Rapid Temp Gauge Movement

[Dav3y]

Hey guys, got abit of a problem i need to get to the bottom of asap.

I drive a 2001 Fiesta Zetec-lx with a 1.25 SE engine.

When driving about my temperature gauge plays about, and constantly waves between the centre of "normal" and right past red. I know that the slightest movement on this gauge is a few degrees, so there is no way it can possible heat and cool as quickly as the gauge is telling me. The needle constantly waves between centre and past red (it never used to pass the middle, ever) and if i go round a roundabout or right hand corner the gauge goes down, but then returns to waving between the two again.

I broke my HCV (by removing the pipes, the plastic just crumbled) so i have a new one on its way. I'm hoping this might be the issue? I have bled the system of air by running the engine with the water bottle cap off and squeezing the rad pipes, and slowly adding water (as i lost some when i removed the hcv - i have now bypassed with copper pipe for now) and no air was coming out so i don't think an airlock is the problem? There is no pattern, such as (and i would never do this) if i was redlining the enging i could understand the gauge would obviously go up as it would be getting hotter, and if i was sat in traffic it might get warmer as theres no air flowing through the radiator, but i could be driving at 60-70mph and it will be waving between red and normal, but for example i was going up a 11% gradient of a dual carriageway (which is 50mph) and i had to do it in third with a lot of throttle to keep at 50, and the gauge was going DOWN! - surely would have gone right up as i had to use quite a few revs to keep upto speed?

I can think of things that might be the issue, but i don't know what or even where to start on it. Out of:-

Heater control valve

Thermostat

Temperature sensor

What could be causing the gauge to rapidly move as it does?! I feel this is an urgent matter, as i can't be sure if me engine is overheating or not and i dont want to make it worse :(

I would be thankfull for any and all helpful replies!

- Davey

[Lenny]

Hey guys, got abit of a problem i need to get to the bottom of asap.

I drive a 2001 Fiesta Zetec-lx with a 1.25 SE engine.

When driving about my temperature gauge plays about, and constantly waves between the centre of "normal" and right past red. I know that the slightest movement on this gauge is a few degrees, so there is no way it can possible heat and cool as quickly as the gauge is telling me. The needle constantly waves between centre and past red (it never used to pass the middle, ever) and if i go round a roundabout or right hand corner the gauge goes down, but then returns to waving between the two again.

I broke my HCV (by removing the pipes, the plastic just crumbled) so i have a new one on its way. I'm hoping this might be the issue? I have bled the system of air by running the engine with the water bottle cap off and squeezing the rad pipes, and slowly adding water (as i lost some when i removed the hcv - i have now bypassed with copper pipe for now) and no air was coming out so i don't think an airlock is the problem? There is no pattern, such as (and i would never do this) if i was redlining the enging i could understand the gauge would obviously go up as it would be getting hotter, and if i was sat in traffic it might get warmer as theres no air flowing through the radiator, but i could be driving at 60-70mph and it will be waving between red and normal, but for example i was going up a 11% gradient of a dual carriageway (which is 50mph) and i had to do it in third with a lot of throttle to keep at 50, and the gauge was going DOWN! - surely would have gone right up as i had to use quite a few revs to keep upto speed?

I can think of things that might be the issue, but i don't know what or even where to start on it. Out of:-

Heater control valve

Thermostat

Temperature sensor

What could be causing the gauge to rapidly move as it does?! I feel this is an urgent matter, as i can't be sure if me engine is overheating or not and i dont want to make it worse :(

I would be thankfull for any and all helpful replies!

- Davey

Hi Davey.

with the engine off,

open the oil filler cap on the engine and have a look under the lid,

if there is any sign of white or gunk around the inside of the cap this would be a sign that you head gasket is on its way out. this can cause overheating problems,

also

you said you had topped the coolant up with water,

maybe the glycol levels in the fluid is now less than specified by the manufacture so a full flush down and refill with some ready mixed coolant may solve the fluctuation, but if you were to flush out the system i would also recommend changing the temperature sensor, they are less than £10 from ford and a simple unplug of the cable then unscrew the sensor, screw in the new sensor and reconnect the plug,

job done.

other than that im clueless mate,

could be the water pump if failing either but then you would be losing coolant on the ground when parked.

so not likely or you would have said you noticed it.

[Dav3y]

Hey Lenny, Thanks for the reply :)

I did consider head gasket but as im loosing neither coolant or oil (and i did the check you mentioned, and my oilcap has dark black oil on it) so i knew i could at least put that conclusion out of the window.

Is there something special i am to put in the coolant system? I was just aware that water was all i need (and obviously a mixture of anti-freeze). Learn new stuff all the time aha :) How do i do a coolant system flush and refill? The only real way i know of refilling a coolant system is running the engine with the cap off and slowly filling it as it goes down (something dad showed me) if there is a better proper way of doing it i would for sure give it a go :)

[Lenny]

Hey Lenny, Thanks for the reply :)

I did consider head gasket but as im loosing neither coolant or oil (and i did the check you mentioned, and my oilcap has dark black oil on it) so i knew i could at least put that conclusion out of the window.

Is there something special i am to put in the coolant system? I was just aware that water was all i need (and obviously a mixture of anti-freeze). Learn new stuff all the time aha :) How do i do a coolant system flush and refill? The only real way i know of refilling a coolant system is running the engine with the cap off and slowly filling it as it goes down (something dad showed me) if there is a better proper way of doing it i would for sure give it a go :)

their is usually a valve or tap on the bottom of the radiator to flush the system out,

leave the top cap off to allow the air in to flush the system,

then when topping it back up do the method you said in the post above by squeezing the pipes etc.

ready mixed coolant saves alot of science in mixing your own.

[Dav3y]

Thanks :D

I just found a video on youtube of how to flush out an engine and replace the thermostat (shame it was a 1.3 endura though!) but i think i know enough now to have a go. When i replace the hcv and possibly thermostat, is it worth me sort of blasting the hose through the heater matrix pipes to clean the gunk out?

[Lenny]

Thanks :D

I just found a video on youtube of how to flush out an engine and replace the thermostat (shame it was a 1.3 endura though!) but i think i know enough now to have a go. When i replace the hcv and possibly thermostat, is it worth me sort of blasting the hose through the heater matrix pipes to clean the gunk out?

NO HOSE!!

the fins in the radiator are very fine and they are set in their like a 1 piece line of alluminium all woven in a zig zag formation, the hose has the potential power to nock these fins out of place and reduice the ventalation of the radiator by bending the fins and restricting air flow,

the best stuff i would recommend is a bottle of Holtz Radiator Speed Flush,

but take my word for it mate, follow the instruction on the bottle exactly lol drain the system then fill with water and add the bottle of holts, leave the engine running for 10-20 munutes and rev to flush the fluid around the radiator abit to loosen the sludge then drain ot out, fill with water again and run for 2 minutes then drain it out,

followed by filling with ready mixed coolant and seal her up.

i used the stuff before on my old 1997 1.3 starlet but i thought the longer i left the cleaner in their shir the better it would clean right?

WRONG!

i left it in their for two weeks then it cleaned the inside that good that it broke the seal in my water pump resulting in me needing a new one of those too, apparently the radiator flush has some caustic content in it which is great for short term cleaning and will blast lime scale off in seconds, but left in contact with metal for long periods it will eat away at it.

so end results the Holts Radiator Flush is quality stuff and really does a great job,

but follow the instructions on the bottle, i think your supposed to leave it in for 20 minutes or somthing then flush it out.

wear gloves because it is caustic

and wath your eyes if spraying it around too.

here is a link to the stuff

http://www.ebay.co.u...=item1c253e4ba3

also next time your doing an oil change,

use a bottle of this stuff its also very good. but again read the label lol

http://www.ebay.co.u...=item3cc6207587

[MarkJA]

Did this post ever get solved?

Hi, first post so sorry if I am not following the rules.

I have exactly the same problem on my 1.25 zetec s Ghia, bought today :-( and which also has the guage rise into the red but seems to vary massively within a few seconds, including on corners.

No water seemed to be lost, but I am pretty sharp at spotting temp rises so cannot be sure if it was my fast reaction or that the problem is just the level on the guage but engine temp is fine?

[Chezz]

Hi guys,

I have a Ford Fiesta eco boost mk7 (14) plate 

Over the recent days my temperature gauge has been fluctuating from 2 to 3 bars back to 2, it hardly reaches 4 (as it should always sit on 4) that’s only after a hour journey, I’ve changed the temp sensor and I still have the problem? 
 

I have a thermostat housing is it worth replacing this? 
 

if not any other ideas?

thanks