Ford Focus Radiator Issues Has Me Hot Under The Collar

This past Saturday afternoon I’m out driving on the highway when the temperature gauge on dash maxes-out and the overheat warning light comes on. I get off at the next exit and stop at the nearest repair shop. (Which happened to be not too far from the exit.) During these moments of driving the car is not behaving as if it were overheating. No steam/vapor coming from the engine, it’s performing okay, A/C runs cold, running heater on full-blast seems to do nothing to ease the gauge and the temperature in the engine bay feels about “normal.”

So, since this is a Saturday at almost 5PM most of the repair shops are closing (it’s a known fact cars don’t break down past 5 o’clock on Saturdays.) So they say the’ll look at it on Sunday.

I get a call on Sunday and I’m told that as near as they can tell the car is not overheating, the overheat light or check-engine lights weren’t coming on and the car is behaving normally. The thermostat is “gunked up” and they recommend new coolant or a coolant flush." I just opt for new coolant, forgoing the flush, as I didn’t really have the funds for it, an additional $100 or so. They say there are no codes in the system.

They do it and end up having to keep the car overnight so that the… air bubbles will work out of it? (?!)

I pick it up this past Monday evening and on the drive home the temp-gauge does as it was doing when this process began. It started creeping “hotter and hotter” meanwhile the car is behaving otherwise fine. (No overheat light this time.) Get home, open the hood, no vapor, no excess heat. Nothing.

Call the shop, they claim they took the car out to test it, on the highway, everything and experienced no troubles with it but tell me to go ahead and bring it in on Tuesday. So, I do.

They spend quite a bit of time running it, hooking it up to a diagnostic machine, etc. While the temp-gauge is sort of “floating around” between normal and “hot” it doesn’t reach an “overheat” and the diagnostic machine registers normal temperatures. This time they find a code in the system, though the check-engine light has never come on. They recommend, again, the coolant flush so I go ahead and do it (they give me a discount), and drive the car home, again the temp-gauge “floats” around the dial, never quite getting to “overheating.”

I drive to work just fine Thursday (today) morning with no real trouble with the gauge. (Though, FWIW, I had to tap on the dash to get the dash-light on that side of the console to come on.) This brings us to Thursday afternoon.

I make a couple of errands and as I’m stopped at a pharmacy drive-thru the temp-gauge is “floating.” Driving home on the highway it reaches “overheating”, turning the light on (again, car is not behaving in an overheating manner. A/C still cold, running heat doesn’t ease gauge, no vapor from engine compartment.) When I pull in my parking spot the A/C and the car starts to “stall” some and NOW the check-engine light comes on. I shut the car off and I see vapors coming from under the hood.

I open the hood and the engine is covered in the anti-freeze/coolant and the coolant reservoir is empty. The various hoses and such that are clipped on to parts of the front engine cowling are loose (the plastic screw/“snaps” came out of their holes) and pushing on the upper-radiator some and it seems awfully loose. (Like the upper mounts aren’t properly seated or something.)

Call the shop ask them what they are doing to me, they say they’ll have another look at it and pay for the tow to get the car back to their shop. Awaiting word on what is going on, likely sometime tomorrow.

All of this strikes me as very, very odd and all seems to pile up quickly from taking it to this shop. With a replaced thermostat and flushed coolant I have a hard time understanding how the engine could genuinely overheat. All of the hoses and such seemed fine, and running the engine for a while at the shop the other day generated no problems to the techs working on the car. Yet, they’re the only ones who have messed with it. Assumptions on their part Tuesday afternoon were something to do with the water pump (replaced at 100,000 miles with timing belt. Car is now at 145,000 miles.) Or a faulty temperature sensor (or what passes for it on the car) sending false readings to the gauge.

So what’s everyone’s thoughts?

Car is a 2000 Ford Focus ZTS with a 4-Cyl, 16V, 2.0 Liter engine. It has 145,000 miles on it, timing belt and water-pump were replaced at 100,000 miles have had regular oil-changes on (more or less) every 5,000 miles or so. I will admit to not getting coolant changes/flushes as often as one should but the car never really had an overheating issues or problems starting in the winter.

Does the heater blow warm air with the engine at idle with the engine warmed up? If the answer to the question is no, check the coolant level with the engine cold and post back.

Don’t have the car with me right now, had it towed back to the shop. But the heater blew hot whenever I turned it on (driving to try and take some burden off the heat, and at idle when stopped.) As for the coolant level, last I had it coolant level in the tank was pretty much nothing considering it was sitting allover the engine bay.

You’re describing he early signs of a head gasket failure.

That is until the later signs of a head gasket failure.


if you think your car is overheating, turn the ac off right away…, and the car.


“Call the shop ask them what they are doing to me”

They are trying to solve your problem in a methodical way. YOU are the one ignoring your temperature gauge and allowing it to overheat. It was a probable head gasket problem. Now it may be a warped head and who knows what else problem.

If you’re expecting this shop to fix the problem I fear you’re not learning from your experiences.
If you’re expecting this shop to fix it at no additional charge, I fear you’re altering reality.
And any mechanic that believes that he/she has properly verified/disproven an overheating problem by idleing the engine must have played hookie a lot in school… an engine creates a lot more heat when driving than it does at idle. It is possible to find a problem at idle, but it is not possible to diagnose the absence of a problem at idle.

Diagnosing overheating problems is not rocket science. Any competent shop can diagnose and correct the problem… but it will cost you more than $100. They’ll probably test the system for leaks under pressure, check the coolant for the existence of hydrocarbons, perform a “pressure leakdown test” if they suspect a headgasket leak, test the radiator for flow and “map” the radiator with an infrared thermometer for evidence of blockages, check the pump for flow, test or replace the thermostat, test or replace the radiator cap, and maybe even check the radiator hoses for evidence of cracks or failure (hoses’ inner liners can close up). If your Focus uses the radiator to cool both the engine and the tranny fluids, they may even check for evidence of passage between the two sections of the radiator.

Somewhere in all of this testing the real source of the problem will pop up. But it will cost you more than $100, so be prepared. Unfortunately, your only other option is to let the current shop continue to do nothing meaningful.

All I have to add is that if they test for a head gasket issue and it comes up negative, I would be thinking of a clogged up radiator. Especially if there was gunk in the system. Many years and miles of bugs in the front and gunk flowing through the radiator.

They are trying to solve your problem in a methodical way. YOU are the one ignoring your temperature gauge and allowing it to overheat. <<

I took the car in the first time the gauge went into the red, where they said they couldn’t duplicate the problem, find any trouble codes in the system and recommended the t-stat change. After changing the t-stat they said the temp-gauge was normal when they “test drove” the car, giving it back to me. I drive it and the gauge acts up. Take back to them, the gauge acts wonky while they run the car, coolant flush. Drive it home, not too much of a temp problems, day later coolant all over the engine after another overheat warning and stopping. If it’s a head-gasket or something along those lines I would suspect a competent shop would have found this during the FIRST time I drove it in, especially if they “test drove” the car after replacing the T-Stat.

“…I would suspect a competent shop would have found this during the FIRST time I drove it in…”

This and similar web sites are packed with high mileage vehicles with intermittent overheating problems. I’ll guess the majority try replacing thermostats, water pumps, radiator caps, and end up being blown head gaskets, i.e., the most expensive to fix ($1000 - $1500). If you feel the shop lied about not experiencing what you did, never go back there. (You balked at a $100 flush, remember.)

So, here’s the latest. The shop said one of the hoses busted and was full of holes, causing the coolant leak. They replaced the hoses, for free, but said the thermostat gauge was still acting up. Being done with them I took the car to my dealer, where I normally get the car serviced and have never had a real problem with them. Enroute, sure enough, the gauge reached overheating, being further away from the dealer than I was willing to drive I pulled over and got a tow.

Dealer gave it a look-over and concluded the radiator was plugged up. I need a new radiator. Again, I fully admit to not being 100% on top of keeping the coolant clean and everything but the car never had any over-heating/freezing problems so I just “lost track of it.” All on me, I’ll take the damage to the radiator.

Now I have questions:

  1. Did I really need that new thermostat? If these problems all stemmed from needing a new radiator, what did the thermostat have to do with any of this? The guys at the original shop said the thermostat was a little gunky, but that didn’t really seem to indicate this was a problem. More of a potential one. But, ultimately, didn’t solve the original problem.

  2. How do you flush a coolant system with a plugged radiator?

“concluded the radiator was plugged up”

I have a few concerns with this . . .

Was the radiator plugged up, because the coolant hadn’t been serviced in a timely manner?

Or was it plugged up with mocha frappuccino, meaning you probably have a blown head gasket?

The head gasket didn’t seem to them to be a likely concern since the car isn’t exhibiting any other signs of a blown head gasket. No smoke from tailpipe, oil is normal, car isn’t losing coolant (other than when the hose(s) burst.

I’m not really sure what they meant by wanting to “flush” the cooling system. Usually what I do as part of a cooling system maintenance is drain all the old coolant out, replace the thermostat with a new one if it is looking corroded at all, and replace with fresh coolant and do an air-bleed procedure. Ever car is different of course, but that’s what I do on my Corolla. As part of this process, if the radiator is getting plugged I’ll usually notice that as, first I can look inside the radiator and see if the holes are clear, and second, it will take longer than normal to fill a clogged radiator, as the coolant takes more time to work its way past the clogged passages.

As part of this I’ll do a visual inspection for hoses on the fritz and I’ll use a mechanics stethoscope to listen to the water pump bearings. Edit: I can also see how much coolant flow is coming into the radiator once the thermostat opens, giving me a judge of the water pump efficiency.

It’s not unusual for a thermostat to be a cause of this kind of problem, so it’s reasonable I think they suggested this. I had to replace the thermostat on my Corolla last year because it was corroded and wouldn’t close completely, causing the coolant temp to be too low. It’s hard to tell just by looking at one if it is working correctly though. You’d have to do a water bath test. Thermostat replacement usually isn’t a very expensive procedure and is the more cost-effective method usually.

If I had been in your situation and the shop didn’t diagnose and fix the problem straight away on the first attempt, I’d probably have taken the car to my local radiator shop. They do this kind of job 8 hours a day, 5 days a week.

That’s sort of what I thought. I would think when they did the flush (drain the coolant, run water through the system until clean, refill with new coolant) the radiator being plugged would have presented itself. Only reason why I took it back to them the second time is that they were the last ones to mess with the car so, it seemed to me, they didn’t do something right and need to fix their mistake.

I’ll own up to the coolant being cruddy as it had been a while since I changed it (but the car was staying cool in the summer and starting fine in the winter.) But if the radiator was clogged I would think that problem would have presented itself during any initial test that led to them suggesting the thermostat. But most certainly should have found it when flushing the system.


Here’s another wild thought . . .

I’ve encountered faulty aftermarket thermostats which actually CAUSED overheating

A few years ago, I replaced my thermostat . . . which was working fine . . . because it was several years old

Immediately afterward, the coolant temperature skyrocketed

Even after purging all the air, it didn’t help

I brought it back to the store, and they gave me another one, which worked perfectly.

But they insisted I must be smoking crack, because “they don’t stock bad parts”

if my car temp gets to the red zone I stop. it s cheaper to call a tow truck than it is to deal with the major problems overheating can cause.

that extra mile can be expensive


When a coolant exchange is performed, the upper radiator hose is removed from the radiator and the exchange machine is connected to the radiator and the upper radiator hose.

The machine is then turned on and it forces fresh coolant into the radiator, circulates thru the entire cooling system and the old coolant is collected in the machine.

The machine doesn’t produce more pressure than the cooling system operating pressure otherwise it would blow the pressure cap open.

You can also check for cooling system leaks as machine exchanges the coolant.


One comment. As mentioned above, the content of your conversations with the shop may have had something to do with your subsequent experience, so consider that before placing too much blame on the shop.

For example, a couple months ago I bought some construction material from a contractor supply place – not the local home store in other words – and I told the rep there (who was an expert on this subject) I wanted to save money on the job where I could. The material he supplied to me wasn’t the same as if I had said I wanted to make the job as easy to do as possible. So when the crew came to install the material, they complained the supply place had made a mistake. But in fact the supply place was just doing what I asked them, trying to save me some money.