Ford Focus Forum, Ford Focus ST Forum, Ford Focus RS Forum - Reply to Topic
Ford Focus Forum
HomeContact UsAbout UsGalleryDiscussion ForumsMarketplace


Go Back   Ford Focus Forum, Ford Focus ST Forum, Ford Focus RS Forum > Ford Focus Tech Discussions > General Technical Chat > Coolant temp sensor!

General Technical Chat This section is for technical discussions relating to general maintenance, electrical issues, engine trouble, and recalls.

Search This Forum | Image Search | Advanced Search    
FocusFest FocusFanatics Merchandise

Thread: Coolant temp sensor! Reply to Thread
Title:
  
Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:
 

Register Now

In order to be able to post messages on the Ford Focus Forum, Ford Focus ST Forum, Ford Focus RS Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
What I Drive
Year, color, and model of your car. Example: 2003 Pitch Black ZX3
Name
Your real name.
City
State
Country
Insurance
Please select your insurance company (Optional)

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Additional Options
Miscellaneous Options

Topic Review (Newest First)
02-14-2015 04:11 PM
Benefit
2005 ZX3 Cylinder Head Temp Sensor

This thread is a bit old, but maybe my experience with this will help someone in the future. My daughter drives a 2005 Focus ZX3 with 175,000 miles. On a zero degree night, she called from school saying the car was overheating, the temp gauge was in the red and the light was on - but she hadn't left the parking lot yet, the car had only been running 2 or 3 minutes. Smart girl for paying attention, being a new driver, and all.

I drove 15 miles to pick her up, checked the radiator and hoses - ice cold - no obvious leaks. I started the car. Within 3 minutes, the dash temp gauge moved all the way into the red and the warning light came on. I checked, the coolant was not frozen. Figuring it was a stuck thermostat or water pump failure, I had it towed to a garage. (Did I mention it was zero?)

Much to my surprise, they called the next day and said that their engine analysis said the cylinder head temp sensor was bad. I didn't 100% believe them, but told them to change it and flush/fill the cooling system, figuring if there was no circulation, they'd find it while draining/filling (and then fix the mechanical problem!)

But, lo and behold. I drove it home, it behaved perfectly after the repair. They were right.

The $350 was a little painful, but I was not looking forward to chasing this down with snow on the ground and a daily high temp of 15 degrees.

In hindsight, it was unlikely that even with no coolant flow, that the engine would completely overheat in 3 minutes at idle on a zero degree night. I didn't try the cabin heater to see if I was getting coolant flow through the heater core. I was too damn cold.

So, moral of the story, these sensors do go bad, they are in the valve cover, and they can fool you into thinking thermostat or water pump problems. The sensor was only $30.00 for the part. Under better conditions, a fairly easy repair.
04-26-2013 04:54 PM
Kodyston
Quote:
Originally Posted by erhodes View Post
Hey guys I desperately need some help. I need to know where exactly the coolant temp sensor on a 2005 ford focus ZX5 with the 2.0L duratec is. I was sold a coolant temp sensor today in an effort to solve an issue ive been experiencing. Ford parts calls the sensor in the middle of the head in between the 2 and 3 coils a manifold temp sensor-not a cylinder head temp sensor. but they do not call out a coolant temp sensor. I cannot find any info on this anywhere on the web. Everyone says "they don't have an ECT, they have cylinder head temp sensors." someone please shed some light on this for me
Did you ever figure it out?
04-22-2013 04:56 AM
Kodyston
Quote:
Originally Posted by whynotthinkwhynot View Post
That's right, it's in the valve cover. You'll need a long extension.

This has to do with thermodynamics. That is your engine temp sensor, and it doesn't matter whether it's in the cylinder head or the thermostat housing- it's measuring the coolant temp. I totally forget what that law is called, but it's what keeps wax filled paper cups burning without melting when floating on water. Heat conducts and dissipates quickly to an equilibrium with all things in contact with the source. Your combustion chambers and exhaust gasses can reach temps over 1500F which is more than enough to melt aluminum. Yet it doesn't because around that aluminum is coolant under pressure flowing through the cylinder head. That acts as a heat sink and pulls excess heat from the combustion chambers out to the radiator where it is cooled off.

Yes, I'm not totally right, it does matter where the temp sensor is located in the cooling system. In the center of the cylinder head is the most efficient place because that's closest to where the majority of heat is being created. In this case, it's a matter of reaction time. Yes, the heat will dissipate and the system will reach equilibrium eventually, but it will change faster closest to the heat.

People who use different terminology are not wrong either. The temp sensor is in the cylinder head- right? It is measuring the cylinder head temp- right? They are only wrong if they think that the cylinder head is hotter than the coolant for more than a split second. The exhaust is, but that's not fluid cooled is it?
I found this extremely interesting. Just thought I'd let you know that... lol
04-21-2013 08:31 AM
whynotthinkwhynot That's right, it's in the valve cover. You'll need a long extension.

This has to do with thermodynamics. That is your engine temp sensor, and it doesn't matter whether it's in the cylinder head or the thermostat housing- it's measuring the coolant temp. I totally forget what that law is called, but it's what keeps wax filled paper cups burning without melting when floating on water. Heat conducts and dissipates quickly to an equilibrium with all things in contact with the source. Your combustion chambers and exhaust gasses can reach temps over 1500F which is more than enough to melt aluminum. Yet it doesn't because around that aluminum is coolant under pressure flowing through the cylinder head. That acts as a heat sink and pulls excess heat from the combustion chambers out to the radiator where it is cooled off.

Yes, I'm not totally right, it does matter where the temp sensor is located in the cooling system. In the center of the cylinder head is the most efficient place because that's closest to where the majority of heat is being created. In this case, it's a matter of reaction time. Yes, the heat will dissipate and the system will reach equilibrium eventually, but it will change faster closest to the heat.

People who use different terminology are not wrong either. The temp sensor is in the cylinder head- right? It is measuring the cylinder head temp- right? They are only wrong if they think that the cylinder head is hotter than the coolant for more than a split second. The exhaust is, but that's not fluid cooled is it?
04-21-2013 08:22 AM
don627 What is the issue you are trying to solve? The Zetec uses a cylinder head temp sensor it is the dry type and measures the metal temp directly. They don't go bad very often.
04-21-2013 03:09 AM
Kodyston Could possibly be between spark plugs 2 and 3... or under the cam/valve cover? Just have to look around man...
04-21-2013 02:59 AM
Kodyston Coolant as in anti-freeze? Coolant temp sensor as in a thermostat? http://www.wholesalefordparts.com/sh...roduct=8759449 Maybe this will help? Idk. I have a ZETEC so not really sure... should be pretty much the same I would think...Mine is right under the coil pack inside it's housing bolted onto the engine block...
04-21-2013 01:28 AM
erhodes
Coolant temp sensor!

Hey guys I desperately need some help. I need to know where exactly the coolant temp sensor on a 2005 ford focus ZX5 with the 2.0L duratec is. I was sold a coolant temp sensor today in an effort to solve an issue ive been experiencing. Ford parts calls the sensor in the middle of the head in between the 2 and 3 coils a manifold temp sensor-not a cylinder head temp sensor. but they do not call out a coolant temp sensor. I cannot find any info on this anywhere on the web. Everyone says "they don't have an ECT, they have cylinder head temp sensors." someone please shed some light on this for me

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -5. The time now is 07:30 PM.


Copyright 2002-2015 FocusFanatics.com. All Rights Reserved : Privacy Policy : Advertise Information

Focus Fanatics Ford Focus Forum offers many fun ways for you to engage with other Ford Focus Owners from across the world. Whether it be about the aftermarket performance modifications, technical how-to's, European tuned suspension or awesome fuel economy similar to the Mazda CX-3, Audi S3, Mazda MX-5 Miata and Acura TLX. You can find all Ford Focus, Focus ST and Focus RS related information here. Join our Ford Focus discussion forums and chat with local Focus enthusiasts in your area. If you own other makes have a look at Challenger Hellcat Forum, Charger Hellcat Forum, Cadillac ATS-V Forum, Cadillac ATS Forum, Cadillac CTS-V Forum, Lexus RC-F Forum, Lexus GS-F Forum, Mercedes GLA Forum, Mercedes GLE Forum, Civic Type-R Forum and Volvo XC90 Forum.





Search Engine Optimization by vBSEO 3.6.1