Replacing fan clutch w/water pump?

[Erika]

Hey there, I'm new here and have had some overheating/high idle problems with my 2001 V6 explorer. Have been reading past threads on here for hours... Problem is very intermittent. Will run perfect for awhile, then, maybe after 30-40 minutes of stop and go city driving the idle will come up, from normal around 500 rpm to around 1000. Once that happens, the temp starts rising. Slowly.. but it will creep up very steadily. I don't think this is a faulty sensor because when stopped, I can hear coolant bubbling and everything just "feels hot." If I go from drive to park, the idle jumps up even higher. Happens with or without a/c on. Turning on heater doesn't seem to help. This doesn't happen every day, rather, on a weekly basis. I can't figure out what triggers it, if its mileage, or time or what. Doesn't do it cold, only at normal op. I've replaced the thermostat already. I've squeezed hoses, they're good. I've checked for vacuum leaks and can't find any obvious ones. Water pump is not leaking, no wobble at the fan. I have the idle air control valve sitting next to me, its gonna get cleaned up, but I don't think that's it either. One culprit may be the fan clutch, as when its cold, it does not turn freely like from what I've read, it should. I read somewhere that if you replace the fan clutch, the water pump should be replaced as well since they both utilize the same shaft and when one fails they should both be replaced. What's your opinion on this? Also, is there anything else I should check out before replacing the fan clutch and/or water pump? Car has 218,000 miles and has been really good to me up until now. Sorry this is so wordy..

 

[joshuaj0214]

What engine is in the truck? The over heating could be the fan clutch and/or the water pump, but it wouldn't make the idle rise I don't think.

 

[Erika]

Its got the 4.0L SOHC V6. That's what I think too, hinky. I've read many posts where the idle increases as a result of overheating, but in mine, the idle increase preceeds the rise in temp.

 

[CDW6212R]

I would hope that the fan clutch is your problem, especially if that is the original mileage.

The idle rpm will rise a lot on purpose when the coolant temperature begins to get too hot. That idle increase is what saved my engine when I had my electric fan stop working, that is what got my attention. I hit 270 degrees which fortunately only ruined the thermostat.

I would suggest getting some kind of OBDII device that can read the actual temperature in real time. You don't want the temperature to go much over 205-215 degrees, that's likely when the idle starts to go up.

Don't worry about the water pump and fan clutch servicing being at the same time. Mileage of the part is most important, not the failure of the other part. Check that the coolant is very clean, use as little anti-freeze as possible, and use an additive like Water Weter. Regards,

 

[scucci]

The idle speed increase is caused by the pcm going into limp home mode due to a rise in cylinder head temperature. Your dash gage is not very good at showing this, but the head temp sensors are very precise. When hot the fan should not make a full revolution when you give it a heavy push. When cold it should spin about 1 revolution. The fan only is needed below about 25 mph. Above that it would not contribute to overheating. Remove the radiator cap and get the engine hot. Then look for coolant flow in the radiator - it should be very evident if the water pump is pushing coolant properly. I have seen new thermostats come apart and cause the same symptoms you have. Also air pockets can cause low coolant flow. You might have a local mechanic check for exhaust gas in the coolant to help rule out a cracked head. If you can check the temperature of the top and bottom tanks when the overheating occurs it can help pinpoint the problem. The normal temperature differential between top and bottom tanks is 7 to 11 degrees F. Smaller differential indicates a lack of cooling air flow - fan clutch or air flow blockage, larger differential indicates a lack of coolant flow -blockage or broken water pump. If you can find a pipe plug in the coolant passage in the cyl block you can test pump pressure - generally around 25 PSI.

Hope this helps a bit,
Scucci

 

[Erika]

Thanks Don and Scucci,
Yes, the mileage is original, mostly highway. I bought it 6 years ago at 40k miles. I've maintained it fairly well, and its only recently (since paying the damn thing off) that its started to show its use. The fan is not making a full revolution, hot or cold. With a hard push, it only moves a few blades around, this is what makes it suspect to me.

I've checked for a blown head gasket, no oil in water and vice versa. No excessive water in the tailpipe or anything like that. The cooling system was just flushed 10k miles ago. Its healthy and green. When I replaced the thermostat, I burped it thoroughly, so its not showing any bubbles. I also made sure coolant was moving properly, so I'm fairly certain the pump is alright. In addition, there is no wobble to the pump shaft and no weeping.

Looks like I'll see if cleaning the IAC valve has any effect, then I'll find myself some kind of obiwan device Don mentioned to get some actual numbers. Will keep you posted... thanks!

 

[CDW6212R]

The fan clutch and thermostat are the best guesses from what is posted. Thermostats are not as reliable as people think, even when new. But once they do work right to begin with, they usually last many years. Night,

 

[Erika]

Well, at least they're cheap! I may get another one, just in case....

 

[Cobraguy]

A thermostatically controlled fan clutch should be stiff when cold. That's why the fan makes so much noise on cold start up...then quiets down after a couple of minutes. At normal operating temp, the fan should NOT BE LOCKED OR STIFF. If so...it's bad. At normal temps, the fan should be pretty free. When your vehicle is overheated, the fan should be almost locked solid. Very stiff. If not, it's bad and replace it. Check this out and if it fails, a new one may be your fix. Now, keep in mind that if your radiator and condenser are plugged enough to not allow sufficient airflow, you will over heat and your fan clutch will not operate properly. It must see airflow. Check for clean fins. A new thermostat wouldn't hurt either...but get a good one. Not a cheap one. Get a Motorcraft if you can. NAPA and Carquest also have a high end line.

If you can get to a shop with an exhaust gas analyzer, carefully get the radiator cap off when warm and insert the gas probe into the radiator. See if there are any exhaust gasses present. You could have a cracked head here...and you won't have oil in the water for a head cracked into a combustion chamber.

25 psi for pump pressure? That seems high to me...especially since the cap is probably only rated at 17 psi.

 

[CDW6212R]

If you go after another thermostat, I suggest the Failsafe line. Motorad was the original maker, but it's carried in stock by O'Reilly's under a common name now. Those when overheated will not fail closed, they fail open. That won't affect anything up until the overheating, but afterwords the coolant will still flow.

I had a fan issue at work(99 work truck),and if not for the Failsafe unit, I would have been broken down until the thermostat was changed. I was able to drive it after the fan was running again. I changed the thermostat about three months later. Regards,

 

[Erika]

Ok, well now I'm really confused on this fan issue. Everything I've read, including the Haynes manual states that the fan should turn freely when cold. When the car is turned off at normal op. temp. the fan should be stiffer, no more than one revolution with a hard push. Currently, the fan is stiff whether hot or cold. Not "locked up" by any means, just stiff. I would venture to say this is how its supposed to be if it were warm, but not how it should be cold.

As far as the thermostat goes, the one I took out, while a bit junked up, was functional. The one I put in is a Duralast. I don't know if this is high end or not, its just what the salesman gave me. If you guys say its crap, I'll buy a Failsafe or a Motorcraft, just to be safe.

As far as a cracked head goes, doesn't that usually happen when it seriously overheats? I haven't let it get that hot. Its never been near the red.

Personally, I'm trying not to take it to a mechanic since I really feel I just get ripped off around here. Recently, I was almost sold a new transmission when the alternator went bad. I got lucky on that one. I feel certain that I will have a cracked head and need a new engine according to the mechanics around here. So, again, thanks for the feedback, all of it is helpful.

 

[CDW6212R]

For just the high mileage that you have, I would feel very comfortable investing in a new fan clutch. Those do not fail often, but they don't usually ever last as long as yours has. If you think can verify that you have some flow in the radiator, I'd wait on the thermostat for the moment.

 

[wyochimneysweep]

when it warms up run it at a higher engine speed and put a piece of paper infront of consedo and it should suck tightly to the consedor if there is good air flow

 

[Erika]

wyochimneysweep, do you mean "condenser?" I'm not sure what you mean by "consedor"...

 

[Texan01]

I'd be willing to put money down it's either a bad coolant temp sensor for the computer (there are two on there one for the gauge and one for the computer) or the t-stat is sticking.

Get the car good and warmed up and even use the A/C and then take a plastic bag and see if it gets pulled into the grill with the engine running. If it does the fan & clutch is fine.

Does it run hot on the highway or puttering around town? if it runs hot on the highway then chances are very good it's a clogged radiator. I ran into that with my '95 a while back.

I've had the coolant temp sensor fail on mine several times over the course of 230,000 miles. They'll get out of range and the computer will start doing weird things with the fuel mixture which can cause it to lose power/run hot or shut off the A/C and kick the idle up when it thinks it's overheating.

 

[Erika]

Texan, it only runs hot puttering around town, not on the highway at all. The a/c doesn't shut off, however, it doesn't run as cold as it should at idle. Is there any way to test the coolant temp sensor, or should I just replace it as a process of elimination. If so, where's it located? Nevermind, I'm sure I can look it up.

 

[CDW6212R]

The coolant temperature sensor is right next to the thermostat, but you should avoid that greatly for the SOHC. That SOHC thermostat housing and the sensors are extremely fragile. It's easy enough to work with the thermostat and housing, but the sensors very often will be seized to the threads.

The result is often a ruined thermostat housing, and it is only available as a complete Ford set of parts for over $250. Avoid messing with those sensors unless you know absolutely that they are bad.

What mileage does your truck have? You can listen to 10 different guesses of what your truck's problem is. You can replace every part of the coolant system.

Why do all of that when you have a clue already? Almost all car problems can be corrected by basic tune up items, proper general maintenance.

You have high mileage on that vehicle. Begin by replacing the known high mileage parts which could cause the symptoms. Thus again, replace the fan clutch, whether it turns out to be bad or not. If the coolant is old, replace that also, and don't use 50% anti-freeze. 25% is more than enough for places without sub zero weather. Regards,

 

[justchecking]

On my 2002 V6 the temp sensor is held in by a little wire clip. Use a small screw driver to pull out on the clip then the sensor comes right out. I think I paid about $12 for a new one. Yours may be the same type, but it doesn't sound like yours is bad.

 

[Erika]

Thanks everyone,
I'll change the fan clutch tomorrow and let you know if that does the trick. Could be awhile till I know since the problem is so infrequent.

 

[wyochimneysweep]

blow out the raditor with the garden hose also while you gotthe fan out. go from the inside out as to reverse the flow and get most of the junk out of it to. then you will be good to go