answer.

The real test is whether the temp gauge needle reads in the middle R-M of NORMAL, with the A/C off, during normal operation on mild 60-80 degree days. If it does that but just reads in the A-L range of NORMAL on hot 100 degree days with the A/C on, that's just how it is.

My guess at this point is that although it's probably normal operation, the 9-blade fan may not moving enough air, and/or there might be some coolant issues depending how well the system was flushed or how clean it is.

You might get some improvement with the 10-blade fan, which I would suggest anyway, on a vehicle with an auto transmission being used in 100-degree weather. It may only give a small improvement on 100 degree days, but the current setup with the 9-blade fan might be at it's limit, and the 10-blade fan will give additional cooling headroom for 110+ degree days.

 

[Auto2510]

Hi, I am kind of confused. I bought today a new fan clutch (severe duty). I have the feeling that the new one isn't different from the one currently installed. The socket for the fan blade isn't turning easily. It is as sticky as the one in my car, I guess I have to test the old one thoroughly before I install the new one.

 

[Anime]

I'm doubtful you really need a severe duty fan clutch, a heavy duty fan clutch might be better, unless you just really want to have it for the few days/weeks of 100 degree weather.

You would probably be better off getting the 10-blade fan and trying that out on the fan clutch, either the one that's on it now, or the original fan clutch if you still have it.

 

[Auto2510]

Thanks again for the help. I am not really convinced that my fan clutch is bad. Therefore, I am going to test the fan clutch. I called on the different repair shops in town and one of them is equipped with a strobe. Thus, I want to see what revolution range the fan is running at once the temperature is going up in the range of the "L" in NORMAL. In case the fan clutch is engaged the revolution of the fan clutch should be comparable to the revolution of the water pump. If that isn't the case I am going to replace the fan clutch.

 

[Anime]

The aftermarket 9-blade fan that's on it now, no matter what fan clutch it is attached to, or even if it was driven directly off the water pump with no fan clutch, can only move a certain amount of air.

The 10-blade fan can move more air than the 9-blade fan. This is important because having a 10-blade fan on say, a heavy-duty clutch, can move more air than a 9-blade fan on a severe-duty clutch.

Thus, my suggestion is for the 10-blade fan with either the original Ford heavy-duty clutch (if you still have it) or for the severe duty clutch you already installed if you just want to go with that for whatever reason.


Having a 9-blade fan with a severe duty fan clutch is basically the worst of both worlds, the fan clutch will constanty be keeping the fan spinning hard to try and move air. The harder the fan clutch engages, the greater the load on the engine, and the higher the engine temperature gets.

It's basically a vicious cycle where the engine temp increases because the fan clutch is fully engaged to try to spin the fan as fast as possible to move air to cool the engine.

With the 10-blade fan, it wouldn't need to spin that hard, the load on the engine would be much less, to move the same amount of air, to cool the engine.

 

[Auto2510]

Explore 1992 - Overheating problem

Actually, I wanted NAPA to get me the 10 blades fan but NAPA couldn't get it. Therefore, I agreed to order another fan. It is an original Explorer fan with 12 blades. According to the NAPA guy it should work with the fan clutch. As soon as I get the proof that my currently installed fan clutch is really bad I am going to install the severe duty fan clutch in combination with this 12 blades fan.

 

[Anime]

Not sure if the 12-blade fan will work. It might.

Even if it does mount to the fan clutch, you also want to be sure it is positioned correctly relative to the fan shround to pull the air. The fan blades should be about halfway in the shroud. A few millimeters one way or the other is no big deal, but you'll need to use a spacer if the fan is too far in.

The only thing to worry about the 12-blade and severe duty combo is that the cooling may be 'too much' during the winter months, and even with the fan clutch at its lowest, the engine might have trouble maintaining the correct operating temperature on cold days. It will also waste gas and affect mileage. This is why the 10-blade and the heavy-duty clutch is usually the preferred setup.

You can always run the severe duty and 12-blade in summer and a heavy duty with the 10-blade in winter, or maybe just keep the 9-blade and use that during winter if what you have now is a heavy-duty clutch and not the severe duty.

 

[Auto2510]

Thanks to all of you who helped me resolving the issue.
The car was tested in a repair shop by measuring the temperature of the different components under several conditions. The shop used a kind of a temp gun. The temperature of the engine was 200 degree F briefly after being driven in the shop. The car was started and was running in idle mode and at higher revolutions. The temp gauge reacted by moving the needle of the gauge to the "L" of NORMAL. However, the actual temperature of the engine didn't change at all. Even running the car at higher revolutions and covering the radiator with a piece of cloth didn't change the actual engine temperature but it did lead to a higher temp reading of the temp gauge. Thus, it was obvious that my cooling system is fine but the temp sensor was bad. I was kind of surprised to see that because the temp gauge looked fine to me whenever driving the car on a highway. I took the temp sensor out and replaced it by a new one. The result is that the needle is now between the "N" and "O" of NORMAL. The current outside temperature is 90 degree F. I am really looking forward what I am going to see once the temperature gets beyond the 100 degree F. As consequence from this testing I did return the severe duty fan clutch and the 12 blades fan