Ford Automobiles Forum banner

1 - 20 of 28 Posts

·
Hiding under a Rock
Joined
·
575 Posts
Discussion Starter · #1 ·
I just noticed a bit of steam when I was rolling into the garage. The temperature gauge read smack bang in the middle (as it does all the time so I really don't pay attention). The water level in the expansion tank was higher than usual so I assume it got hotter than it should have been.

So after it cooled down, I ran the motor at idle for about 10 minutes - fan didn't come on once. Once again, the gauge was reading "normal"

I checked the relay, the fuse and the fan and they are all good. Apparently Mr Haynes says now it's down to temp sensor, wiring loom or the ECU. Not much help there.

The behaviour of the gauge hasn't changed so I'm not sure if it's the dodgy gauge or dodgy sensor.

Is there a way to test the sensor without pulling it out?
 

·
Hiding under a Rock
Joined
·
575 Posts
Discussion Starter · #2 ·
Wiring loom between the fuse/relay box and the fan seems ok when checked for continuity.

DMM reads 31kohm when measured the sensor cold.

Not sure what the fan resistor mounted at the bottom of the fan shroud is for, but DMM reads short.

The Haynes manual wiring diagram shows 3 relays (PCM, cooling fan and high speed cooling fan) - what's all that about? Mine has only one cooling fan. The owners manual fuse/relay identification chart isn't particularly helpful either.
 

·
Premium Member
Joined
·
316 Posts
Wiring loom between the fuse/relay box and the fan seems ok when checked for continuity.
DMM reads 31kohm when measured the sensor cold.
Not sure what the fan resistor mounted at the bottom of the fan shroud is for, but DMM reads short.
The Haynes manual wiring diagram shows 3 relays (PCM, cooling fan and high speed cooling fan) - what's all that about? Mine has only one cooling fan. The owners manual fuse/relay identification chart isn't particularly helpful either.
Does your fan come on when you switch on the Air Con?....If so it's still working....My 2.2 has to get very warm before fan comes on....I would give your expansion tank a good clean first & check for cracks as well as the rubber seal in the cap....Hope You get sorted

Sent from my iPhone using Tapatalk
 

·
Mk3 4 LYFE
Joined
·
362 Posts
Forget the tempreture gauge. It's as much use as a chocolate fireguard. It's just an idiot light in rotational form. Goes to dead centre ~60c. Stays there until past overheating, by which time the light is on. Its only use is for showing roughly when the heater will start blowing warm.

Use an OBD reader if you have one. If you don't, the dashboard diagnostics will show cylinder head tempreture. Hold down the trip reset button, turn the ignition on until it comes up with test mode, then press the button to cycle through until you get the xxC display. Here's a good video of it:

The fan is supposed to turn on at 97 or 98c off memory.
 

·
Little Megger
Joined
·
4,329 Posts
Has the fan seized up? Try spinning it by hand. The resistor is for 2-speed operation and the contacts often corrode badly due to its position.
 
  • Like
Reactions: ul9601 and HC56

·
Hiding under a Rock
Joined
·
575 Posts
Discussion Starter · #6 ·
Wiring loom between the fuse/relay box and the fan seems ok when checked for continuity.
DMM reads 31kohm when measured the sensor cold.
Not sure what the fan resistor mounted at the bottom of the fan shroud is for, but DMM reads short.
The Haynes manual wiring diagram shows 3 relays (PCM, cooling fan and high speed cooling fan) - what's all that about? Mine has only one cooling fan. The owners manual fuse/relay identification chart isn't particularly helpful either.
Does your fan come on when you switch on the Air Con?....If so it's still working....My 2.2 has to get very warm before fan comes on....I would give your expansion tank a good clean first & check for cracks as well as the rubber seal in the cap....Hope You get sorted

Sent from my iPhone using Tapatalk
I havent tried that - will need to put it together first. Ever since a "replacement" expansion tank cracked out of the box and lost coolant, i've been keeping eye on the coolant level after driving. long story short, i thought my original Ford one had some cracks on the bottom side so i bought an ebay one, which was a big mistake. i went back to the original one and it's been fine and coolant level never rose. cap is only 6 months old. (bought a Ford one to go with the crappy ebay expansion tank)
 
  • Like
Reactions: HC56

·
Hiding under a Rock
Joined
·
575 Posts
Discussion Starter · #7 ·
Has the fan seized up? Try spinning it by hand. The resistor is for 2-speed operation and the contacts often corrode badly due to its position.
Tried running the fan directly from the battery and it fired up fine, so can't have been seized.

The contact for the connectors for the resistor looks clean.
 
  • Like
Reactions: HC56

·
Hiding under a Rock
Joined
·
575 Posts
Discussion Starter · #8 ·
Forget the tempreture gauge. It's as much use as a chocolate fireguard. It's just an idiot light in rotational form. Goes to dead centre ~60c. Stays there until past overheating, by which time the light is on. Its only use is for showing roughly when the heater will start blowing warm.

Use an OBD reader if you have one. If you don't, the dashboard diagnostics will show cylinder head tempreture. Hold down the trip reset button, turn the ignition on until it comes up with test mode, then press the button to cycle through until you get the xxC display. Here's a good video of it:

The fan is supposed to turn on at 97 or 98c off memory.
I'll give that a go - I can jury rig something to operate fan manually if i cant figure something out, as the fan and the wiring are good.
 

·
Premium Member
Joined
·
316 Posts
Wiring loom between the fuse/relay box and the fan seems ok when checked for continuity.
DMM reads 31kohm when measured the sensor cold.
Not sure what the fan resistor mounted at the bottom of the fan shroud is for, but DMM reads short.
The Haynes manual wiring diagram shows 3 relays (PCM, cooling fan and high speed cooling fan) - what's all that about? Mine has only one cooling fan. The owners manual fuse/relay identification chart isn't particularly helpful either.
Does your fan come on when you switch on the Air Con?....If so it's still working....My 2.2 has to get very warm before fan comes on....I would give your expansion tank a good clean first & check for cracks as well as the rubber seal in the cap....Hope You get sorted

Sent from my iPhone using Tapatalk
I havent tried that - will need to put it together first. Ever since a "replacement" expansion tank cracked out of the box and lost coolant, i've been keeping eye on the coolant level after driving. long story short, i thought my original Ford one had some cracks on the bottom side so i bought an ebay one, which was a big mistake. i went back to the original one and it's been fine and coolant level never rose. cap is only 6 months old. (bought a Ford one to go with the crappy ebay expansion tank)
I bought my Mondeo 58 plate after my 21yr old freelander started showing signs of head gasket gone for 2nd time(notorious k series 1.8).....This was July 18....Mechanic didn't have time to look at it as He was literally snowed under....I took of the still original sticker on expansion tank & sure enough it looked like a shattered windscreen....Ordered a new bottle & begged him to find time to fit, add new coolant but reminded him "WHATEVER YOU DO I DONT WANT ANY ADDITIVES PUT IN" picked it up next day & all good but he admitted he had added only a 1/4 of a small bottle of reputable stuff....I was LIVID!!!.....As it's led to all sorts problems in older cars....He tried to convince me that this stuff is the dogs nuts & He had only used a tiny amount...I got a measly £800 for it,pristine & almost complete restoration until I needed a heart bypass & couldn't work on it anymore the following day against the Mondeo....About 6 weeks back I seen it again for 1st time since trading in....Guy has it totally immaculate & purring like a kitten.... I was gutted, though needing a wheelchair now & falling twice getting out of it, I really had no option....In hindsight I am glad to see it went to someone who obviously loved them & had the health to maintain....But all along that was what the problem was....gauge would sit at normal yet if I opened bonnet I could see a trace of steam when engine was hot & that record breaking heatwave that year I would see the odd trace of water on outside of tank....it was expanding when hot & the tiny cracks were letting air in....I had got into habit of pumping by hand the top hose when missus went into shops etc etc.....9 times out of 10 it was either cold or look warm so I knew there was air locks....middle of heatwave & I'm driving round with heater on full heat lol!!....with all windows down....Expansion tank all along....First mechanic had said definitely no cracks until I peeled of the sticker...." Oh That's knackered" was reply....felt like kicking him in the b***s!!!......Good Luck Bud....Keep us posted....

Sent from my iPhone using Tapatalk
 

·
Hiding under a Rock
Joined
·
575 Posts
Discussion Starter · #10 ·
just did the dash diagnostics - it reads 18 degree C, which is ambient temperature, so i'll have to do it again when it's warmed up.

i have a scanner but for the life of me can't find it. it might be in the boot, which is right up against the garage wall and can't open it (estate) until i get the car off the jacks and roll forward.

thanks guys for your help.
 
  • Like
Reactions: HC56

·
Premium Member
Joined
·
316 Posts
just did the dash diagnostics - it reads 18 degree C, which is ambient temperature, so i'll have to do it again when it's warmed up.
i have a scanner but for the life of me can't find it. it might be in the boot, which is right up against the garage wall and can't open it (estate) until i get the car off the jacks and roll forward.

thanks guys for your help.
BTW Bud...Just be careful....I either sprayed or worked in garage most my life....Consultant told me post bypass...5-10 mins of exhaust fumes in enclosed space is equivalent of smoking 60 **** one after another....Stay Safe and Take Care

Sent from my iPhone using Tapatalk
 

·
Hiding under a Rock
Joined
·
575 Posts
Discussion Starter · #12 ·
The fan comes on when A/C is switched on, which is a good news - I don't need a jury rigged manual bypass fan switch.

The temperature sensor seems to be working with the dash diagnosis - the fan didn't kick in when i stopped at 105C. A/C switches on the fan straight away and brings the temperature down swiftly to ~80C, and there it goes to steady state (at idle)

So, I'm still at a loss but get by with the a/c and getting into the diagnosis mode before driving.
 

·
Hiding under a Rock
Joined
·
575 Posts
Discussion Starter · #13 ·
Hey guys - can anyone check at what temperature the fan turns on and off by going into the dash diagnosis mode pls?

Rather than randomly turning on and off the A/C, it would be good to know roughly when I should do it.
 

·
Premium Member
Joined
·
316 Posts
Hey guys - can anyone check at what temperature the fan turns on and off by going into the dash diagnosis mode pls?
Rather than randomly turning on and off the A/C, it would be good to know roughly when I should do it.
i have just run mine....took a while & a few revs lol!!....But going by dash diagnostics the fan didn't come in till 97 degrees...You won't hear it in car... I just stood outside & pushed throttle with my stick....Hope that helps....

Sent from my iPhone using Tapatalk
 

·
Premium Member
Joined
·
316 Posts
Hey guys - can anyone check at what temperature the fan turns on and off by going into the dash diagnosis mode pls?
Rather than randomly turning on and off the A/C, it would be good to know roughly when I should do it.
i have just run mine....took a while & a few revs lol!!....But going by dash diagnostics the fan didn't come in till 97 degrees...You won't hear it in car... I just stood outside & pushed throttle with my stick....Hope that helps....

Sent from my iPhone using Tapatalk
Ps....Sorry, I forgot to say...it stopped again when temperature dropped To I think 93-94....I then out of curiosity done what you done & run the A/c ....After just over 5 mins it was down to the low 70,s.....Best Regards

Sent from my iPhone using Tapatalk
 

·
Hiding under a Rock
Joined
·
575 Posts
Discussion Starter · #16 ·
Hey guys - can anyone check at what temperature the fan turns on and off by going into the dash diagnosis mode pls?
Rather than randomly turning on and off the A/C, it would be good to know roughly when I should do it.
i have just run mine....took a while & a few revs lol!!....But going by dash diagnostics the fan didn't come in till 97 degrees...You won't hear it in car... I just stood outside & pushed throttle with my stick....Hope that helps....

Sent from my iPhone using Tapatalk
Much appreciated - this will come in super handy.

yes, the fan drops the temperature down real quick, doesn't it?

I could hear it inside the car when standing still but probably not when driving because of the road noise and all.
 
  • Like
Reactions: HC56

·
Premium Member
Joined
·
316 Posts
Hey guys - can anyone check at what temperature the fan turns on and off by going into the dash diagnosis mode pls?
Rather than randomly turning on and off the A/C, it would be good to know roughly when I should do it.
i have just run mine....took a while & a few revs lol!!....But going by dash diagnostics the fan didn't come in till 97 degrees...You won't hear it in car... I just stood outside & pushed throttle with my stick....Hope that helps....

Sent from my iPhone using Tapatalk
Much appreciated - this will come in super handy.
yes, the fan drops the temperature down real quick, doesn't it?
I could hear it inside the car when standing still but probably not when driving because of the road noise and all.
Hope You Get All Sorted....If I can assist in any way I'm glad to help....Stay Safe and Take Care.... Best Regards

Sent from my iPhone using Tapatalk
 

·
Super Moderator
Joined
·
29,376 Posts
The thermostat is not fully open until 102ºC.

I would expect the rad fan to come on around that figure. It should start to open

around 88ºC though. If the engine is getting much hotter than 90 ish then you may

have an issue.

My old 2001 2L petrols fan never came on unless the AC was on, even when towing

a 1200kg caravan in August.
 

·
Hiding under a Rock
Joined
·
575 Posts
Discussion Starter · #19 ·
The thermostat is not fully open until 102ºC.

I would expect the rad fan to come on around that figure. It should start to open

around 88ºC though. If the engine is getting much hotter than 90 ish then you may

have an issue.

My old 2001 2L petrols fan never came on unless the AC was on, even when towing

a 1200kg caravan in August.
Dodgy thermostat would be the cause of rapid warmup (and subsequent overheating).

In my case, it's at least partially open - because when A/C is switched on, bringing the radiator fan on along, the coolant temperature drops down rapidly (to around 83C, which is less than normal fan cutoff point of low-mid 90s).

If the thermostat is faulty in that it does not fully open, it may not cool the coolant as much as it normally would.

But the real issue I have is that the fan never comes on, so it's either PCM or some other components.

I ran Forscan and it found no error.

I was going through the Forscan and found there is PCM reset - I wonder if it'd make any difference...
 

·
Super Moderator
Joined
·
29,376 Posts
If the thermostat is not fully opening the the engine will get hotter

but that heat wont be making it to the radiator.

The smaller coolant flow into the radiator could be cooled very quickly even

at low speeds.

The fan takes its signal from a sensor in the radiator not the main engine

temp sensor.
 
1 - 20 of 28 Posts
Top