Water Temp upto 120 degrees then back to 90??

[J0N]

Had a quick search but thought I'd ask for fresh advice.
Had a spirited run down the by-pass earlier and my water temp shot up to 120 degrees, the warning light lit up and the alarm sounded. Eased off and the temp went straight back to 90 degrees. Drove through town stopping at traffic lights etc, picked the kids up and sat ticking over and it never budged from 90. Coming home I thought I'd give it another quick go and the temp started to rise again, eased off and it came back down. Sat on the drive ticking over for ages with no problems. There are no faults logged. Any ideas? Temp sensor? Thermostat? Water pump?

 

[Binksy]

Hey JON.

You seen this thread:
http://www.seatcupra.net/forums/showthread.php?t=251809

I would say its your thermostat m8 but to be sure follow that thread and check with your climate control display "code 51c = CTS".

My money is on thermostat m8, but wouldn't rule the water pump out yet!

 

[J0N]

There is nothing out of the ordinary on the climate control display.

 

[matt-drummer]

Water pump.

 

[Binksy]

So you used the climate control display to show your CTS values ? if they still said 90 then it must be your thermostat getting stuck/sticky surly.

 

[J0N]

Water pump.

You sound sure, have you had the same problem? This has occured all of a sudden and without warning rather than a progressive problem.

So you used the climate control display to show your CTS values ? if they still said 90 then it must be your thermostat getting stuck/sticky surly.

Not sure what the climate control has to do with it mate.

 

[Binksy]

If you read that thread "all of it you would know lol"

Your climate control unit has some hidden features. you can read some internal sensors and senders one being the CTS: coolant temp Sender.

How to check this!

Accessing On-Board Diagnostic codes with climate control
Press and hold the recirculation button. Then press the manual flow control up arrow. You should see a 1c. Press the temperature up ("+") or down ("-") buttons to select a code number. Then press the recirculation button again. The value should display. Press the temperature up or down button again to display another code.

You want code 51c CTS: Coolant Temperature Sender
for a full list of codes look here http://lee69.co.uk/Car stuff/Leon/codes.txt

If that says 90's whilst your needle is not! then surly its your thermostat ? I haven't had mine go up only down. But I have had it go up in another car and it was the thermostat then so it might be in this case as long as the CTS is not going above 90s.

Go do that m8 take it for a boot and let us know then.

 

[J0N]

If you read that thread "all of it you would know lol"

Your climate control unit has some hidden features. you can read some internal sensors and senders one being the CTS: coolant temp Sender.

How to check this!

Accessing On-Board Diagnostic codes with climate control
Press and hold the recirculation button. Then press the manual flow control up arrow. You should see a 1c. Press the temperature up ("+") or down ("-") buttons to select a code number. Then press the recirculation button again. The value should display. Press the temperature up or down button again to display another code.

You want code 51c CTS: Coolant Temperature Sender
for a full list of codes look here http://lee69.co.uk/Car stuff/Leon/codes.txt

If that says 90's whilst your needle is not! then surly its your thermostat ? I haven't had mine go up only down. But I have had it go up in another car and it was the thermostat then so it might be in this case as long as the CTS is not going above 90s.

Go do that m8 take it for a boot and let us know then.

That is very interesting, I had no idea. I'm off to work soon but I'll definately give it a try tomorrow and reprort back. It's the fact that the rise and fall in temperatures are so rapid that leads me to believe it's the thermostat or a sensor at fault.

 

[Binksy]

Good luck m8! hopefully its simple

Don't work to hard

 

[LEE69]

Water pump gets my vote.

 

[Binksy]

Water pump gets my vote.

Don't curse it lol. if it is the CTS will read over 90s too so time will tell right ?

 

[J0N]

I've just had a quick play with the climate control and got the temp showing so I'll have a go on the way to work. It's having a cambelt/waterpump next week anyway so we'll get to the bottom of it either way.
Thanks for the help so far and I'll report back.

 

[LEE69]

Don't curse it lol. if it is the CTS will read over 90s too so time will tell right ?

Can't recall them ever over reading, always under.

 

[J0N]

Ok, I'm on my Blackberry so bear with me lol. Drove to work through town with no problems, got on the back roads upto about 60 mph and the temp went up and radiator fans cut in. Climate control never rose above 90, oil temp normal. As soon as I slow down the temp goes back to normal. Nothing smells hot and I've lost no water.

 

[LEE69]

got on the back roads upto about 60 mph and the temp went up and radiator fans cut in.

Went up to what?

 

[J0N]

About 110. Warning light came on and alarm sounded.

 

[LEE69]

Yeah water pump.
Or could be a closed thermostat, chances are it's the pump.

 

[andycupra]

to me it sounds like water pump

if you do use the climate control info and find that there is a discrepancy between the temperature of the gauge and that on the climate control then this would indicate a sensor issue not the thermostat.

If they are both the same and its over temp, (which i suspect it will be) then this would indicate that the coolant is not circulating correctly, leaving you two possibilities. Ie water pump or thermostat.
My money would be on the water pump given that it seems to depend on the driving conditions whether it goes over temp or not,

oh and the water pump issue is not unheard of, many will say very common. I wouldnt say its very common, but its fairly well known issue where the impellar (which is plastic) fractures, so the pump runs but its ability to move coolant around is seriously reduced.

 

[dan boy]

Had a quick search but thought I'd ask for fresh advice.
Had a spirited run down the by-pass earlier and my water temp shot up to 120 degrees, the warning light lit up and the alarm sounded. Eased off and the temp went straight back to 90 degrees. Drove through town stopping at traffic lights etc, picked the kids up and sat ticking over and it never budged from 90. Coming home I thought I'd give it another quick go and the temp started to rise again, eased off and it came back down. Sat on the drive ticking over for ages with no problems. There are no faults logged. Any ideas? Temp sensor? Thermostat? Water pump?

hello mate mine did the same .mine was water pump .it started like yours then just went

 

[Binksy]

Can't recall them ever over reading, always under.

Maybe it don't go above 90c on the CTS then you would of thought it would/should though

Ok, I'm on my Blackberry so bear with me lol. Drove to work through town with no problems, got on the back roads upto about 60 mph and the temp went up and radiator fans cut in. Climate control never rose above 90, oil temp normal. As soon as I slow down the temp goes back to normal. Nothing smells hot and I've lost no water.

Maybe the CTS reading doesn't go above 90c which is a shame if that's the case as it would help diagnose issues like this :< Might be the water pump then if you're getting it done in a week or so let us know if it cured it. For the sakes of £7ish you could get a thermostat fitted it will be cheaper at this point than getting it done at another.