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Discussion Starter · #1 ·
The patient is a 57 plate.
6 months old waterpump and coolant sensor.Started to overheat at the heatwave. Just fitted new thermostat and heater matrix to have everything new. Refilled the coolant warmed it up pumped out the air the heating was working fine but after I opened the expansion tank seems like there is no flow fan comes in but doesn't cool down warning light comes up. No leaks, hoses good. It's been head gasket tested a week ago garage said it's fine.
I don't like to waste more money on trial and error and running out of ideas.
Thanks for any advice
 

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Discussion Starter · #5 ·
Expansion tank open and I was pressing the hose going to the radiator to help to push the air out.
As a side note I went for a drive and while checking the temp. Different speed and roads( 30 small streets to 60 dual carriageway) and everything ways fine. I could see the temp going down from105 to 88-94 then without any thing just gone up to 130 warning light for 20 seconds and gone down again.
 

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As a side note I went for a drive and while checking the temp. Different speed and roads( 30 small streets to 60 dual carriageway) and everything ways fine. I could see the temp going down from105 to 88-94 then without any thing just gone up to 130 warning light for 20 seconds and gone down again.
When stood still is the fan kicking in at 105c?
(may be a few degree either side)
 

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Sometimes,other times just gone up to 110 and I switched it off.
I tried to revv it once its gone up to 125 warning light switched it off.
Could be the wiring? Can I buy those somewhere?
Id think that if it was the wiring (a short or surge) then it would shoot up every time you revved the car up, my personal experience is that when a component is to blame the issues start intermittently then eventually fail. I may be wrong, but its certainly the thing that would be the first suspect.
 

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Discussion Starter · #11 ·
Update
The water in the exp. tank dropped so I refilled it. On my way to work the temp gone up over 130 then to - 40 and the oil warning light joined the party.
I feel like it's time for the scrapyard before I spend all my money...
 

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Update
The water in the exp. tank dropped so I refilled it. On my way to work the temp gone up over 130 then to - 40 and the oil warning light joined the party.
I feel like it's time for the scrapyard before I spend all my money...
There's 2 temp sensors in total i believe, one on the engine and one in the bottom of the radiator, could be one of two going or both.
 

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Hi Richard, any update on your car regarding overheating issues, I hope you haven't given up and got your car scarpered.

I had very similar issues to yours, and replaced many things like new radiator, cleaned inner heater Matrix, new water pump, removed thermostat altogether to rule out stuck thermostat, replaced engine temperature sensor, replaced reservoir bottle caps 3 times, had my HG sniffer tested, all to no avail, and in the end no one suggested having Pressure Tested my coolant system, this is where the issue was, as engine heats up the water heats up just as it does in central heating boilers, its volume increases, this creates pressure in system, as well as some of the heated water will generate vapours, so if this pressure is used to help raise the boiling point of the coolant from the normal no pressure boiling temperature of 100c, to over 116c with a pressure build up of 10psi.

You can see what happens if there was no pressure being build or if your pressure was escaping, the engine coolant starts to boil at 100c or thereabouts and starts to spew out of the reservoir Bootle, emptying the engine of coolant, until such time as there is not enough coolant left surrounding the water pump impeller, so no further coolant gets pumped out to the radiator, or through the internal heater matrix, which stops giving out heat as there just isn't any coolant circulation, whilst the engine may continue to overheat, and fans kick in when engine temperature reaches 105c, but since most of the coolant has escaped, there is no more coolant flowing through the radiator and so it has nothing to cool even though your fan may be running at full speed, and your engine continues to overheat, this happened because your cooling system had no pressure as any pressure was escaping through something, and so when engine reached 100c most of the coolant had boiled out, hence the cause of overheating.

Finally I came here seeking help, and I was glad that members here were very helpful, my special thanks to SKI_1.2 who suggested looking into coolant Pressure, or any Leaks in the cooling system from where pressure might be leaking, so I went ahead and conducted a pressure test only to find that my pressure would not build up due to defects or manufacturing tolerances in the after market reservoir bottle caps, so finally I managed to trace the cause which was the inner O ring sealing to the bottle neck, ) ring seal was not making an air tight joint to the reservoir bottle, I guess over a long period of time, these plastic bottles can warp, or deform or necks wear out causing poor pressure seal, so I temporary wrapped a good few turns of white PTF plumbing tape around the cap bottom O ring seal, the smaller of the two seal rings, and this stopped my issue, now I have ordered a brand new bottle and its own cap, original GM part for just around £25.00, This will most certainly cure overheating issues when all else have been tried and failed. Pressure testing is the key to Euro 4 cars as they tend to run at higher engine temperatures, i.e. 105c, whereas my old school Calibra would run at around 85c to 95c where pressure is not significantly important, or critical, yes it is still pressurised but its fans cut in a lot earlier i,e at 85c hence keeping coolant to well under boiling point.

Water or coolant under pressure of 10psi will boil after reaching 116c so in Corsa fans cut in at 105, thus maintaining overall temperature to well under boiling point of 116c. I hope this will help.
 

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Discussion Starter · #14 ·
Hi Richard, any update on your car regarding overheating issues, I hope you haven't given up and got your car scarpered. I had very similar issues to yours, and replaced many things like new radiator, cleaned inner heater Matrix, new water pump, removed thermostat altogether to rule out stuck thermostat, replaced engine temperature sensor, replaced reservoir bottle caps 3 times, had my HG sniffer tested, all to no avail, and in the end no one suggested having Pressure Tested my coolant system, this is where the issue was, as engine heats up the water heats up just as it does in central heating boilers, its volume increases, this creates pressure in system, as well as some of the heated water will generate vapours, so if this pressure is used to help raise the boiling point of the coolant from the normal no pressure boiling temperature of 100c, to over 116c with a pressure build up of 10psi. You can see what happens if there was no pressure being build or if your pressure was escaping, the engine coolant starts to boil at 100c or thereabouts and starts to spew out of the reservoir Bootle, emptying the engine of coolant, until such time as there is not enough coolant left surrounding the water pump impeller, so no further coolant gets pumped out to the radiator, or through the internal heater matrix, which stops giving out heat as there just isn't any coolant circulation, whilst the engine may continue to overheat, and fans kick in when engine temperature reaches 105c, but since most of the coolant has escaped, there is no more coolant flowing through the radiator and so it has nothing to cool even though your fan may be running at full speed, and your engine continues to overheat, this happened because your cooling system had no pressure as any pressure was escaping through something, and so when engine reached 100c most of the coolant had boiled out, hence the cause of overheating. Finally I came here seeking help, and I was glad that members here were very helpful, my special thanks to SKI_1.2 who suggested looking into coolant Pressure, or any Leaks in the cooling system from where pressure might be leaking, so I went ahead and conducted a pressure test only to find that my pressure would not build up due to defects or manufacturing tolerances in the after market reservoir bottle caps, so finally I managed to trace the cause which was the inner O ring sealing to the bottle neck, ) ring seal was not making an air tight joint to the reservoir bottle, I guess over a long period of time, these plastic bottles can warp, or deform or necks wear out causing poor pressure seal, so I temporary wrapped a good few turns of white PTF plumbing tape around the cap bottom O ring seal, the smaller of the two seal rings, and this stopped my issue, now I have ordered a brand new bottle and its own cap, original GM part for just around £25.00, This will most certainly cure overheating issues when all else have been tried and failed. Pressure testing is the key to Euro 4 cars as they tend to run at higher engine temperatures, i.e. 105c, whereas my old school Calibra would run at around 85c to 95c where pressure is not significantly important, or critical, yes it is still pressurised but its fans cut in a lot earlier i,e at 85c hence keeping coolant to well under boiling point. Water or coolant under pressure of 10psi will boil after reaching 116c so in Corsa fans cut in at 105, thus maintaining overall temperature to well under boiling point of 116c. I hope this will help.
I had reservoir tank change before because the previous one cracked up probably because the pressure you talking about. Its gone just after a couple of days after the post I was in need of a car to get to work so I got another car. Thanks for the tip anyway it is gonna be useful for the community.
 
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