I've posted this elsewhere (on a more "specialist" forum) but without any sensible answers, so it's worth a try here... I doubt any of you will have come across this prob but you may be able to suggest a sensible way forward.
This (my daughter's, (previuosly SWMBOs) car has been with my mechanic a number of times for this problem but we've not yet fixed it. it looks remarkably like problems reported on older Fiestas caused by a faulty heater control valve, but I'm not sure my car has one - certainly can't see one in the engine compartment, as per YouTubes...
So the symptoms. Firstly, the car will sit idling for hours without overheating, The fan kicks in correctly.
My mech plugged in his device today so I could drive for a bit and test extensively. In short:
It is definitely overheating - warning light comes on at 120 degrees. The car first went in because of steam escaping, so it isn't just a false reading.
If you then turn on the cabin heating it drops fairly quickly back to about 102 (this is on motorway driving) and stays around there, or a bit higher.
Mostly the bottom radiator hose does not get even warm during/after driving, but after one test today I left it idling with heater and blower on full for about 10 minutes (temp about 100) - temp dropped to 90.and both rad fans were pretty hot.
Both of the heater pipes were hot each time I checked them.
The temp change when turning off/on the heating when running at 70 mph is entirely reproducible.
The car has been in the family since it was 6 months old and it has never had any parts replaced or gunk added to the coolant. It has about 45k miles and FSH, mostly Ford. It used to be the wife's car so no-one will have driven it hard.
So far it's had a new radiator cap and fan (proven not working by an automotive electrical engineer!). The rad has been bled and the mech used a sniffer in the coolant tank and said there was no evidence of head damage. The coolant levels aren't going down. He advises that the pump appears to be working, the rad doesn't appear to be blocked and the hoses all seem OK.
So we are stuck. Having read other threads I've asked him to replace the heater control valve but as above, I'm not sure it has one (though I feel it must).
If that doesn't work I guess it will be a water pump then a radiator, but there is nothing else we can think of. I am trying to limit the cost too!!!
Any thoughts would be much appreciated. Either about HCVs, what to do next, or other diagnostics/tests I can do to narrow it down.
Only suggestion from elsewhere is to try taking out the thermostat and see what happens, but I'm not sure what the expected outcome would be and what it would prove.
I don't want to influence any thinking but it seem to me that the stat may not be opening. Therefore it needs a bit of thought around why this might be, if the new stat isn't duff. My pwn theory is still around the thermostat. Apparently the hot water reaches the stat from the heater outlet which is why the heater control valve is a possibility. But although I imagine there MUST be one, it is definitely not in the same easy-to-access lalce as the older Fiestas.
I'm adding this at the bottom as it may be a red herring but the AC doesn't seem to be working that well either, with vaguely warm air from the vents. I'm thinking this could be consistent with a problem in the heater area but not really sure what.
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How do you know the rad does not appear to be blocked? All the symptoms and work to date indicate it is not doing its job.
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I've experienced a t/stat stuck closed before with very similar symptoms. The little 'jiggle valve' in it would allow enough flow at tickover, but not when running.
Your symptoms would indicate a partial blockage somewhere in the system, or something else limiting flow.
I think I'd start with Zeddo's theory, remove the rad and flush it.
If that doesn't cure it, then next I'd replace the t/stat.
If that doesn't cure it I'd start thinking about the water pump. Don't some have problems with vanes braking?
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Looking at Youtube. The HCV looks to be hidden under the scuttle at the base of the windscreen so you wont see it in the engine compartment. Try looking at somewhere like Eurocarparts to see if they list one for your vehicle. That may confirm, or not, whether it has one.
You don't mention how old the vehicle is. How often has the coolant been changed does the coolant look in good condition? If its rusty coloured that could spell problems. I'm also tempted towards a blocked radiator. You can get some success by removing radiator and backflushing (bottom to top) with a hosepipe and see what comes out.
Thermostats are pennies. Why not change? You've nothing to loose.
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Thanks all so far. It's a 2011, reasonably low mileage, and been in the family since about 6 months old.
Up to a point I'm taking my mechanic's word that the rad isn't blocked. But the other day when I was testing it but driving up and down the motorway, then idling for 5 or 10 minutes, it was overheating (and the bottom pipe staying cold) then suddenly it got hot.
The stat has been changed once already, that's why I've not yet got back to it. I think you found the right version of car (believe it's Mk 7) Full Chat but I can't find the same. In earlier cars the HCV is in the engine compartment. I have found a YouTube on overheating Fiestas of the right vintage and it has a couple of easy checks of resistors and fuses which I'll also look at (but they seem to involve the fan not working, but it is).
I believe it was Eurocarparts who raised the query whether there is a valve, when the mech called them to order it. Having just spent a while on YouTube I think the flaky bit is now known as Blend Door Actuator, but this seems less likely to be the problem in the Mk7.
The car has been regularly Ford serviced so I'd hope that the coolant has been checked/changed correctly. From memory it looks OK, but I will check.
I think the fact that the coolant surface was "active" at tick-over was what led them to believe the pump is OK.
I'm going over to see him this afternoon and will ask about the rad. I wish I was more handy myself, and had proper tools and work area etc, as a lot of this is quite basic spannering and isn't far out of my scope. but as it is I am paying him quite a bit (though nothing like Ford prices!) to do the basics.
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If the rad outlet is cold after a decent run, but the engine is overheating, then it's not doing its job properly, which is down to one of three things:
1. The rad is blocked (either internally or it's got a plastic bag / excessive road muck stuck on the front of it!!)
2. The stat has failed closed
3. The water pump is knackered
The only reason the heater helps things is it is taking the place of the non functioning radiator (which would rather suggest that the water pump is OK) - the rad will have plenty of capacity to cool the engine in the UK climate on its own without the heater. A 2011 car would almost certainly have come with long life coolant, so it seems unlikely that the rad is blocked internally.
I would:
Take the stat out and test it in a pan of hot water - if it fails, fit a new one. If it passes, then run the engine and take off a bleed screw cap - water should shoot out if the pump is OK.
If it does, then you are down to the rad - there was a thread recently about a funny clonking noise on a Focus which turned out to be a radiator flap - is there one on a Fiesta, and has it failed closed?
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Thanks again all.
The thermostat has been tested OK. We did the water test in Richard's post above and water spurted out (not dribbled).
The rad is the cheaper of the two in terms of workshop time so tomorrow he's changing the rad. The pump has to have the whole cam belt etc off, so he suggested a new cam belt kit too.
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Firstly, there is no heater valve on this model . Ford stop using them in 2002. Some of these Fiesta models have an electrically operated blind system in front of the rad . If it has one , make sure it is opening. The rad should be hot all over . Best way to check for any blockage is to remove the rad and lay it flat on the floor and fill it with hot water. There should be even heat across the core . Worth a try.
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Why not run it without the thermostat? At least, that will eliminate one thing. Sounds to me like a blockage somewhere in the radiator.
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>> Why not run it without the thermostat? At least, that will eliminate one thing. Sounds
>> to me like a blockage somewhere in the radiator.
Running without a t/stat can, I've been told, create local overheating problems due to lack of back pressure.
???
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>> Running without a t/stat can, I've been told, create local overheating problems due to lack
>> of back pressure.
But surely running it with a thermostat that is stuck wide open would result in the same thing?
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An open t/stat is a smaller hole than no t/stat.
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Radiator now replaced. No change (including from a couple of hundred!!)
The thermostat is apparently quite hard to do as it requires the alternator to be taken off and it's accessed from underneath. I have the car at home for the weekend but limited technical capability/tools/time.
In the absence of any better suggestions the next step is to re-replace the stat. The only other bit is the pump which is an expensive job as it involves cambelt removal
Parts replaced so far )in order):
Fan (expensive, def wasn't working)
Thermostat
Sensor
Filler cap
Radiator and bleed cap
Other info
Car is only 2011 with 45k miles
Sniffer in coolant tank indicated no head problem
Water is "active" in tank which makes them deduce that pump is OK (at least at tickover).
All pipes seem to get pretty hot except bottom radiator one which remains almost cold (all being to/from cabin heating, top rad, connected to engine, back to coolant tank)
Temp reduction when cabin heater turned on probably a erd herring as it rose after use in that state
Aircon is not blowing v cold
No visible obstruction on front of aircon "radiator" (which sits in front of the coolant rad)
EDIT to add:
It seems that it will sit all day on tickover with no problem, though that's only properly tested once.
One time when I took it ion the motorway run to test if fixed, I let it stand idling for a while and the bottom hose got hot
Last edited by: smokie on Fri 28 Jun 19 at 13:35
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Do all the hoses look/feel good? They can collapse inside if there has been a vacuum, which happens if the circuit can't suck air/coolant back in when it cools.
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I'd read about that elsewhere. They all look OK, like you'd expect them to at that age etc.
I guess if I were to replace one it'd be the one which is cold? It's probably marginally cheaper to get my man to do it while he's doing the thermostat.
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Id have put good money on the rad. It seems you have :S
If the bottom of the rad is remaining cold then the hot water is not circulating properly which indicates the thermostat.
If the car is a keeper its probably worth doing everything properly including the cam belt. It probably needs changing on age alone.
Last edited by: Fullchat on Fri 28 Jun 19 at 13:39
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It is a keeper really except we gifted it to daughter earlier this year when SWMBO got her Yaris, and daughter is not so keen on the Fiesta as the C'eed she had before. It is generally in pretty good nick, apart from aircon and this problem. But I'm already over £500 down and no result!!
Anyway I'm just about to take it for it's MOT, fingers crossed!!!
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A good test for the HCV on the older cars was to set the heater to hot (assuming the valve works). If the overheating problem improved or went away, that was your culprit.
We had this issue on a mk4 Fiesta. We bought it on a cold, snowy day so the heater was on max, and it was OK. As soon as the weather warmed up, it started to overheat. I didn't make the link initially with the heater setting, but rather found it through trial and error. But not before I'd replaced the thermostat and flushed the radiator, neither of which made any difference at all.
It would idle all day long without overheating, regardless of heater setting. When driven, it would overheat within a couple of miles. Unless the heater was set to full hot, in which case you could drive it all day without an issue.
We concluded that there was some sort of fault or internal blockage inside the HCV that wasn't allowing sufficient coolant to bypass the valve when it was closed off. When the valve was open, coolant flowed normally.
I put a new (genuine Ford) HCV on it, and the problem went away. A huge relief at the time.
Last edited by: DP on Fri 28 Jun 19 at 14:15
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I thought Ford went to airblend heaters decades ago. Obviously not.
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Thanks DP, I'd found that issue reported earlier on t'internet and expected it to be the cause.
But, as said above, the 2011 no longer has the HCV.
I think I've mentioned that turning ion the heating to full does relieve the problem. Tested this again today, it dropped from 120 to about 90. Bu this time I kept driving and it slowly crept up again to about 111 by the time I got home, with the heater still on (not the best day for that test!!)
It passed it's MOT with just one advisory on two tyres so that's a bit of a relief.
So far it's the stat next, for the second time, before doing the expensive pump.
Does anyone know a test for the pump failure?
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>
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>> Does anyone know a test for the pump failure?
Yeah, when you put the heater on the temp drops by about 30 degrees, but then it creeps up again.
Last edited by: Zero on Fri 28 Jun 19 at 19:13
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>> Is that serious? :-)
What do you think!
Tho to be fair, the pump is the only things left, and its left because its the most expensive thing to fix.
When is the cam belt due anyway?
Last edited by: Zero on Fri 28 Jun 19 at 21:29
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Can’t see it being the water pump, they rarely fail on this model . If this were the problem , there would be no heater and no flow return to the expansion tank . The engine would overheat far quicker. Please forget any heater control valve issue . As I reported earlier, Ford stopped using these in 2002 .
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Going with the stat and maybe the bottom hose next I reckon. The car is here so over the weekend I will look at it myself and see if there is anything I can reach easily to check.
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So the coolant exits the rad by the bottom hose?
Where is the other end of the bottom hose attached?
Is there some obstruction to the bottom hose or its outlet?
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Into the thermostat housing I think.
www.bluespringsfordparts.com/auto-parts/2011/ford/fiesta/sel-trim/1-6l-l4-gas-engine/cooling-system-cat/radiator-and-components-scat
There are some thermostat housing bits with hoses for sale on eBay, so I assume there must be a demand for it. Maybe I'll get one of those to fit when he does the stat. Sensible? Or throwing good money after bad?
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The t/stat housing normally has the top hose on its outlet side. The t/stat measures the temperature of the coolant and opens when the coolant is hot. The coolant then flows into the top of the radiator (or side if it's cross flow) and the then cooled coolant flows into the bottom of the engine. The pump IME usually sits somewhere in the cooler side of the system.
There will be a bypass flow and return somewhere to the heater. The system may be complicated by coolant flow to a heat exchanger somewhere with the lubrication system and a turbo if fitted.
See: tinyurl.com/y3hwcwfa
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The thermostat on these sits in the engine block at the front , behind the plastic housing . It is in the return flow from the rad to the engine .
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>> The thermostat on these sits in the engine block at the front , behind the
>> plastic housing . It is in the return flow from the rad to the engine
Really? So it's measuring the coolant temperature AFTER it's been cooled by the radiator. What sort of temperature parameters does it have?
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No . Coolant temp is measured on the engine in the cylinder head ,via the engine coolant temp sensor through the engine control unit, and then networked to the instrument cluster.
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>> No . Coolant temp is measured on the engine in the cylinder head ,via the
>> engine coolant temp sensor through the engine control unit, and then networked to the instrument
>> cluster.
So what controls the t/stat opening and closing?
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Its mechanical. The coolant in the block reaches around 95deg C. The thermostat is immersed in that coolant and it should open automatically allowing the stgnant coolant to now circulate. Hence the sudden rush of coolant in the top of the radiator.
Last edited by: Fullchat on Sat 29 Jun 19 at 23:01
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... and the overheat light lights at 120 degrees. I know, I was there... :-)
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>> Its mechanical. The coolant in the block reaches around 95deg C. The thermostat is immersed
>> in that coolant and it should open automatically allowing the stgnant coolant to now circulate.
>> Hence the sudden rush of coolant in the top of the radiator.
I was asking carmalade, who stated:
The thermostat on these sits in the engine block at the front , behind the plastic housing . It is in the return flow from the rad to the engine.
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>>
>> When is the cam belt due anyway?
>>
...on age, 8 years.
I know 'cos we passed SWMBO's similarly-aged Fiesta on to number one son, and he is now facing a cambelt change.
As has already been noted, water pump requires cambelt to be removed, so if it's a keeper, do both.
(For obvious reasons the pump is often replaced at the cambelt interval)
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I'm not sure he didn't replace the sensor, early days, but if you mean it's misreporting that it's overheated then it isn't - I drove it with the diag tool plugged in and the temp def reached 120 then the light went on. Also the first issue my daughter noticed was steam pouring from under the bonnet.
I think I have to bite the bullet and spend another £300+ to get the pump and cam belt done. Will be mega frustrating if that doesn't fix it though...
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>> I'm not sure he didn't replace the sensor, early days, but if you mean it's
>> misreporting that it's overheated then it isn't - I drove it with the diag tool
>> plugged in and the temp def reached 120 then the light went on.
That doesn't signify if the source for both is the same faulty sensor.
>>Also the
>> first issue my daughter noticed was steam pouring from under the bonnet.
That's a bit more significant!
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>> As has already been noted, water pump requires cambelt to be removed, so if it's
>> a keeper, do both.
>>
>> (For obvious reasons the pump is often replaced at the cambelt interval)
Strongly advised to do that with the Roomster when cam belt interval came up. Additional cost was negligible.
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It's advisable for any vehicle that has a cambelt driven water pump to change it at the same time. Failed water pumps are usually the initial source of a broken cambelt.
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OK, that's what I'll do, if it comes to doing the pump.
I've decided to fit a Ford thermostat, to replace the Eurocarparts one - may happen tomorrow.
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The water pump is not driven by the cam belt on these, so to replace it would only be a job “to do while you are down in that area” . You are likely to need a new poly vee belt , as these are a stretch type with no tensioner.
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Yep I think that's what my mechanic said (re the cam belt). I'll make sure he's aware of the other one if we get that far... thanks!
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Come on! Were waiting for the next instalment.
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Haha sorry, been in Weymouth for a short break. Very nice it was there too!!!
He has fitted the £22 thermostat today. He had it ticking over in the yard when I turned u[p and it hadn';t overheated, but then it didn't for him before. The bottom hosse was hot though, which was new to me but he said it was hot before.
My break allowed for my new £4 ODB II reader from eBay to arrive, Bluetooths to the phone and seems as accurate as his £3k piece of kit!!.
I've driven it around a bit this evening and I have to say it looks promising. No long steady runs as I had a chore to do which took me round the twisties. Temp went from about 84 to 90 at times then dropped - you could pretty much see when the thermostat opened.
I did test the new thermostat and the (new) old one in boiling water and they both seem to function about the same.
Anyway the acid test is taking it from cold, running up and down the A329M a few times and monitoring it. Then doing that again the following day.
But I am hopeful.
If it does fix it, I've wasted money on a radiator (about £105 all in so not so bad) and a Europarts thermostat (about £7 plus fitting). I have the old rad and will hang onto it just in case...
Last edited by: smokie on Fri 5 Jul 19 at 20:42
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>> Haha sorry, been in Weymouth for a short break. Very nice it was there too!!!
Tell me about it, been on hols in Dorset this week myself.
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>> >> Haha sorry, been in Weymouth for a short break. Very nice it was there
>> too!!!
>> Tell me about it, been on hols in Dorset this week myself.
>>
S'funny, I be going to Darset tomorrer meself.
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>> >> Tell me about it, been on hols in Dorset this week myself.
>> >>
>>
>> S'funny, I be going to Darset tomorrer meself.
I brung the good weather back with me.
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Today's test - 15 mile blast up and down the A329M from cold. With the problem this would have lit the overheating light (120 degrees) at about 5 miles, with the cabin heating off.
Today when the temp reached 89 it then began to decline. For the rest of the run it hovered in the range 85 - 89.
So I will let it get cols again and test again but I am quietly confident.
I don't think it's possible to fit the thermostat incorrectly so it would seem to be faulty, or at best inefficient. Maybe a good reason to only buy Ford parts.
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So how much did you “save” by fitting a cheap thermostat!???
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Ah hindsight is wonderful... :-)
I know. I didn't ask for a non-OEM part but it wasn't unreasonable for my man to fit it. It could have gone the other way and been much cheaper than taking it to Ford (as it often is with an indy) but on this occasion that didn't work out.
However with it being probably a 2 hour job plus parts and VAT at Ford I don't think I'm as far out of pocket as it looks & feels!!!
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Only the cambelt to do now, then. ;-)
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Goodness you lot, I was quite happy with stuff till you came along :-) :-)
Cam belt isn't due for a few more tens of thou or couple of years though. The car may be history by then.
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I'm away at the moment, so can't check my documentation.
AFAIK, though, the 1.25 petrol is 8 years on the Ford schedule (irrespective of mileage).
The diesels may well be 10 years.
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>> I'm away at the moment, so can't check my documentation.
>>
>> AFAIK, though, the 1.25 petrol is 8 years on the Ford schedule (irrespective of mileage).
>>
>> The diesels may well be 10 years.
>>
Weren't the 1.25 10k/100k for cambelt changes?
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Glad it seems to be sorted. Did the indie supply the dodgy t/stat? If so, isn't he/she liable for all subsequent costs?
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As in "I replaced a radiator I didn't need to replace and you must pay for it"??
Hardly.
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>> Weren't the 1.25 10k/100k for cambelt changes?
>>
As I say, I can't reference the paperwork as I'm not at home.
A quick peruse of the Ford Etis site, however, says 100k, 8 years for the 1.25 (and 87.5k, 10 years for the 1.4 diesel)
Check your service book for the schedule.
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I had 10 years in mind but will check.
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Pleased its sorted. I've had several faulty replacement parts over the years. I distinctly recall a replacement condensor failing 1/3 of the way along a 90mile journey. It was like riding a kangaroo [no smutty remarks please :) ]
Should have thrown the serviceable one in the boot just in case. Lesson learned. Although there are not those sort of components that we change as a matter of routine these days.
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Many years back I had problems with a Sierra company car and it seemed to be accepted that the Ford diagnosis method was to chuck new parts at it (at the leasing company's cost) till it was fixed.
I can think that in previous jobs I've had there hasn't been any "refund" of wrong or wasteful diagnosis.
I also remember taking my own Mondeo to a Ford dealer due to a stuck-open sunroof and they wanted over £100 non refundable just to look at it.
Lastly after the first couple of visits my indy was quite happy to take a direct steer from me on the next bit to change. I can't think exactly when that started but maybe he was being canny.
Anyway, frustrating though it is, I'm glad it's now fixed and I'm moving on, as they say these days.
Future cars will still go to him for repairs/service, once over a certain (undefined) age when I consider the dealer service history to be unnecessary.And he won't touch my PHEV cos he knows nothing about electric vehicles and doesn't want to get electrocuted.
Which is a shame. because I might need a brake disk replaced before next year's MOT, and apparently they are the same as an Astra, both in parts and method. (One rarely uses brakes in a PHEV as resistance/engine braking is much higher when you lift off, but the dealer reckoned this one must have been dragging at some point).
I often wish I were a bit more mechanically minded and had better facilities/equipment. Had that been true the Fiesta would have cost a fraction and the Amp brake would do too. Ah well...
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Ford Fiesta - 11 1.25 Overheating Fiesta - Zero
