Technical common problem with thermostate

[koalar]

Cool @jrkitching
I syphon to do the thermostat

Never thought about doing the whole system

One less thing to go wrong

 

[DaveMcT]

Oh dear...
I disconnected the bottom hose using the quick release connector, pushing in the two tabs top and bottom to waggle it free...
...reconnected to flush engine a couple of times...
...thought I had it fully home as I heard it click...
...got it up to temp with new coolant, no leaks, short (6 miles) drive, checked again, no leaks...
...drove home and fans came on, found coolant trickling out of the bottom hose

I have never managed to release a bottom hose QD connector. They don't feel very strong so I remove the metal band and fit a worm clip when done.

 

[rmjbn1]

Releasing the bottom hose connector wasn't too bad on mine. The old squeeze and waggle. But no, I don't think I'd attempt it again.

I replaced the bands on the top hose with jubilee clips, but reckoned the bottom quick release would be less trouble... wrong!

My 2004 1.2 has the old fashioned separate expansion tank, so I guess syphoning isn't an option to drain coolant on these.

I agree with Dave & Jock, in future I would leave the QR connector in place, remove the bottom hose and replace the clip.

 

[rmjbn1]

I think it was @jrkitching maybe on another thread mentioned a symptom of failed thermostat was increased fuel consumption?

Flippin' 'eck you're absolutely right!

Not that I ever doubted you for a moment, but I didn't expect to see much difference on mine. I though my economy was already pretty good - average consumption on computer was 56mpg (brim tests on long round trip gave 52mpg, so it's slightly optimistic). This was up from when we got the car five years ago, would struggle to reach 50mpg on the computer.

Since fitting the new stat in January, average has climbed to 62mpg according to the computer. I'm amazed! This little car just keeps getting better and better

I've learned my lesson - I'm not going to ignore it running cool again.

 

[DaveMcT]

The ECU switches to closed loop fuel injection when the engine reaches an adequate temperature. Until then, it runs open loop with a rich fuel/air setting. When the 'stat sticks open, the engine will take longer to warm up and that switch to efficient fuel metering will be delayed.

 

[koalar]

The ECU switches to closed loop fuel injection when the engine reaches an adequate temperature. Until then, it runs open loop with a rich fuel/air setting. When the 'stat sticks open, the engine will take longer to warm up and that switch to efficient fuel metering will be delayed.

These cars don't wait for the engine to coolant before going into close loop

But a scanner on and watch,

Switches within the first minute, O2 sensors are heated to speed this up

The injector timing will be effected by various sensor

RPM
Coolant
Manifold pressure
Air temperature
O2
Detonation sensor

So coolant temperature effects the injector timing

Open or Closed loop is not effected by the thermostat

 

[porta]

These cars don't wait for the engine to coolant before going into close loop

But a scanner on and watch,

Switches within the first minute, O2 sensors are heated to speed this up

The injector timing will be effected by various sensor

RPM
Coolant
Manifold pressure
Air temperature
O2
Detonation sensor

So coolant temperature effects the injector timing

Open or Closed loop is not effected by the thermostat

Yes, this is why you get different readings in different seasons and different altitudes. There was a YouTube video of someone explaining this, I think in Switzerland, on an Audi

 

[DaveMcT]

Fair enough it's got more intelligent. But a "cold" engine will affect how the ECU regulated the fuel flow. It will burn more fuel.

 

[porta]

Fair enough it's got more intelligent. But a "cold" engine will affect how the ECU regulated the fuel flow. It will burn more fuel.

I’m not sure intelligence comes into it… ‘complication’ might be more accurate…it’s a long way from ‘digiplex’ and just being controlled from ‘air mass’. My first experience being on Strada 105TC and then the leap to Uno Turbos, Cromas, Alfa 155 and 164, later Delta/Prisma’s, and the Integrale…ECUs then started to control everything…I left the trade in ‘99 so that’s the second gen Punto era end and the atrocious facelift.

 

[DaveMcT]

The boat tail narrow headlight Punto Mk2 ws a very pretty car. Fiat ruined it with a front end no different to the contemporary (and very boring) VW Polo. Whoever signed off the Punto Evo and its siblings should have been fired immediately.

 

[porta]

The boat tail narrow headlight Punto Mk2 ws a very pretty car. Fiat ruined it with a front end no different to the contemporary (and very boring) VW Polo. Whoever signed off the Punto Evo and its siblings should have been fired immediately.

Agreed, never liked (the look of) the MK2 strada, it lost a lot of character, even if the 130 was a blast…does anyone know what happened to the MK2 sporting body that was put on a Suzuki SJ chassis? Can’t even find photos on the internet

 

[kavil]

there should be a rubber gasket here. Its perished and completely gone allowing a small volume of flow to the radiator. Not so noticeable in summer but becomes more of a problem in winter. I didn't notice any MPG difference after changing but the heater was noticeably hotter

Thank you for breakdown, i was wondering as well how does it look like under the spring. dry testing the faulty thermostat underthe sink it does not allow anywater to pass otherside but apperently waterpump pressure is something different than running water under the tap.