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Discussion Starter #1
I have 2007 base model S the with 2.0 around 182k on it. CEL came on pulled the code and it’s a P0128. Coolant thermostat. Coolant temp below thermostat regulation temperature. Is what my scanner told me.
I’ve noticed that in the past week or so the heat is definitely not hot anymore luke warm at best. I am assuming that I should replace the thermostat but when looking it up there are 2 different options. One with or without the sensor. I don’t have the time to take the old one off to see if it has the sensor or not. I went onto fords website and put in my vin thinking that would narrow it down for me but both parts came up with and without a sensor. Anyone have any input on this? I’m thinking I might just have to order both and return the one that I don’t need.
The coolant is clean did a full flush around 20k ago.

Thanks!
 

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I have repeatedly asked & challenged FF members to show me a (2000-2007) Focus with a T-stat that has a sensor. No one has come forward with any info to prove this animal exists.

I have never seen a Focus "with sensor" or a Focus that has wiring provisions for the sensor. (2000-2007)

Coolant system temps are (extrapolated) calculated based on CHT sensor readings.

Gd Luck
 

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If yours has the sensor you should be able to easily see the sensor/connector under the large water outlet port:





Without the sensor (no connector)


Paul
 

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A quick look would show you if you do or not.........If not I could guess that you don't thou.
 

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Discussion Starter #6
Yes it's the one with a sensor

Well I am pretty sure I do have the one with the sensor. I took a look and there is an electrical connector hooked up to it.

Focus 2_LI.jpg

Focus 1222_LI.jpg
 

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Well I am pretty sure I do have the one with the sensor. I took a look and there is an electrical connector hooked up to it.
You might have a t-stat with sensor, but I can not see this in the pictures you posted. That bugger is hidden & is tucked away.

Careful, I do vaguely remember a connector in that exact area (on my car) but that connector does not connect to the t-stat. IIRC it is a floating harness connector which connects to nothing except the mating harness. I think that is what is shown in your pictures. Go look again.

PLEASE post back once you get absolute confirmation. Thanks!
 

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To OP: i had the exact same problem. Garage wanted CAN 500$ to replace.

I took the plundge. I just finished replacing the T-STAT on my 2005 Focus. I dont know your skills, but here is what i did to EASILY replace the t-stat. The keywords are easily and t-stat. Because, its no easy job to replace a t-stat in that cramped space.

0) empty radiator using the cork driver side on the radiator

1) Remove/loose/replace serpentine belt
- remove serpertine belt protector case (from bottom)
- release tension using the tensionner bolt
- take off/replace serpertine belt

2) remove coolant reservoir
- unbolt coolant reservoir (1 bolt onto fender)
- slide it up (pin is toward windshield)
- put it aside

3) slide out p/s pump
- unbolt the 3 easiest bolts (you can see them)
- the fourth one is a bummer.... the p/s pressure sensor line is in the way
- using a 10mm ratchet/open wrench (buy/rent one youll need it), unscrew while pulling away the pump from its base
- slide p/s pump on the left

4) remove passenger side headlamp (it creates way more space to work on t-stat)
- remove two upper bolts
- one in the fender
- unplug connectors
- put it away

5) finally the t-stat
- detach the bottom end of the big hose going from t-stat to bottom of radiator
- leave the t-stat end of that big hose on the t-stat
- compress the clamp and remove the smallest hose from the t-stat
- you will now have easy access to the three bolts
- remove the t-stat as a whole with the big hose

6) putting it together
- rest the t-stat on a flat surface
- mark/scribe the relative position of the big hose onto the defective t-stat
- unclamp the big hose
- using the scribed marks, fit the hose on the new t-stat at the same position you marked it, making sure the clamp is a the exact same position it was

7) back to engine
- lube the t-stat gasket with coolant
- reposition the t-stat on the engine
- screw partially the the lowest bolt
- then the two upper ones
- check fitting of the hoses
- torque the t-stat bolts (89lbs)
- clamp the smallest hose
- clamp the bigger hose at the bottom of radiator

8) p/s pump reinstall
- this is the bummer
- you have to begin with the lowest passenger side bolt
- the space between the head of that bolt and the p/s pressure line is minimal, so you have to pull the pump toward the front of the engine while screwing mm by mm the bolt. Again, an 10mm open ratchet wrench is your friend. I did not have one, so i has to torque that bolt 1/8 of turn at a time.....

- - -

Again, this is not the shortest (time related) way to do the job, but its the easiest way to have full access to that delicate part - the t-stat.

i finally have heat!
 

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And I used to b-tch about removing 2 bolts on GM ones to remove stats.............I was young and stupid................when you practically need a college education just to yank a freakin' stat, well, it's gettin' close to time for me to retire it seems.

I have to yank the intake manifold to change plugs on my Nissan....................(smoke coming from ears)
 

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Discussion Starter #11
What I did was I took off the power steering reservoir which gave me a little room. And my best $10 ever spent was on a pair of angled long reach pliers made it a breeze undoing the clamps.
 

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To OP: i had the exact same problem. Garage wanted CAN 500$ to replace.

I took the plundge. I just finished replacing the T-STAT on my 2005 Focus. I dont know your skills, but here is what i did to EASILY replace the t-stat. The keywords are easily and t-stat. Because, its no easy job to replace a t-stat in that cramped space.

0) empty radiator using the cork driver side on the radiator

1) Remove/loose/replace serpentine belt
- remove serpertine belt protector case (from bottom)
- release tension using the tensionner bolt
- take off/replace serpertine belt

2) remove coolant reservoir
- unbolt coolant reservoir (1 bolt onto fender)
- slide it up (pin is toward windshield)
- put it aside

3) slide out p/s pump
- unbolt the 3 easiest bolts (you can see them)
- the fourth one is a bummer.... the p/s pressure sensor line is in the way
- using a 10mm ratchet/open wrench (buy/rent one youll need it), unscrew while pulling away the pump from its base
- slide p/s pump on the left

4) remove passenger side headlamp (it creates way more space to work on t-stat)
- remove two upper bolts
- one in the fender
- unplug connectors
- put it away

5) finally the t-stat
- detach the bottom end of the big hose going from t-stat to bottom of radiator
- leave the t-stat end of that big hose on the t-stat
- compress the clamp and remove the smallest hose from the t-stat
- you will now have easy access to the three bolts
- remove the t-stat as a whole with the big hose

6) putting it together
- rest the t-stat on a flat surface
- mark/scribe the relative position of the big hose onto the defective t-stat
- unclamp the big hose
- using the scribed marks, fit the hose on the new t-stat at the same position you marked it, making sure the clamp is a the exact same position it was

7) back to engine
- lube the t-stat gasket with coolant
- reposition the t-stat on the engine
- screw partially the the lowest bolt
- then the two upper ones
- check fitting of the hoses
- torque the t-stat bolts (89lbs)
- clamp the smallest hose
- clamp the bigger hose at the bottom of radiator

8) p/s pump reinstall
- this is the bummer
- you have to begin with the lowest passenger side bolt
- the space between the head of that bolt and the p/s pressure line is minimal, so you have to pull the pump toward the front of the engine while screwing mm by mm the bolt. Again, an 10mm open ratchet wrench is your friend. I did not have one, so i has to torque that bolt 1/8 of turn at a time.....

- - -

Again, this is not the shortest (time related) way to do the job, but its the easiest way to have full access to that delicate part - the t-stat.

i finally have heat!
WilsonStaff
Thank you for that! I need to replace the t-stat on my 2005 ZX4.

BTW Isnt the PS pump reservoir mounted differently on the 2007 (on the pump) vs on the R strut tower on 2005 and earlier?

Paul
 

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Discussion Starter #15
To OP: i had the exact same problem. Garage wanted CAN 500$ to replace.

I took the plundge. I just finished replacing the T-STAT on my 2005 Focus. I dont know your skills, but here is what i did to EASILY replace the t-stat. The keywords are easily and t-stat. Because, its no easy job to replace a t-stat in that cramped space.

0) empty radiator using the cork driver side on the radiator

1) Remove/loose/replace serpentine belt
- remove serpertine belt protector case (from bottom)
- release tension using the tensionner bolt
- take off/replace serpertine belt

2) remove coolant reservoir
- unbolt coolant reservoir (1 bolt onto fender)
- slide it up (pin is toward windshield)
- put it aside

3) slide out p/s pump
- unbolt the 3 easiest bolts (you can see them)
- the fourth one is a bummer.... the p/s pressure sensor line is in the way
- using a 10mm ratchet/open wrench (buy/rent one youll need it), unscrew while pulling away the pump from its base
- slide p/s pump on the left

4) remove passenger side headlamp (it creates way more space to work on t-stat)
- remove two upper bolts
- one in the fender
- unplug connectors
- put it away

5) finally the t-stat
- detach the bottom end of the big hose going from t-stat to bottom of radiator
- leave the t-stat end of that big hose on the t-stat
- compress the clamp and remove the smallest hose from the t-stat
- you will now have easy access to the three bolts
- remove the t-stat as a whole with the big hose

6) putting it together
- rest the t-stat on a flat surface
- mark/scribe the relative position of the big hose onto the defective t-stat
- unclamp the big hose
- using the scribed marks, fit the hose on the new t-stat at the same position you marked it, making sure the clamp is a the exact same position it was

7) back to engine
- lube the t-stat gasket with coolant
- reposition the t-stat on the engine
- screw partially the the lowest bolt
- then the two upper ones
- check fitting of the hoses
- torque the t-stat bolts (89lbs)
- clamp the smallest hose
- clamp the bigger hose at the bottom of radiator

8) p/s pump reinstall
- this is the bummer
- you have to begin with the lowest passenger side bolt
- the space between the head of that bolt and the p/s pressure line is minimal, so you have to pull the pump toward the front of the engine while screwing mm by mm the bolt. Again, an 10mm open ratchet wrench is your friend. I did not have one, so i has to torque that bolt 1/8 of turn at a time.....

- - -

Again, this is not the shortest (time related) way to do the job, but its the easiest way to have full access to that delicate part - the t-stat.

i finally have heat!
WilsonStaff
Thank you for that! I need to replace the t-stat on my 2005 ZX4.

BTW Isnt the PS pump reservoir mounted differently on the 2007 (on the pump) vs on the R strut tower on 2005 and earlier?

Paul



Paul this is where it's mounted on my 07
 

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Paul this is where it's mounted on my 07


AMRiley23 thanks!
On my 2005 the PS reservoir is mounted on the R strut tower. My 2002 is the same. I think they were all that way 2000-2005 or 2006. Not sure if the location changed 2006 or 2007.

Paul
 

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Hi all,

I have an 2005 Mk2 Focus 1.6 petrol Ti-VCT which has the electronically controlled thermostat.
I am struggling with overheating issues, I wonder if anyone has any good tips

After seeing the typical symptoms (pressure cap opens after it can't take it anymore and coolant is released through the cap the rest boils) I have found that the thermostat does not open. There is no or barely any circulation through the radiator.

The dashboard gauge inside raises to 75°C normally, but stays there even if temperatures are way above 100°C

Just to cross out other possibilities:
- Using a garden hose I flushed all lines through the engine, the hoses, the radiator, there is no blockage in the system
- the water pump is in good condition and creates the require head pressure
- de-airing valve seem to be working fine
- thermostat has been replaced, same symptoms with the new one
- coolant thermal sensor (on the other side of the engine) replaced, same symptoms with the new one
- cylinder head is sound, not cracked (checked by mechanic + coolant is clear)
- Expansion tank cap replaced

So all I have left to assume is that the thermostat doesn't get the electronic control signal to open. This type of thermostat doesn't open just by itself if dipped in boiling water(tested). I followed the wires from the thermostat housing to the central box where a bunch of wires go and found no physical injury.
I checked all the fuses (both fuse boxes) which I imagined might have a role in temperature or engine control, all sound.

Is there anything I can do to find out more? Is there any way to fix this if the fault is in the central electronics?

If everything else fails, does anyone have experience with using a conventional thermostat instead? It looks like the housing matches, anyone knows if it really does? Can it cause a problem in engine control if thermostat wires are not connected (as there is nowhere to connect them)?
Temperatures is still a problem, the best conventional thermostat I could find opens at 92 °C while the original opens at 98 °C.
It still might be okay I guess, if 92 is measured before the engine and 98 is originally measured after the engine at the thermal sensor, then close enough I assume.

Any comments, tips appreciated!
 

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I once replaced three thermostats in a row on my parents' car before getting one that worked. Bad day on the assembly line at the parts factory, I guess.

I would suspect the new stat is no good, or the electrical connector is faulty, before I would assume problems with the computer.

Are your fans coming on normally?
 

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We can probably cross out the thermostat. I managed to get it fully open by connecting 12 V DC current two it's two pins. I also found out that very slowly, even if only a very little but partly it also opens if kept in boiling water for long enough, without electrical connection.

I managed to install a simple mechanical thermostat, I will have to get a better size sealing rubber for a small leak but basically it fits and works as expected, the radiator is hot now when the engine is hot. And I could drive around without turning my car into a boiler kettle.

I'm still worried about the fan. I have seen it working occasionally but I have doubts about it... Maybe I'm just too much into the idea that computer control goes crazy and project that idea to the fan too :) The fan is definitely working if I connect direct 12 V to it's two power pins.

I'm worried that engine temperature and coolant temperature displays are unreliable and I also blame the computer for that...
Engine temperature starts from 58 °C when the car has been stopped for days, the ambient temperature is 15 °C so the engine cannot possibly be any warmer than that.
Coolant temperature gauge stops raising after reaching 75°C, but the coolant is a lot hotter. (old and new sensors both)

Anyway I would like to have a valid engine temperature to be able to check whether the mechanical thermostat had been properly selected and engine temperature is near optimal. The current unreliable(?) measurement shows about 130-140 °C when driving warm, but I'm still searching for what the optimal value should be.

I also like to measure the coolant temperature, to check fan operation. I'll probably install a mechanical thermometer, cutting trough a rubber hose or something.

The electrical connectors look okay, clean, not broken, not rusty or anything. I can measure voltages in between the pins, the wires are alive.

EDIT: Reading back I think I was probably not clear enough:
By "engine temperature" I mean the value displayed in the self test menu (press and hold left hand whisker button and turn ignition on)
As being way higher than 100 °C, I assume this is not from the coolant sensor but measuring the iron block temperature somewhere, but I don't know where the sensor is located.
Coolant temperature gauge on the dashboard is not itself faulty, the gauge swipe test passes okay, it just apparently gets wrong value from the PCM.
 

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I have found that the temperature gauge is not ment to show the measured temperature, and engine temperature is not measured at all, there is only the coolant sensor.

- Accurate coolant temperature measurement is available trough OBD diagnostics, I just bought a bluetooth OBD2 plug, it is really cheap

- The dashboard gauge shows stable but bullshit value, this is not a computer error, it is reported by many. It looks like Ford doesn't entrust a regular user with such a difficult task as reading a temperature gauge, probably to avoid false error reports because the temperature changes (lol)
It looks like the gauge is only good to detect overcooling.

- The engine temperature = coolant temperature + 40 °C. Fixed. That's why it's "measured" hot 58 °C with the cold, actually 18 °C engine. (Some reported the fixed difference as 30 °C, I guess it depends on the motor type, Mk2 1.6 petrol Ti-VCT is 40)
 
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