Overheating at idle, but not at speed, points to the fan(s) not operating correctly; however, your comment of "pressed the accelerator gently for 20 seconds or so and it cooled back down" seems a bit unusual.

Is the fan operating when you are at idle and the temp indication is hot?

 

Maybe a dumb question, but how would I know if the fan is operating while I'm idling? By its noise? What does it sound like?

Also, I added some coolant this morning, because it was at the "min" level and I just drove about 5 miles to pick up my lunch and had no problems. I even sat in the parking lot at work (while my damn food got cold) letting the engine idle and watching the temp. No overheat. Maybe adding the coolant helped/fixed it? It wasnt that low to begin with so I dunno...this is getting fishier and fishier

 

well it all depends if your fans r turning on, if they r than that is a big prob.
the normal overheating prob with the focus is the resistor between the fan schrowd, pull the resistor off and dont look at the resistor, look at the electrical plug. i had the same prob except i dont think it cooled down after pressing the accelerator. if u do find out it is the plug replace both connector and resistor. i went through 3 connectors before i finally bought the resistor and ever since i havent had a prob.
and if u dont get the parts soon, just keep your cars heater on defrost cause that trips the fans to turn on.

 

It could be a short in the line somewhere causing the gauge to read improperly. Cause they pressing the gas for 20 seconds thing is kinda wierd.

 

Yes its VERY weird. In fact, the engine temp went from "red-lining" to the midway point in 10 seconds. How can the temperature of coolant drop that quickly?? But there were "bubbles" of water/coolant on the interior top of the resorvior this morning, meaning the coolant may have indeed been quite hot and "bubbling" over in the reservoir yesterday.

 

have you checked your coolant levels.......i had a galant that did that and it was due to not having the proper amounts of coolant in the deal!

 

Are you referring to the level of coolant in the system, or the level of coolant vs. water in the "coolant" mixture??

Like I said in previous posts, I added some coolant, but I thought I had one of those little tubes with the balls that checks the ratio of coolant to water, but I cant find it. Wanna make sure its as close to 50/50 as possible.

I doubt the ratio is the problem thats why I'm in no hurry to do it. My father personally filled the system with 50/50 3 weeks ago when we were fixing my car from the collision. But overheating can cause the water to turn to steam, if I'm correct, and lower the level without any leaking. Does this make sense to anyone??

so let me lay out this theory...car seems to be fine right now because I added some 50/50 this AM. But it was a little low this AM before that. If something ie fan, whatever, is causing it to overheat while idling, isnt it possible that water will evaporate, distorting the ratio and lowering overall liquid levels in the cooling system? So it could basically be a "leak" ie im losing fluid, without a physical "leak." The more I lose, the worse the initial problem is. Make sense to anyone??

 

Ok, here's the story of my day.

drove car to work after adding coolant this AM. Idles fine, no overheat. Let it idle w/o shutting it off after I got to work...no overheat. Same thing at lunch. Drove to buy food, left it running while in chinese food joint, let it run a while in parking lot back at work...no overheat, no loss of coolant.

Drove car home tonight. Go to park, same thing as last 2 nights. I parallel parked and instead of turning the car off, sat in it and let it idle for 2 minutes. Sure enough, temp gauge starts to go shooting up again. At this point I ran a series of tests.

I ran the defroster: nothing. Engine temp remained near redline.

I ran the AC: nothing, temp remained near redline.

Then, in park, I rev'd the engine to about 3000 rpm. No less than 5 seconds later, the temp shot right down.

So this presents 3 questions:

A. why only at night? Why didnt it do this this AM or at lunch? In fact, it was the same the last 2 days! Only when I get home from work does this happen. FYI, takes about same amount of time to get to and from work, so its not like the car is running longer or anything.

B. Why does accelerating the engine make the temp go DOWN? Does this triggger the fan to work properly while nothing else is triggering it?

C. OR am I losing coolant somehow, without a leak, and thats explaining why it only did it tonight and not earlier today.

Please help! I am lost on this one!

 

Trip on that

I have the same exact problem with my 2000 ZX3 overheating. I swear I have been lurking on this forum for ever trying to find a thread that describes this EXACT problem.

My car will overheat right after I get off the freeway and sit at a light for a minute. It will also do it in the drive through - basically anywhere where I go from a steady 3k for a while to an idle. It does not do it all the time and my issue is not limited to nitghtime driving - it happens at all times.I have done it all too - I have checked my temp sensor on the fan - fine. Coolant - fine. Thermostat - replaced but not because of this issues so theoretically it could be a shitty sticking thermostat.
But just like you I can rev the engine and the temp will go back to normal. So funkin' frustrating especially in Los Angeles traffic. It gets me on pins and needles to be in 8 lanes of bumper to bumper traffic with the thought that your radiator hose or coolant expansion tank is going to explode under the hood. The girlfriend is convinced the focus is just as big a problem as my 1960 ragtop bug. Anyway...

What I have been rationalizing is that the water pump does not pump enough water/coolant at idle so the shit warms up like crazy in the block...then that hot coolant hits the gauge sensor and spikes the temp. Once we rev it up a bit the pump pumps the hot coolant out of the block and gets replacement coolant from the radiator coil so that is why it cools down so fast. Not all the coolant is hot just what is trickling through all the galley's in the focus block. I dont know about any of this in the factual sense its just my gears turning - I have no idea what the flow of the water pump is at Idle so I am probably terribly wrong - but that is all I can think of because seriously everything else on my ride is tip-top.

Your idea of hot coolant evaporating to the point that it goofs your coolant to water ratio makes sense but I cannot see it happening to the point that you would hurt your engine. Your overflow tank cap is not going to let any vapor out unless you have a real shitty cap. And if it does you would probably see a bit of coolant around you engine bay or maybe the firewall would be wet???


I will be following your posts so please keep us posted if and when you get it all figured out.

 

I have the same exact problem with my 2000 ZX3 overheating. I swear I have been lurking on this forum for ever trying to find a thread that describes this EXACT problem.

My car will overheat right after I get off the freeway and sit at a light for a minute. It will also do it in the drive through - basically anywhere where I go from a steady 3k for a while to an idle. It does not do it all the time and my issue is not limited to nitghtime driving - it happens at all times.I have done it all too - I have checked my temp sensor on the fan - fine. Coolant - fine. Thermostat - replaced but not because of this issues so theoretically it could be a shitty sticking thermostat.
But just like you I can rev the engine and the temp will go back to normal. So funkin' frustrating especially in Los Angeles traffic. It gets me on pins and needles to be in 8 lanes of bumper to bumper traffic with the thought that your radiator hose or coolant expansion tank is going to explode under the hood. The girlfriend is convinced the focus is just as big a problem as my 1960 ragtop bug. Anyway...

What I have been rationalizing is that the water pump does not pump enough water/coolant at idle so the shit warms up like crazy in the block...then that hot coolant hits the gauge sensor and spikes the temp. Once we rev it up a bit the pump pumps the hot coolant out of the block and gets replacement coolant from the radiator coil so that is why it cools down so fast. Not all the coolant is hot just what is trickling through all the galley's in the focus block. I dont know about any of this in the factual sense its just my gears turning - I have no idea what the flow of the water pump is at Idle so I am probably terribly wrong - but that is all I can think of because seriously everything else on my ride is tip-top.

Your idea of hot coolant evaporating to the point that it goofs your coolant to water ratio makes sense but I cannot see it happening to the point that you would hurt your engine. Your overflow tank cap is not going to let any vapor out unless you have a real shitty cap. And if it does you would probably see a bit of coolant around you engine bay or maybe the firewall would be wet???


I will be following your posts so please keep us posted if and when you get it all figured out.

Dude congrats! I didnt think it was possible for anyone else to have a problem this weird. This is a chance for a real Focus EXPERT to shine here [???] Somebody come up big and help us out!!!

Your water pump theory makes sense if you think about it logically. Now riddle me this, I just replaced the timing belt, and had a tune up. I'm idling VERY low right now. So your theory makes even MORE sense b/c of that. The low idle means coolant is definitely sitting in the block longer. Plus at work today my reservoir was really full but tonight its low again. I have no leak, so its either evaporating cuz of heat (unlikely) OR sitting in the block and radiator b/c of low idle.

But the strangeness here: Why just at night? I mean why didnt it do the same thing in the parking lot at work today? Was the bit of coolant I added this AM enough to delay the overheat to tonight? I mean if the theory about the water pump IS true, then when I sat and let it idle at work today before goin in (for about 10 min, same as getting home from work) the same thing shouldve happened but it didnt.

heeeeeeeeeeeeeeelp---could a faulty tuneup, or even WORSE, faulty installation of the timing belt cause the water pump to act up when idling?? This could be a critical question. Any thoughts???

 

Have you checked the thermostat?

 

Where is the thermostat located on my engine?

I have an 02 ZTS, so its the 2.0 DOHC zetec.

 

A weak water pump will show up with this symptom...you guessed it...overheating at idle.
When you rev the engine up, the pump turns faster, sending more water through the radiator which in turn cools the engine back down.

 

OK heres the latest. BTW, thanks to EVERYONE for helpin out and chipping in here.

Today on my lunch, I let the car idle for ten minutes. Just enough to get it running hot. It did NOT overheat.

But this is what I did notice with some detective work. Neither of the 2 AC fans are running. They didnt run at startup and didnt run even when the car got hot. I turned on the AC and they still didnt run. AC didnt work but its also out of C2 or whatever the system uses. I had to empty it out when repairing the vehicle from the collision and havent worried about filling it again. So AC didnt work, but the key is THE FANS didnt run when I turned the AC on either.

I mean whats the deal with those 2 fans? Shouldnt they be "tripped" and start running when you turn the AC on OR when the car gets hot? Or even the defroster? Doesnt that make one of the fans run?

Anyhow, so it looks like its narrowed down (somewhat) now to the fans not turning. so where do I go from here?? I have limited knowledge. Granted this STILL doesnt explain the car cooling down when reving the engine either. But anyhow, I checked the fuse panel under the hood first b/c they are run by 2 fuses I believe. One looked blown, but I couldnt get it out. How do you pull the fuses out?? I have no nails I think I need a butter knife or flathead screwdriver or something.

Anyhow, if the fuses are blown, obviously I will replace and see what happens. If they are not, where do I turn next?

Thermal sending unit? the little plugs and wire on top of the fan shroud?

Now as far as the thermostat, still a prime suspect here, wouldnt a faulty thermostat cause the fans NOT to come on as well? Someone please explain in dummy language how the thermal monitoring system works in cars. Because its not making sense to me. If the thermostat is broken, it could cause the fans not to come one. But the thermostat seems to be working FINE because it tells me when the car is overheating doesnt it?? HELPPP!!!!

And as far as revving the engine and the car temp going down, it seems to me the water pump or the thermostat are the ONLY TWO things that could cause that. But on the same token, those 2 things might not be responsible for the overheat in the first place. See what I"m saying?? For instance, the fan not running could be causing the overheat to begin with. But a faulty water pump explains the cooling down when pressing the gas. The water pump is obviously not COMPLETELY given out b/c the car doesnt overheat when running normally. But the weak water pump could be the SOLE problem here. I'm thinking this because it explains BOTH.

I really need you guys. My dad is my go-to guy. He rebuilt my car but he's stubborn and old fashioned. I explained to him "the waterpump could be weak, causing the engine to cool when reving it, right?" and he goes "NO, the waterpump either spins or it doesnt." I dont know as much as hi m but I beg to differ. Maybe it operates fine when reving the engine but is NOT working correctly at idle?? He says "impossibe!" I dunno about that, and I actually disagree despite him being more knowledgeable about cars than me.

 

Did anyone check their lower radiator hose? If the hose is old, the suction of the water pump could be collapsing the hose preventing to coolant from flowing properly.

 

A point of interest that might help you is how the temperature gauge works in the Focus. It is more of a 'mechanical idiot light' than a true gauge.

It shows a gradually increasing reading as the engine warms up, then stops in the middle. With a scan tool you can watch the ECT sensor (which actually reads the direct temps and is where the computer gets its'information) climb up to the point of fan actuation....and the 'gauge' hasn't moved from the middle position! Fans come on and go off and the 'gauge' will not show the varying temperature.

Only when the temps reach a dangerously high reading will the 'gauge' move over to or near the red zone. It goes quickly and the difference in a degree or two means it will show normal or hot.

Your fans are not working. You know this already. When you stop moving, the water starts getting hotter. How much hotter depends on the outside temps, whether a breeze is blowing air through the radiator (even though you aren't moving), how long you idle and how hot the engine was when you stopped.

Revving the engine spins the water pump faster which pushes more coolant through the radiator which WILL drop the temp a few degrees...which trips the 'gauge' back down to the normal reading. Confusing? Yes. It would have been SO much simpler if Ford had made the 'gauge' an actual gauge.

But, I worked at a dealership back in the early '90's and we had people coming in pretty often complaining about low oil pressures and/or their temperatures being high. In both cases, the gauges were reading normally....oil pressure drops with warm oil at idle. And, the water temp will vary depending on the fan operation cycle.

Ford finally gave up trying to deal with less than knowledgeable owners and made the oil pressure gauges in to 'mechanical idiot lights' that have a 5lb switch that, when closed, moves the 'gauge' to slightly above midway and there it stays regardless of what is happening to the OP. Only if the pressure falls below 5lbs will the 'gauge' drop. Not very good.

The SVTF has 'oil pressure and temp gauges' that have no actual senders...other than the aforementioned 5lb switch. The ECU sends the messages to the 'gauges' that it thinks they should read by inferring a bunch of other engine information. I have mechanical meters for my car because I cannot stand any more not knowing what is actually going on when I am in it.

Sorry for the book, and I hope this helps you.

 

"Anyhow, if the fuses are blown, obviously I will replace and see what happens. If they are not, where do I turn next?"

If you dont hear the fans "click" on, then you need a new relay.. but you should hard wire your fans to make shure there working right.

-Eric

 

Ok checked fuses today, both are fine. But when I started the engine, I'm now seeing a coolant leak. Its almost impossible to tell where exactly its coming from, but I'm going to insert some pics of underneath the car. Every car has its dripdown pattern...For instance, in my old blazer, I had a leak in a hose leading into the heater core. Thats under the glove compartment pretty much. Well the drip was towards the middle (front to back) of the car, ie NOWHERE near the leak's origin. I'm sure hoping someone has seen coolant coming from this area before and can give me a head start on where the leak is originating from. I'm sure all of you know this, but these pics are from under front left corner (driver's side) of the car, looking up towards the engine...one looking up at the axle.

And I guess the fans werent causing the overheat afterall, it was low coolant from this leak...that explains why it only overheated the couple days BEFORE i added a little coolant. And also explains why it hasnt overheated since, despite fans not working still, after I added a bit more coolant yesterday. Anyway, I'm either attaching pics or putting them right into this message.

PLEASE HELP! I'm thinking that thermostat housing or my water pump....thoughts?

Edit to add: FYI, first picture, there is a drop of coolant visible on the left, but its leaking mostly from whatever is captured in the right side of the image. Cant really see it, but theres a nice little puddle under there. The drip is hitting the ground about 2 feet inside the front left (driver's side) wheel. The 3rd pic prolly captures the area the best. Pretty steady drip coming from there. AND this I find to be quite interesting. It was NOT leaking when I shut it off last night, and was dripping this morning!!! Car had not been run in almost 18 hours and it was actually DRIPPING when I went to go check the fuses this AM before I turned the key

 

From the area it looks like your housing.

 

ok well my idea was not a leak, but u need to get that fixed as well, it sounds like when u step on the gas it speeds up the waterpump so that is why it was cooling down. i did some research and i found out the fan motors r known for seizing up, so u should check that out. the thermostat housing is not that hard to do. just follow the radiator hose on the pass side of the car and follow it to the housing under the coil pack and it is just 3-4 bolts and i think 3 hoses.

 

I'm gonna deal with the fans after I get this leak fixed.

My guess is this has been a slow intermittent leak that caused my coolant level to be JUST LOW enough to raise the sensitive temp gauge while idling. If anyone has PICS of the housing area, that'd be great. If not, I'll simply search the boards here, I'm sure someone has posted pics or details on how to get at the housing unit.

Thanks again fellas.

 

3 bolts, temp guage wires and 3 hoses and your housing is off.

 

Hey guys,

I searched the "how to's" here and found everything I need and MORE for replacing this thermostat housing unit. I'm losing about a quart of coolant per drive to work each way, so I gotta get this done ASAP.

Is there a "how to" on the water pump? I dont recall seeing it...

But quick question w/o getting into too much detail, does the engine need to be supported to replace the water pump? My pops just did the timing belt and engine needed support just for that. Also, does timing belt have to come off again just to get to the water pump? Any estimates on how tough a job that would be?

Thanks again everyone.

 

i dont think it is a water pump issue, i think it is a fan issue. before you spend 2 hrs replacing the waterpump check the fans

 

But first I have a coolant leak that needs to be dealt with. I appreciate the help, I am going to fix the fans, I've only gotten as far as checking the fuses. How about relays? How can I check those? Also, as far as the fans, what else could be wrong with them after the fuses/relays?

But coolant is leaking from either the thermostat housing unit or the water pump. You're saying its only a 2 hour job for the water pump though...obviously you have done this before or know SOMETHING about it. Does the engine need to be supported?

 

haha next question...

is there a gasket or seal that goes on when you replace the thermostat housing unit?

 

Yes theres a gasket on the housing. I had a leak there and i had to replace the housing cuz theres a inter lip that the gasket sits between and it was deterorated. easy to do tho just 3bolts, the hardest part is disconecting the hoses beacuse the clamps are P.O.S. But i have the same problem with my car overheating when parked. I got my fans checked and they were working. I was told by ford that my water pump is going out. So iam going to order a high flow water pump and it should be fixed. ill keep u poasted.

 

The gasket is an o-ring.

 

I just posted on another thread the latest on my problem, or the one my mechanic seems to believe it is: a water pump impeller. Not same, but similar issues as yours.. drive for a while, no problem. Once problem starts, it'll cool a bit down when i press on the gas pedal, get hotter when it idles (and also hot at high speeds.) Mechanic says impeller is cheap and tends to wear out and he feels problem is that after running diagnostics on fan.

 

Interesting. Never heard of that happening.

 

That's not our housing. . . . .You can re-use the housing if there are no cracks, just slip a new o-ring on in the slot.

 

that was the housing autozone tried to give me after i ordered it. i think i am going to have to go to ford for the actual, cause that is the one that napa tried giving me too. it sucks cause ford wants like 40 bucks for theres

 

Yea, I havent even taken mine out yet, but I can tell that thing would have a helluva time fitting, let alone lasting, in our engines. its a POS.

But get this: the north jersey dealers that over charge you for labor hours, ie 2 hours for a 30 minute job, sell the part for $56. The South Jersey dealer, who said book time on the job was 45 minutes, and was HONEST, sells the same part for $115.

Moral of the story? You cant win for losing. They all have their "methods" of making money. My best bet is probably to buy the part up here where its not marked up as high, take it home just in case I need it, do the work myself (not gonna drive it 140 miles with a leak just to pay someone to do the work, no matter how cheap, LOL) and then return the part when I come back if its just the O-ring as I suspect. Make sense??

And talk about a "quirky" leak, I just drove 10 miles to go pick up lunch, ran the car for about 40 minutes total cuz I had to run to staples too, and didnt leak one drop. BUT when I opened the cap to top it off this AM, it was leaking like a flood, without the engine even running! Does this have to do with pressure? ie, when you open the fill cap, it causes it to leak more?

 

40 bucks for the t-stat housing????

 

yeah just go there and say u r from pep boys or autozone, just call first, and bring cash, they wont know and they will give u the commercial discount. i used to work for pep boys and i have like 5 pep coats so i just walk in and that automatically assume i work there.