help with focus overheat problems

help with focus overheat problems

Author
Discussion

steveo3002

Original Poster:

10,525 posts

174 months

Friday 17th March 2017
quotequote all
i can get my scanner thingy to display live readings from the head sensor , but without knowing what reading i should expect its no use

im told head sensor feeds the ecu which then tells the fan control to turn on , but id need to know at what xx degrees , its alos suggest the temp gauge is more of an indicator and cant be trusted to show any sort of accuracy ??

Edited by steveo3002 on Friday 17th March 18:32

GreenV8S

30,198 posts

284 months

Friday 17th March 2017
quotequote all
I wouldn't expect the gauge to be accurate, but it should be reasonably consistent. If it's showing the temperature varying rapidly, it's quite important to know whether that's caused by the actual temperature fluctuating, or just a wiring/gauge issue.

steveo3002

Original Poster:

10,525 posts

174 months

Friday 17th March 2017
quotequote all
personally i dont think an engine can go from normal to red hot and back again within 10 seconds, so thinking thats an elec glitch

although that doesnt explain why it boiled up in the first place

GreenV8S

30,198 posts

284 months

Friday 17th March 2017
quotequote all
Air pockets can cause those wild swings. But an electrical glitch or faulty sensor could cause them too.

AdamIndy

1,661 posts

104 months

Friday 17th March 2017
quotequote all
steveo3002 said:
personally i dont think an engine can go from normal to red hot and back again within 10 seconds, so thinking thats an elec glitch

although that doesnt explain why it boiled up in the first place
Unfortunately, temp gauges these days are pretty crap. Otherwise known as idiot gauges. They tend to have three positions. Cold, operating temperature and your engine has melted. They aren't linear like you would expect them to be.

The best thing to do is plug your scanner in and if it can read live data then take it for a drive and see what temps it reads.

If it was any other zetec engine then the coolant temp sensor is it the top of the thermostat housing but I know little about the 1.6 (se?).

Normally air locks work themselves out pretty easily unless you have an absolute beast of an air lock then I would be looking elsewhere. Is the temp sensor goosed?

AdamIndy

1,661 posts

104 months

Friday 17th March 2017
quotequote all
Just an idea but you can buy multimeters with temperature probes pretty cheap. https://www.amazon.co.uk/Sealey-MM20-8-Function-Mu...

I have one of these and it's very accurate, as accurate as my digital dash anyway.

You could try taping the probe to one of the rad hoses and see roughly what temperature it is. I have seen temps around 100deg c on my focus. Anything more than 105c/110c then you have issues.

steveo3002

Original Poster:

10,525 posts

174 months

Sunday 19th March 2017
quotequote all
right update if anyones still looking in

driven the car alot and keep stopping to check , at no point does the hoses /rad feel too hot

gauge still shoots from normal to hot and back again in around 10 seconds , seems to happen mostly when going from 70 ish and backing off to 50 , i think its too fast to be a genuine overheat

fan comes on randomly even at speed

i got the machine hooked up and cylinder temp is showing 114 after a long run , hoses felt normal , no fan on , im told fan should come on at 105

does it sound like a duff cylinder head temp sender??

basicly its thinking its hot and its not?

Dogma1978

41 posts

103 months

Thursday 23rd March 2017
quotequote all
Hi you should have two on your car. One is located on the head -

Then there should be one which is screwed into the rad but this tends to activate the fan. The one inthe head would give readings to the ecu. Also check that the thermostat isn't failing. If it sticks in closed position it would also cause engine to overheat

steveo3002

Original Poster:

10,525 posts

174 months

Thursday 23rd March 2017
quotequote all
thanks...got the head one here and will fit it at the weekend

Dogma1978

41 posts

103 months

Thursday 23rd March 2017
quotequote all
If that doesn't fix it then I'd definitely be taking the thermostat out to check it

steveo3002

Original Poster:

10,525 posts

174 months

Friday 24th March 2017
quotequote all
new sensor is in...readings seem a bit random , should it be calibrated or something after fitting?

E-bmw

9,220 posts

152 months

Saturday 25th March 2017
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In a word no.

Just had a thought though, you say it mostly varies when slowing down coming off the motorway.

Is the change in engine speed causing a weakness in the pump to be highlighted.

I did have an old VX several years ago where 75% of the impellor blades had rusted away & at speed it worked well enough, slowing down the temperature would sky-rocket.

steveo3002

Original Poster:

10,525 posts

174 months

Thursday 30th March 2017
quotequote all
genuine temp sender fitted - still the same

not sure what else to do - couple of threads on the forums saying thiers was the ecu , might try a ebay one out of desperation

http://www.focusfanatics.com/forum/general-technic...

steveo3002

Original Poster:

10,525 posts

174 months

Monday 3rd April 2017
quotequote all
second hand ecu does just the same frown

GreenV8S

30,198 posts

284 months

Monday 3rd April 2017
quotequote all
Suggest you buy a thermometer with a remote (wired) sensor that you can position inside the vehicle and see if the top hose temperature is actually varying as your gauge suggests. An ordinary (contact) sensor will read reasonably quickly (tens of seconds) if attacked to metal which is in direct contact with water such as an outlet spigot. Remember to insulate over the outside so that you're only seeing coolant/pipe temp and not an average with air temp.

steveo3002

Original Poster:

10,525 posts

174 months

Monday 3rd April 2017
quotequote all
GreenV8S said:
Suggest you buy a thermometer with a remote (wired) sensor that you can position inside the vehicle and see if the top hose temperature is actually varying as your gauge suggests. An ordinary (contact) sensor will read reasonably quickly (tens of seconds) if attacked to metal which is in direct contact with water such as an outlet spigot. Remember to insulate over the outside so that you're only seeing coolant/pipe temp and not an average with air temp.
yes i had thought of that , im reasonbly sure its not actually overheating but peace of mind and all that

trouble is it goes into limp mode/2cyl mode when it thinks its very hot

Dogma1978

41 posts

103 months

Monday 3rd April 2017
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Have you tried the thermostat as I suggested mate. You've already stated that the cooking system was full of crud. If this is the case the thermostat could be clogged up or at its age it's probably failed. If it's failed in the closed position then the car will over heat. Also would cause the cold pipes after the stat location

steveo3002

Original Poster:

10,525 posts

174 months

Monday 3rd April 2017
quotequote all
Dogma1978 said:
Have you tried the thermostat as I suggested mate. You've already stated that the cooking system was full of crud. If this is the case the thermostat could be clogged up or at its age it's probably failed. If it's failed in the closed position then the car will over heat. Also would cause the cold pipes after the stat location
it had a new one first job i did on it , in desperation ive knocked the guts out of it and been for a jaunt , as expected its very slow to warm up but ive done about 60 miles tonight with no warnings /overheats , the fresh coolant that came out looked fine , no sludge or bits in it

not sure if that means dud new stat ,massive air lock , or that the gutted stat is giving a partially block rad an easy life