I have a 2001 Ford Focus ZX3 with about 120k miles on it. It recently started having issues overheating, and I, as well as my mechanic, have been having a very difficult time trying to find the problem.

About two months ago I was finishing up a 5 hour drive home. Most of the drive was on the high way, but I live in a city, and as I got closer to my apartment the traffic really slowed down. I noticed in the stop and go traffic the engine temp gauge was creeping up towards red. I immediately turned the heat on high and the fan on full blast, which brought the engine temp down right to the middle of the gauge (I'll call this position "normal"). The check engine light never came on and the engine temp seemed to be under control with the heat turn on, so I finished the drive home. I noticed that when the car was in motion, the engine temp went to normal. It only went up when the car was stopped.

When I got home I popped the hood and noticed the coolant level was low; almost to the low mark on the coolant tank. After the car cooled down I added premixed coolant up to the fill line on the tank. Last year I had a coolant leak, so I had extra coolant around. One of the intake tubes had cracked and caused a slow leak. It was replaced and I didn't have any problems until recently. A few days after I added the coolant I noticed the overheating again, and when I checked the coolant level it was back down. I topped it off again and took it in to the shop. I didn't see a leak when I looked under the hood and there were no signs of coolant on the ground where I park my car.

The mechanic said I needed to get my temp sensor replaced and the water outlet was leaking. I had him replace both. Things seemed fine when I got my car back, but about a week later I went on another several hour trip that ended in stop and go traffic. The engine temp starting going up again, and yet again this only happened when the car was stopped or going very slow. I turned the heat on, the temp went to normal, and I immediately took it back to the same shop.

A few days later I get a call from the mechanic. He says he tried to flush my radiator and couldn't get it to clear out. His theory was that my radiator was clogged up; the water pump could circulate coolant when I was pushing on the gas, but couldn't do so when the car was at rest. He tried to flush it 3 times, couldn't get it to clear, and then put a chemical flush in the system. He told me to drive the car for a few days, primarily long drives on the highway, and then bring it back. He told me the highway miles would help circulate the chemical flush and clear out the radiator. I drove about 6 hours on the highway over Thanksgiving weekend visiting my family, and when I got home I took it back to the mechanic.

He flushed the system and put new coolant in. He told me the water pump was running fine now. I picked the car up a few days ago, and had another long drive today. Coming back from about an hour drive I get into stop and go traffic, and the engine temp starts moving up, yet again. I turned on the heat, the temp went to normal, and I drove the car home.

I'm at a loss as to what's going on. This is the first time I've used this mechanic, but he has seemed very honest so far. He didn't charge me for any of the extra work after I brought my car back in. But at the same time he didn't find the cause of the problem. The check engine light has never come on, even when the engine temp has risen very close to the red zone.

Since this started two other minor things happened with my car. I think they are unrelated, but I'll put them in here for full disclosure. My left headlight went out. I haven't had time to replace it. Additionally, my right turn signal now blinks twice as fast as my left. I can hear and see the difference when it's on.

Does anyone have any suggestions as to what is going on with my car?

 

Let's hope we get a few responses on this.
Do you recall hearing the cooling fans run at any time when the temp went past the normal mark? I believe that could be the one thing that may have been overlooked.
A quick check would be to turn the A/C on , the fans should come on at the same time.
If they do, then I would suspect the sensor that controls them or possibly the relay or the fuse that supplies the system.
The headlight is probably just a burned out bulb. The next thing you can try is to turn the right signal on and check the front and rear to see which one isn't blinking. Usually the bulb has become open and would require replacement.

 

I would never claim to have the knowledge of hanky, but I have run into a few head scratchers like this in my day.

My first check would be the fan as hanky stated, though I would go about it differently (no two people are the same, neither is their approach to a situation). While turning on the A/C will tell you if the fan motor and relay are working, it will not tell you if the temperature switch is telling it to turn on. My first choice would be to bring the car to operating temperature without the A/C (normally 190 – 210 degrees). If the fan comes on you know the fan, relay, fuse, switch, and ECM are working correctly, if not you have narrowed your search.

Another thing to check is airflow. Look at the front of your radiator; are there bugs, leaves, dirt, and/or other items that could restrict airflow through the fins of the radiator? This is common in my area (backwoods country boy LOL) and an easy fix. If this is the problem you will need to clean that out, but what blows in from the front should be blown back out the front. When I do this, I disconnect the negative battery cable and remove the coolant fan assembly. If I remember correctly on your car it is a pretty straight forward process. A few clips and 2 plugs and it lifts right out. I have taken a garden hose to ½” cpvc fitting glued it to a 3 foot piece of cpvc pipe and glued a cap on the other end, then I drilled 1/16” holes every 3 or 4 inches up from the bottom for the first 18 inches. Works great to get in behind radiators and wash out the fins. Even better keeping the kids happy in the summer.

As the engine warms so does the coolant, and the coolant expands causing a pressure increase in your system. Radiator caps are designed to relive this pressure to prevent gasket and seal failure. If your cap is designed to release pressure at 16lbs but is worn and releasing it at 8lbs, this could also be your problem and reason for coolant loss. Ask your mechanic if he tested your cap.

Something to keep in mind as well is the water pump. Many times you will hear “if your water pump is bad it will leak”. That is incorrect. Engine coolant is moved through the system by a propeller or fins on the water pump. I have seen many times where these fins have corroded off to resemble a saw blade rather than a propeller. In these cases higher RPMs will provide enough movement to cool the car, but lower RPMs will not. This is not likely the case in your situation but something to be aware of.

The aforementioned are just the basics; there are other things to look at once these have been eliminated. Like debris in the engine that could be partially blocking cooling ports. Many times a repeated flush will clear these out.

Question, do you know if a block sealer or stop leak has been used in your car?

I am confident your mechanic is on the right track. While most blockages in the radiator can be cleared with flushing, there are times a radiator replacement is necessary.

As per your lighting issue, I will refer to hanky’s suggestion. A quickly flashing light is indication of a failed bulb, either front or rear.

I hope this information is helpful, best of luck.

 

ModestRick,
Thank you for sharing your experience and knowledge. It is sincerely appreciated and oh, and by the way, I needed all the help I could get ! Have a good one !

 

For the problem with your headlight/turn signal, you have a problem with Splice 121 on the wiring diagram.

 

There has to be a problem with the cooling fans because the cooling fans do not operate at highway speeds because there is more air flow across the radiator at highway speeds.

 

Thanks everyone for all the replies!

I went back and tested the fans again. I had done this a few weeks ago and they were working. Yesterday I started the car, kept it in park, and turned on the air conditioner at full blast. Neither fan turned on this time. I think I may just have had bad luck with the timing of two separate issues that result in the same problem.

I've been looking into fan issues in Focus's and it seems like this is a very common failure. I'm going to take it back in and ask them to check it out. I tried to disconnect the fan unit to check the fan resistor but couldn't get it out on my own. I tried to check the relay as well but no matter how hard I pulled I couldn't get the relay to come out of the power distribution box. I think the relay might be the source of this problem given that neither fan is turning on.

For posterity, here are links to the fuse box diagram and the fan electrical schematic.

http://www.justanswer.com/uploads/Vi...1744_relay.jpg

http://www.justanswer.com/uploads/Vi...014217_svt.jpg

And I checked my lights as well and my right rear light is out! I'll fix that myself once the cooling issue is sorted out.

Thanks everyone for the help an advice! I'll post an update after I take it in. I'm traveling for work so it will be a while before it gets fixed.