Technical 169 1.2 thermostat 'bypass'?

[mjc506]

'ning All,

I'm having issues with by 1.2's thermostat - the fairly typical 'not staying at temperature' symptoms (it is meant to get to the middle of the gauge and stay there, right?).

I'm convinced its not just a failed 'stat, as it's on its third in as many months (different manufacturers), and all exhibit the same symptoms and all appear to open and close fine on the stove top. Equally, I'm getting pretty good at bleeding the system, so it's not just an air pocket somewhere

I assume there must be a bypass line of sorts to allow coolant flow without cavitating the pump while the thermostat is shut/cold? Is it possible that this could be blocked, and the resulting coolant pressure is forcing the thermostat off it's seat?

Any better ideas?

 

[koalar]

'ning All,

I'm having issues with by 1.2's thermostat - the fairly typical 'not staying at temperature' symptoms (it is meant to get to the middle of the gauge and stay there, right?).

I'm convinced its not just a failed 'stat, as it's on its third in as many months (different manufacturers), and all exhibit the same symptoms and all appear to open and close fine on the stove top. Equally, I'm getting pretty good at bleeding the system, so it's not just an air pocket somewhere

I assume there must be a bypass line of sorts to allow coolant flow without cavitating the pump while the thermostat is shut/cold? Is it possible that this could be blocked, and the resulting coolant pressure is forcing the thermostat off it's seat?

Any better ideas?

yep new thermostat needed if
you start the car from cold and the top radiator Hose doesn't stay cold for a Good few minutes
its common for the thermostat rubber seal to perish

common problem with thermostate | FIAT Panda (Mk3)

when the weather get cold we get loads of cooling issues heaters only blowing warm P0115 error radiator fans coming on fast. gauge dropping down occationly. gauge only going up 1/4 way 90% are down to a missing rubber gasket inside the thermostat. Because the thermostat is opening and...

www.fiatforum.com

make sure if you need one you order the correct one. Fiat changed the design on later engines. They look different, latter ones around 2009 have the temperature sensor built in. (electrical wires)

 

[mjc506]

Yup, been through a few new ones, seals all in good condition (not swollen/cut/missing) on removal, as they've only been in place for a few weeks! The top hose stays cold for a while then heats up suddenly, so it's opening properly, and the car heats up quickly, but the temperature on the gauge will drop while descending hills. (The gauge has never gone above half way)

Yes, I've got the older stat without the sensor.

 

[koalar]

Yup, been through a few new ones, seals all in good condition (not swollen/cut/missing) on removal, as they've only been in place for a few weeks! The top hose stays cold for a while then heats up suddenly, so it's opening properly, and the car heats up quickly, but the temperature on the gauge will drop while descending hills. (The gauge has never gone above half way)

Yes, I've got the older stat without the sensor.

what year is your car
how long before the top Hose gets hot
do the heaters get nice and hot or just warm
does the new thermostat work for a short while

There is only two hoses to the radiator. Stop either end there's no flow

Top is blocked by the thermostat which blocks the flow until it opens

inside the the thermostat there is (depending on brand) a small bleed hole. this has a one way valve. Can be tested by blowing down it

 

[mjc506]

It's an 06.
I haven't timed it, but idling from cold it's ~5mins, and goes from cold to hot pretty much instantly (not a slow warming up)
They get hot
No, each time I changed it, I'll get the car up to temp in the driveway while bleeding, let it cool down, then give it a run. It'll get up to temp quickly and easily in the drive, and when under load/low speeds, but the needle drops when descending significant hills from the start. But at least it doesn't get any worse with time haha

 

[jrkitching]

'ning All,

I'm having issues with by 1.2's thermostat - the fairly typical 'not staying at temperature' symptoms (it is meant to get to the middle of the gauge and stay there, right?).

I'm convinced its not just a failed 'stat, as it's on its third in as many months (different manufacturers), and all exhibit the same symptoms and all appear to open and close fine on the stove top. Equally, I'm getting pretty good at bleeding the system, so it's not just an air pocket somewhere

I assume there must be a bypass line of sorts to allow coolant flow without cavitating the pump while the thermostat is shut/cold? Is it possible that this could be blocked, and the resulting coolant pressure is forcing the thermostat off it's seat?

Any better ideas?

It's almost always an internal seal problem; every failed Panda thermostat I've seen will pass the boiling water test.

Everything you've posted points to this being down to the thermostat not fully sealing when it closes; the bizarre thing is that you've tried a number of different brands of thermostat with similar results.

If it works normally after the thermostat has been replaced, even for a short while, I can't see what else could be causing the problem. If the coolant is badly contaminated, it's possible the contamination could be stopping the seal from sealing fully.

Some aftermarket thermostats are known to be of poor quality, but usually even those last longer than this.

 

[mjc506]

Agreed, everything points to a duff thermostat, aside from them being new and replaced with no change in symptoms. The one I've just taken out was from Shop4Parts, but looks pristine (as it should). The coolant is new (and correct) too. I'd suspect damage to the thermostat 'seat', but that gets replaced each time too.

87°C is correct, isn't it?

Possible that the temp sensor is reading wrong? (But then it wouldn't get to the middle of the gauge, and it does always drop when off load/descending a hill, so it's not just a dodgy contact)

 

[koalar]

are you buying online
if so post a link

the fact it cools down when going down hill means coolant is entering the top Hose past the thermostat when it shouldn't rather than a faulty temperature sensor or gauge. Unless the change is sudden

 

[koalar]

Agreed, everything points to a duff thermostat, aside from them being new and replaced with no change in symptoms. The one I've just taken out was from Shop4Parts, but looks pristine (as it should). The coolant is new (and correct) too. I'd suspect damage to the thermostat 'seat', but that gets replaced each time too.

87°C is correct, isn't it?

Possible that the temp sensor is reading wrong? (But then it wouldn't get to the middle of the gauge, and it does always drop when off load/descending a hill, so it's not just a dodgy contact)

correct

 

[mjc506]

Not sure what was in the car when we got it, but it didn't look particularly janky when I pulled it out.
Then it had a Quinton Hazel stat from the local motor factors
Then 'original Birth' https://www.shop4parts.co.uk/?name=store&op=Product&ProdID=470
The one I put in yesterday is a Mapco. Definitely the worst of the lot in terms of casting quality, but appeared to seal just fine.

 

[koalar]

on the drive does it reach centre of the gauge, does it blow hot air or warm. When going down hill does it blow colder air, do you have a scanner/reader

 

[koalar]

It's an 06.
I haven't timed it, but idling from cold it's ~5mins, and goes from cold to hot pretty much instantly (not a slow warming up)
They get hot
No, each time I changed it, I'll get the car up to temp in the driveway while bleeding, let it cool down, then give it a run. It'll get up to temp quickly and easily in the drive, and when under load/low speeds, but the needle drops when descending significant hills from the start. But at least it doesn't get any worse with time haha

right bit of a delay in posts being visible
5 minuets is correct the thermostat is working correctly here
yes as soon as it opens it gets hot quickly this is normal.

 

[mjc506]

Sorry, yes, far too keen refreshing and replying haha

I don't notice it blowing cooler when going down hill, but I've got the fancy climate control so it'll correct itself somewhat I guess, and it only drops by about an 1/8th of full range.

I do have MES, but haven't taken the laptop for a drive. I'd assume that the gauge just runs off coolant temperature anyway.

Possible that the thermostat/cooling system is simply too slow by design to keep up with fast changes in engine load? There's no dual carriageways or motorways locally, so I don't know what it does at constant high speeds/flat yet to be honest. But that seems a little far fetched... there are mountains in Italy too

 

[koalar]

I don't notice it blowing cooler when going down hill, but I've got the fancy climate control so it'll correct itself somewhat I guess, and it only drops by about an 1/8th of full range.

I do have MES, but haven't taken the laptop for a drive. I'd assume that the gauge just runs off coolant temperature anyway.

Possible that the thermostat/cooling system is simply too slow by design to keep up with fast changes in engine load? There's no dual carriageways or motorways locally, so I don't know what it does at constant high speeds/flat yet to be honest. But that seems a little far fetched... there are mountains in Italy too

the work fine in the hills. Been all around Wales and Scotland

You can read the sensors live data to see if its reading wrong or displaying wrong

 

[mjc506]

Yeah, I'm not expecting real problems due to hills.

The 'drop' seems to take ~30secs I guess. I can't convince myself either way if that's too quick for a few litres of coolant or not...

Good point though, I'll take a run with the laptop plugged in, that'll give better data in terms of actual temps, rate of change etc etc. The gauge has a dead spot around the middle anyway to stop it waggling about too much, so that'll be hiding some information. That'll be next week unfortunately, I'm at the office today but don't have the ELM with me, and away all weekend...

Where is the actual temp sensor located? I can't find it on ePer.

Thanks for your help

 

[koalar]

back right-hand side if looking from the front

 

[mjc506]

Gotcha, thanks

 

[koalar]

k036

if memory serves me correct it has a green connector

will need a new hose clamp

 

[koalar]

yes it was green

cant remember how it all unclips. Everything has to be done by touch

 

[mjc506]

Ah, nice, many thanks