I've been trying to fix a friends fiesta 1.6 zetec s (the one with all the skirts and alloys etc). It is overheating after about 25 miles and the fan comes on when the car is travelling along. I am thinking that it is the thermostat, is there anything else it could be?
I took it out for a short thrash and could only get the temperature to half way at which point the fan was coming on. could this mean the sensor for the fan swithes on too early?
any thoughts would be apreciated. it recently had a new water pump to try and cure this problem.
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Is the temperature guage registering high? (is the heater blowing very hot air?)
There could be an airlock..
Is it losing water or is the level low? Is the oil level correct?
A new water pump is $£s, a new thermostat is £s.. does not seem a logical approac.. did a garage do the job?
You sat the temperature guage only reads half way so why say it is overheating? (the guage may be faulty or the temperature sensor faulty) Fan is controlled by the PCM (Powertrain Control Module) using temperture from the sensor..
madf
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thanks for the reply
the temperature gauge was reading mid way when i drove it however i think the fan was on at this temp, I think it has a 2 speed fan?
She drives it about 25 miles before it start to go into the red. then it will drop back down again. I guess when the fan goes into the faster speed.
is the sensor from the water temp on the block somewhere as i cant see one on the head? also is the thermostat housing on the block?
a garage did do the job, i think they chaged the water pump and checked the thermostat with no success, I was just going to get a new thermostat as these are cheep aren't they?
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oh yes i forgot the water level doesn't drop, and the oil is O.K.
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25 miles is a long drive for this to occur.Depending on circumstances.Ie is the engine under load when it occurs..or normal cruising speed.You wasnt specific. So its not easy to say/give an oppinion?
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Steve
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25 miles is enough to really heat soak the engine/cooling system. 2 things spring to mind,
1 the radiator has accumulated some silt which is being disturbed.
2 a hose may be collapsing internally after this period and partially blocking the water flow.
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thanks for the replys
in answer to steves question the car isn't under too much load, i think she thrashes it but not red lining it or anything, we live in norfolk so it not going up steep hills and not not towing a trailer etc
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Could be wrong but doubt stat is the problem..If it was it would overheat well before the 25 mile drive I think.. as would blocked rad or collapsed hose.
Depending on air temp/some rad fans do come on early so as to avoid an overheat.By early I mean just above normal on dash temp guage
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Steve
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I had a Zetec 1.25 (just lower than yours) and if i was stuck in traffic wheither it was motorway or A or B road the temp gauge would rise JUST abouve the M on morm but not enough to go in to the red if you know what i mean then the fan would come in. i had the car nearly 2 years before reluctantly selling it for a diesel focus which handles alot better.
I don't think you have too much to worry about, 25 miles is a pritty good drive and if you think about it everything will be up to temp so if your stuck in traffic it will get abit hot due to the no air flow through the radiator because your stationally or driving slowly!
If the needle is really up the outer range of the red when the fan comes in i would start worrying because this could start upsetting your head gasket!!
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