Technical Overheating?

[YodaCSmith]

Hi all
Just bought a Punto 55S N regd 63,000. I keep getting the temperature gauge warning light coming on. The garage has replaced the sensor, the water pump, the radiator but STILL it comes on - but the engine does not seem to be overly hot. The garage says it's ok to drive.

It's my first Fiat, lovely car but this is very disconcerting.
Any suggestions?
Thanks.
Yoda

 

[dave]

Hi welcome to the forum.
maybe thermostat when the engine has been running a while see if the top and bottom radiator hoses are hot if one is cold the thermostate has gone. be carefull of the fan when you do it it may come on.
AND DON'T USE THAT GARAGE ANY MORE. there are ways to check the sensor and radiator with out changing them.

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[YodaCSmith]

Thanks for the reply Dave - this one is a real mystery!

Unfortunately I bought it from them last week, so it is still under warranty - but I may pay for a second opinion. Forgot to mention that they changed the thermostat too. That was stuck open - the car was running cool but STILL the light came on.
Hoses seem fine. Can put my hand around them comfortably.

I'm not an expert on cars by any means but this is a real puzzle!

 

[dave]

If its under warenty and they can't fix it, give tham the car back and ask for your money back, whats going to happen if it does oneday over heat and you don't realise because the light is always comming on anyway, engine is going to go bang.

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[stuuyh]

you might have a blocked heater matrix,are your heaters blowing cold on warm?that happened with my 55s,the red warning light came on,i flushed the system about 4 time and it worked a treat,no more over heating

sh

 

[YodaCSmith]

Internal heater works fine, thankfully - it's bloody cold!

Got a second opinion this afternoon from a garage I used to use and trust. They did a full diagnostic and test on the cooling system. They concluded that it is entirely possible that the new sender is faulty as it comes on at the point where the engine reaches normal operating temperature. They're not Fiat people so they can't be entirely certain (and bless 'em they didn't charge me...),. They did suggest that the new sender could be the wrong one and is a sender for the cooling fan, so they possibly fitted the wrong one!
Is this possible do you think?

 

[joel]

I have kinda simular problem. How warm should the hoses be from the radioator?

My car reaches up to almost red if there is very slow traffic (it takes a while) or when running idle for about 10 minutes. I opened up the car and I could hold the hoses, I mean they were hot but not that hot that it hurted to hold them. How hot should they be? They were the simular temprature, so its not the thermostat? I changed the temprature sensor a week ago because it gave me injectorlight error all the time when the car was old. Could the new one be broken? When I drive at normal speed the temprature is halfway, that seems normal.

 

[dave]

Is your fan coming on when its in traffic, could be the fan or the sensor that switches the fan on.

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Please do not Email or PM me asking for support. Post on the forums instead. Your reply may help someone else. Thank you

 

[joel]

How hot should the car be before the fan comes on? When it was passed 3/4 it was on. Im starting to think that the thermostat is broken or the temprature sensor that i bought doesnt really work that well.

I dont know what its called in English but the "bottle" with cooleant there is two wires going to it? What is that, is it another temprature sensor? Its one on the side of the engine, that one was the one I changed.

 

[colinwright]

sounds like not enough water in system or water pump worn out.
some water pumps have plastic fins to pump the water around, others are made of steel the steel ones rust and wear down and dont push the water around enough when idling but when driving it will, that combined with the air flow while driving will keep the engine at normaltemperature, also the fan on mine cuts in just under half way but when mine didnt have it came on at three quarters and the needle kept rising the level on the bottle is not be trusted if theres not enough water in the system the level could be under the rad fan switch so it dosent get hot enough to switch on the fan when it should.

colin