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KrisQ 07-09-2012 03:15 PM

Changed almost everything but car still over heats!
Hi guys thought I'd post here to get ideas on what might be causing
my girlfriends car to over heat.

First off we live in Las Vegas and avg temperature is 110 this week.
Car is 2001 Focus SE.
Temp guage goes past 2/3 and near red and back down.

Things I've changed:
- Thermostat and whole plastic housing.
- Upper and lower hoses.
- Coolant flush.
- Water pump.
- Checked radiator fans and resistor are OK.
- Coolant reservoir and cap seems to be holding pressure. I might change this next.
- Transmission fluid and filter.
- Oil and filter.
- Sparks plugs.
- Air Filter

Any suggestions on what could be the problem will be appreciated.
Things I might change next:
- Radiator fans
- Coolant reservoir and cap.

Mike_Mac 07-09-2012 03:36 PM

do both the upper and lower rad hoses get hot?

sailor 07-09-2012 03:44 PM

Sounds like the "normal" readings you'd see if the high speed fan circuit is working, and the low speed is not.

As the engine warms up, the thermostat opens enough to maintain temperature at the correct point - as long as the car is moving & the outside temp is reasonable this gives all the cooling needed & the gauge stays near the bottom of the "normal" range.

When it's warmer out, or the car isn't moving enough for air flow through the radiator, the "low speed" fan circuit kicks in - cooling the radiator 7 hence the coolant so the thermostat can do it's job (it's full open at this point) and the needle can go near the high mark on the gauge when this is happening.

High speed fan operation (when needed) usually doesn't kick in until the gauge is at or near the red zone, and if the low speed circuit isn't working temps will "spike" into the red zone B4 the high speed fan operation can "catch" the rapid heating & bring the temp back down....

You didn't happen to mention HOW you checked the low speed fan operation, OR whether this is a new symptom from a car you've owned - OR a worrisome gauge reading on a newly purchased vehicle.

High & low run off separate relays, so if you AREN'T getting low speed operation that might be another area to check...


KrisQ 07-09-2012 04:26 PM


Originally Posted by Mike_Mac (Post 4250433)
do both the upper and lower rad hoses get hot?

Thanks for the reply! I'll check this tomorow and report back.

KrisQ 07-09-2012 04:32 PM

Thanks for the reply!

The only test I did on the fan is I waited till they turned on when the car got hot. Another fan test was I turned the ac on and they turned on. Im not very familiar with the fan operations how do I got about checking the high and low?

Also I was vague about the problem sorry. The fluctuating temp guage only happens during peaks heat hours of the day (like on her way to work at 3pm). During mornings and nights when outside temperature is below 100 the gauge stays steady at normal.

Another thing I failed to ask is about the heat shield that was mounted on the exhaust manifold. The screws cracked and it fell off and was never replaced so the manifold is exposed. Could this be a possible reason? The engine bay temp seems higher.

Thanks again.

sailor 07-09-2012 05:10 PM

Missing exhaust heat shield can be a culprit in "helping" the resistor pack go bad, due to excessive heat.

A/C on "max" should give you high speed fan operation - MUCH "noisier" than low speed operation as a reference point. SO, if you don't see/hear them come on quieter than that (like when idling in the drive on a warm day to test them) you aren't getting low speed operation.

In "normal" operation the gauge will go at LEAST as close to red B4 fans start cooling it as it is close to cold in normal operation when the thermostat opens. this gives a WIDE swing on the gauge that can be scary the first time you notice it. IF the low speed isn't working, it'll probably go into the red B4 the high speed cools it down, since the temp is climbing quicker than normal at that point.

In other words, the first description of the gauge readings MAY be normal - but you SHOULD confirm low-speed fan operation for peace of mind....


autolite 07-09-2012 05:22 PM

On my old Mustang the radiators just get plugged.I went thru this flushed it no change had a professional flush no change.Swapped rad good to go.Mostly mine would get hot on the freeway city driving it would run cooler.

focus202 07-09-2012 06:21 PM

It looks like you replaced everything but engine temperature sensor, see maybe that's bad. since it goes 2/3 and then back I think it means that it start the fans later than normal, which I think that it might be the temperature sensor.

KrisQ 07-10-2012 05:33 AM

Thank you all for the suggestions! Special thanks to sailor.

I though about the fact that the heat shield is missing but I could not believe that the engine bay temp can be that much hotter without the heat shield so I removed the exhaust manifold and found a small crack. The crack is located on the first pipe on a weld seam.

I'll see tomorrow if I can have it welded or if I have to find a replacement.

I'll update after this part is fixed.

Thanks to you all again.

KrisQ 07-10-2012 05:36 AM


I'll keep the temp sensor in mind. I might replace it tomorrow just to cross it out.


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