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Running Temp On Gauge


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Hey Guys,

I know this may sound stupid but ive just started driving a MK1 Focus TDCI and the car drives spot on only when driving it the temp needle will go up to half way when giving it a bit of stick and then when doing 40-50 it will go back down again to just above the white square

could someone please tell me where normal running temp is on the gauge as the fan isnt kicking in and the needle is about half way on the gauge im worried that when ive got to drive it to london its gunna get hot and may overheat and i would like to avoid having to do the head gasket due to it overheating its fine when driving around town as it barely gets above the white square but blowers do bolw warm when the needle is there

sorry to sound a thick


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The temp gauge does not refer to engine temp it refers to coolant temp and as thermostats open and close you will see fluctuations thats how the system works unless the needle doesnt move or its in the red theres nothing to worry about its a misconception that it refers to the temp of the engine it doesnt

Diesels take longer to warm up using the blowers takes heat out of the coolant and engine low speeds produce less engine heat

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Thanks for that but I when should the fan kick in as I haven't heard it kick in but I'll just monitor the gauge and if it gets near the red then I take it thermostat is broken

Sent from my Nexus 5 using Ford OC mobile app

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you wont get the fan to kick in it shouldnt unless the engines too hot in a diesel which naturally runs colder youll be doing well to make the fan kick in maybe if you sat and let it idle for 40 mins you might get it to kick in halfway is normal running temp or slightly under

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sorry to say on the mk1 thats not true read any ford manual it tells you its a coolant temp gauge yes it uses one sensor but it does 2 jobs monitors head temps and then uses that to determine coolant temp by sending the info back to the ecu which then determines the temp of the coolant on the gauge .

the temp will go up then as the thermostat opens and flows through the rad due to the cold air and temps at the moment the coolant overcools this is when the gauge will drop to reflect this as a result the thermostat recloses and feeds the coolant through the head and back to the expansion tank missing out the rad to maintain optimum temperature this is when the coolant temp stabilises, the head temp is found on the dash trick which is about 40 degrees higher than the coolant temp once the car is up to full temp it will sit in the middle depends on the length of the journey if its short distances then it wont get hot enough

on the dash trick youll find the head temp as say 108 degrees which means coolant temp is 68 degrees 130 degrees head 90 degrees coolant and so on

as long as its not up and down like a yoyo and isnt in the red theres no issue if it constantly goes up and down from midway to cold then theres an issue

It's doing exactly what it's supposed to, the t-stat closes temp goes up
to the rated temp on the t-stat, then it opens cooles down, closes and
so on and so on.Thumbup19,5B1,5D.gif.pagespeed.ce.-r7mnT your in good shape. i notice mine more in the winter.

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from what he has said so far no he said it went up he gave it some stick so more airflow and the pumps running faster and the temp went down but hasnt said if its doing this continously or stabilising in the centre,

if its up and down all the time then yes it needs checked if it stabilises then its okay but no answer has come back as of yet.

he thinks that at halfway the fan should be coming on which is normal running temp so ive no idea why he thinks the fan should come on unless he thinks halfway is too hot which it isnt ,also he states the blowers blow warm the blowers also take heat away from the engine via the coolant so this will take longer in cold weather to heat up until the temp gets into double figures outside.

a diesel will take a while to heat up even longer with the blowers on it appears he doesnt quite understand a cooling system hence the long reply

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the workshop manual can tell you what it wants but the fact is it does 2 jobs and determines head temp on the dash trick and coolant temp on the gauge look at any manual mate it shows the dash layout and tells you coolant temperature gauge from the fords ecu manual mate focus mk1 and mondeo Coolant temperature (ECT) Your engine's
overall temperature affects the knock threshold, so the ECU needs to
know this value. Additionally, it needs to know when to turn on the
fans. The coolant temp also affects cold start functions including the
first closed loop transition. On the regular Zetec Focus, there is a
sensor that reads the metal temperature on the head, then the ECU uses a
transfer function to infer coolant temp this registers the coolant temp on the gauge
the gauge indicating in the red zone shows that the coolant temp has exceeded the maximum and the cooling system is unable to cool the system via the electric fan in the engine bay to prevent engine damage 2 pistons will revert to the function of air pumps thus reducing engine power.

forget the manuals you have to understand the whole sytem the manual tells you half the story youre not technically wrong theres just far more to it than those manuls tell you and if its haynes i would ignore most of it anyway haynes is okay for some things but it just doesnt give enough info all on here is from fords own ecu and engine manual for technicians dont ask i cant say where i got it from other than i shouldnt have it

the thermostat does not restrict the flow it has 2 holes... with the thermostat closed coolant flows through the secondary hole into the small coolant hose along the front of the engine bay into the recovery tank this hot coolant is then via the pump sucked up into the pump and flows back through the head this cycle continues till optimum temperature is reached at the preset temperature the wax thermostat opens allowing the coolant to flow through the top hose into the radiator where it is cooled, and via the pump through the engine this cycle repeats until the coolant temperature drops usually via cold air overcooling the coolant since this could be disasterous to add cold coolant to a hot engine the thermostat closes and the coolant flows back through the coolant resovoir where it can maintain the coolant temperature this process wil be indicated by a decrease on the coolant temperature gauge. the purpose of this sytem is to achieve faster warm up temperatures and maintain a high operating temperature within the engine as parts wear out faster at low temperatures

The pump sends the fluid into the engine block, where it makes its way
through passages in the engine around the cylinders. Then it returns
through the cylinder head of the engine. The thermostat is located where
the fluid leaves the engine. The plumbing around the thermostat sends
the fluid back to the pump directly if the thermostat is closed this is done via a bypass hose to the expansion tank. If it
is open ie coolant is up to temperature, the fluid goes through the radiator first and then back to the

The thermostat's main job is to allow the engine to heat up quickly, and
then to keep the engine at a constant temperature. It does this by
regulating the amount of water that goes through the radiator. At low
temperatures, the outlet to the radiator is completely blocked -- all of
the coolant is recirculated back through the engine to the expansion tank.

Once the
temperature of the coolant rises to between 180 and 195 F (82 - 91 C),
the thermostat starts to open, allowing fluid to flow through the
radiator. By the time the coolant reaches 200 to 218 F (93 - 103 C), the
thermostat is open all the way.

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Been on a big drive today and temp gauge has just sat in the middle and not moved fan kicked in when I got home seems to working fine thanks for all advice you all top lads

Sent from my Nexus 5 using Ford OC mobile app

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all seems okay then no probs

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Just always drove petrols you see

But all seems ok

But thanks you guys are the dons

Sent from my Nexus 5 using Ford OC mobile app

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Diesels run cooler and can take a while to heat up thats why some people in the winter fit a cover over the rad to heat it up quicker i know some of the taxis do and trucks if its cold enough if poss it helps to not have the blowers on max hot midway helps a bit

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