Technical temperature

[bioing]

hello all

i have 1998 1.2sx punto

cylinder head gasket went last year. got it sorted and cam belt done too. since then it has been fine.

last 2 weeks or so, after about 10 mins of driving, temperature is all the way up to just under the red mark. and it stays like this the whole journey. it will fluctuate slightly, but will usually stay between 3/4 to red on the dial. it stays this hot regardless of whether am stuck in traffic or driving down duall carriageway at 70.

a couple of times i have seen the temp gauge drop down from full to half (where it should be) and stay there for 5 mins or so before rising again.

fan is working cos have heard/felt it. but its not on all the time. which i would maybe expect when engine so hot???

coollant is topped up however it is a dark dirty colour. no white gunge when i look in oil cap.

any ideas? could it just be that the temp sensor is thinking its hotter than it is?

any help appreciated!

Cheers

 

[vtec]

could be air locked cooling system, thermostat, fan switch or fuse/motor,.,.,

id start with bleeding the cooling system,
look here:
https://www.fiatforum.com/punto-guides/90237-bleeding-cooling-system-mk1-punto.html


then if thats not it, try bridging the contacts on the fan switch and see if it come on straight away.,
This is the switch, just use a paper clip or similar.,
https://www.fiatforum.com/attachment.php?attachmentid=23144&d=1168675529

if it doesnt then make sure the fuse is ok, if it is then the switch could be the problem.,.


Also while the engine is hot squeeze the top rubber pipe that goes into the top radiator, it shoud be hot-ish, and shouldnt be really hard like as if theres a lot of pressure in there, if it is then its likely that the thermostat is faulty and isnt opening properly,.,

 

[Punto.Power]

coolant is topped up however it is a dark dirty colour

Thats the part that dosnt sound right to me, i wounder if that dark colour your seeing is oil in there as vtec said try bleeding the rad could be alot of air in the system, when heater is set to warm does it blow it or is it cold air?

 

[bioing]

Thats the part that dosnt sound right to me, i wounder if that dark colour your seeing is oil in there as vtec said try bleeding the rad could be alot of air in the system, when heater is set to warm does it blow it or is it cold air?

yeah i forgot to mention that... the heaters basically dont work... some mornings am bloody freezing.. they blow plenty of air through... just pretty much none of it is warm!

 

[Punto.Power]

Sounds like either loads of air in the system witch the rad needs bleeding or thermostat is faulty they only cost no more than 13 quid out a moterfactor shop and if you fit it yourself no more than 15-20mins tops, only other suggestion i could say it is would be the water pump, but i would get those two first ones done asap or it will result in another blown HG..

 

[bioing]

Sounds like either loads of air in the system witch the rad needs bleeding or thermostat is faulty they only cost no more than 13 quid out a moterfactor shop and if you fit it yourself no more than 15-20mins tops, only other suggestion i could say it is would be the water pump, but i would get those two first ones done asap or it will result in another blown HG..

thanks for the advice... ill give them a try this week!

 

[Sei S]

Exactly same problem as you - Head Gasket replaced August 2005. Last November temp water light came on, heaters packed in, and the radiator was hot at top cold at bottom (or other way around). Bled system, redid coolant and it was all fine and dandy for a couple of months. However, happened again last month (I was worried it was headgasket had gone again, and AA said it was suspect head gasket). Took it garage, said it wasnt head gasket, it was the water pump not working effectively. Replaced that and working again now - hopefully for more than a couple of months this time!

NB - also same thing with the water - a brown/rusty red colour but not sludgey.

 

[vtec]

always take what the AA say with a pinch of salt, in my experience there not the most intelligent when it comes to cars.,.
if you rad has got air in it, which it does judging by the heating not working, then theres usually a cause for it, like a water leak or something which then means the coolant level drops and the heat makes the rest of the coolant bubble, whick then airlocks it.,
check the water pump with the engine running for any leaks, there common,., im changing another one tomorrow.,
also check the core plug behind the pump, they tend to corrode after a while, theres also the rad its self, look there for leaks, if you find one then you have teh cause of the airlock.,.,.

you shouldnt have any HG damage as long as it didnt stay over the red for too long.,.
job done.,

heres a link to change the water pump,.,
https://www.fiatforum.com/punto-guides/92606-how-change-water-pump.html

 

[bioing]

one quick question, in the radiator bleeding guide (https://www.fiatforum.com/punto-guides/90237-bleeding-cooling-system-mk1-punto.html), it says fill the header tank to top... excuse my lack of mechanical knowledge (lol) but is this just the coolant tank? and when it says top does it mean to the max line or right to the top of the tank?

cheers

 

[bioing]

well i have bled the radiator.... however NO water came out of hole behind air box... when i squeezed pipes lots came out of radiator hole... but could only hear air out of back hole????

also.. the top pipe from radiator i could tell had fluid in cos it was cold after i had topped levels up.. but bottom pipe stayed normal/empty the whole time? again when i squeezed this i could hear air coming from back hole and water came out of radiator hole.

after all this... ran engine for about 10 mins (usually this is how long it takes to get to red marker) and it was only just managing half... and i had warm air coming from my heaters!!!

do you think this may have sorted it? will take it out for long drive later to see what happens to temp.

cheers

 

[Punto.Power]

It might have.. as the temp needle would sit about the middle while the car is just sitting at idle for 10mins and with it starting to blow out warm air (for now) rules out its a faulty thermostat..

 

[bioing]

well after an hours drive to work this morning.. when in normal traffic needle sticks a touch above half way constantly. and stays there even if sitting still in traffic for 5 mins or so.

when putting foot down on dual carriageway, after a few minutes begins to rise and stays at 3 quarters... but stays there... then once i get back to normal traffic.. after a few minutes goes back down to half again.

any thoughts?

obviously its much improved. so thanks everyone for all the help! much appreciated!

 

[Punto.Power]

When you started the car up for 10mins and left it idle, did you wait and re-bleed it if (necessary) im sure it says that on the guide, i would have re-done it just to see if there was any more air in there..

 

[bioing]

no i didnt re-bleed it... but as there was no water (just air) coming from back hole i was planning on doing it again at the weekend.