Technical Engine Temperature cool. Thermostat fault?

[AILURUS LAPIS]

2009 Multijet Diesel at 137K miles.

Have noticed that the temperature gauge is not getting as hot as it use to.
Plugged in a OBD scanner and went for a drive with live water temperature showing.
At 5 miles it was up to 55C with air temperature at 7C.
After 15 miles and some firm driving up a hill in 3rd at 3.5k revs it reached 72C max.
Dash temperature gauge is showing a little higher than the scanned reading.
But not going up to the expected 90C mark.
Normal driving results in the temperature dropping to 65C.

AM assuming that the thermostat wants changing?

Any thoughts / helpful tips before I change it?

Thanks. Ailurus Lapis

 

[The Panda Nut]

In short yes. Shop4PArts original birth thermostat is cheap and good. and should sort it. Fiddly to do without removing the battery and battery tray but not hard. The worst bit is l=bleeding the air afterwards.

 

[koalar]

95% of the time, gauge not reaching halfway in the first 10 minutes (without the blowers on max) of diving it's the thermostat

Test as per here

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

The bottom of the hose radiator top hose should stay cold for the first couple of minutes then engine started

If it's getting warm instantly you will need a new thermostat

 

[AILURUS LAPIS]

If it's getting warm instantly you will need a new thermostat

Will check this first, but all the clues are there.

Will take photos and post a technical guide after it is changed.

Thanks. Ailurus Lapis

 

[jrkitching]

95% of the time, gauge not reaching halfway in the first 10 minutes (without the blowers on max) of diving it's the thermostat

Yep.

Been there, done that.

 

[ultrasonic]

Just changed mine recently after about 38k miles. They fail slowly and start opening up at lower temperatures. They are relatively inexpensive and definitely worth replacing when you flush/replace your coolant (supposedly every two years or 24k miles).

There is a brand that sells only the spring with the thermostat element fitted with a rubber seal (common ones do not have a seal) and you get to keep the housing. Haven't tried it though to see if it lasts longer.

 

[AILURUS LAPIS]

Just changed mine recently after about 38k miles.

Petrol or Diesel engine?

So mine has lasted a little longer mileage wise then.

Thanks. Ailurus Lapis

 

[ultrasonic]

Petrol or Diesel engine?

So mine has lasted a little longer mileage wise then.

Thanks. Ailurus Lapis

Petrol.

Mine was an after market one (good brand though). I've heard they can start failing much earlier (some may last only a year) so I guess picking a decent brand matters.

Edit: sorry, I missed the part where yours is a diesel one.

 

[koalar]

Follow the link in post 3, with photos


It's normally the rubber seal that disintegrates, not helped by not changing the coolant on schedule, once it acidic, changing the thermostat without changing the coolant, it isn't going to last long


Some replacement thermostats are know to be dodgy febi seem particularly bad

 

[AILURUS LAPIS]

Follow the link in post 3, with photos

Will do, although mine will be slightly different being a Diesel.

Thanks. Ailurus Lapis

 

[DaveMcT]

Just remove the battery and tray. It's only a few minutes but makes the work so much easier, you'll probably complete the job faster.

 

[AILURUS LAPIS]

Thermostat now replaced.
Temperature rising to 92C now.
Engine warming up faster and hotter.
Guide posted with photo's
Thanks for the help.

Thanks. Ailurus Lapis

 

[DaveMcT]

Mrs Dave's 1.2 is running well, coolant level is normal but over long journeys (twice recently) it's thrown up a coolant fault light. The second time, she saw the temperature gauge drop then come back up. She checked the coolant level and found all was well and the heater had kept worked fine when all this happened. I replaced the thermostat some years ago with one from Shop-4-Parts. Probably less than 5 years old.

But it does a lot of short runs so I've just ordered a new thermostat, which comes with a temp sensor. Access is so bad it looks worth changing the 'stat and cost is actually cheaper (from S4P) than just the sensor alone.

 

[DaveMcT]

I replaced the thermostat (annoying job) and found a gritty deposit (precipitate?) inside the housing. It was probably holding the valve off its seat. Coolant flushed and replaced so we will see how it goes.