Technical Fiat Punto Engine Temp staying very low + poor MPG

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Technical Fiat Punto Engine Temp staying very low + poor MPG

BobbyOLeary

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Hey guys,

I'm an owner of an Mk1 Fiat Punto 60sx (1242cc), had the car for the last 4 years but the thing is 11 years old (1999 reg). Had a few problems over the years but replaced them all myself (timing belt, water pump, head gasket, catalytic converter).

The most recent fix was due to my own ineptness. I had the car filled with water after the head gasket change about 7 months ago and had forgotten to change it to proper coolant. Cue the snowfall over Christmas and my car froze over completely. I tried starting it one day and shredded the timing belt as the water pump was frozen. The freezing also pushed out two frost plugs, one below the inlet manifold and one conveniently located behind the flywheel.

I replaced both with new parts and put the car back together and filled it back with coolant and performance wise it runs just like it used to. Two problems have come up though, it now runs quite cold (lower than the first quarter on the dial) and stays there consistently. Concurrently I've seen a big drop off in the mpg I can get. When I bought it I could get up to 400 miles on a well driven tank and now I'm down to about 250 on the same tank. I had guessed damage from the freezing but the engine runs perfectly? I'm stumpted by this.

Apologies for the long message but I wanted to include as much detail as possible! Anyone seen anything like this? Probably the first thread where a Fiat Punto is complaining of running too cold!

Cheers,
Bob.
 
Couldn't this be something to do with the thermostat?
I admire you for being able to carry out some serious mechanic work, but how on earth do you do that and then fill the car with water ? ! You must be really kicking yourself for that one. Good luck in getting it sorted mate.
 
It will almost certainly be the thermostat stuck open. Its making the engine run cold so the ECU is running a rich fuel mixture. A new 'stat should sort it. Dont forget to properly bleed the coolant system.
 
Stuck open thermostat by the sound of things. Get it sorted, since I know from first-hand experience that it can knacker the head gasket. Admittedly, not as quickly as a stuck-closed thermostat will, but the constant temperature fluctuations will knacker it.
 
Thanks guys, and yeah, I was pretty angry with myself once the snow came. Lucky enough not to have damaged the engine though!

On the thermostat, is it really that simple? I'd have assumed (wrongly perhaps) that the engine would eventually heat up and that the thermostat was only there to allow this to happen quicker? Wha tI had thought was that the thermostat would stay closed until the engine got to a certain temp and then open up, I guessed that it would heat up eventually with or without a thermostat.

All that said I'll replace the thermostat this weekend and see what happens! Thanks guys, this forum is a great resource for anyone with an old Punto.
 
The thermostat is not just an on-off device, the opening is proportional to the coolant temperature. This time of year, the radiator is more than capable of over-cooling the engine.

My problem was that I was doing a lot of motorway miles, lots of cold air flowing through the radiator, and due to the shortness of fifth gear, head-gasket killing high revs on an engine that never reached operating temperature.
 
The thermostat is not just an on-off device, the opening is proportional to the coolant temperature. This time of year, the radiator is more than capable of over-cooling the engine.

My problem was that I was doing a lot of motorway miles, lots of cold air flowing through the radiator, and due to the shortness of fifth gear, head-gasket killing high revs on an engine that never reached operating temperature.

Cheers never knew that, I thought it was simply open/close! I've replaced the thermostat before (same time as head gasket as I orginally thought it to be at fault) so I know it's an easy job. I'll get it done at the weekend when I can get near a socket set. I'll report back, thanks again guys.
 
Hello,
Please forgive my late intervention on this thread. It happens that I have the same problem today (Fiat Punto). Could you confirm that replacing the thermostat eliminated the problem?
Thank you.
 
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