overheating sensor??

[Flykiller]

hi I replaced the thermostat recently. Yesterday I went on my first long journey with my 01 multispace. about 2 hour journey each way.but after about 50 miles or so the temp gage shot up from the halfway point with in 3 or 4 seconds then as I let off the gas to pull over it came back down just as quick.
it then was blowing cold air. I had a look at the level in the rad and left it open for a while hoping to allow any air pockets/bubbles out.so away I went but every now and then the temp shot up real quick and as soon as I let off the gas it came down just as quick. So Im thinking its a sensor. where would I find this sensor ? is this a common problem? easy fix?
I am going to flush the system and heater core this time, I didnt do this when I changed the thermostat. No time and thought I would get away just re filling it. So any ideas?? anyone ever came across this problem?
I thank you for your replys in advance thank you ..

[Merlecollins]

I just repaced mine yesterday - absolute doddle job :thumbsup:

You can get the part from here, but check with them that it is the correct one for your model:

http://www.ebay.co.uk/itm/221102751026?s...1439.l2649

Check out these threads:

http://www.berlingoforum.co.uk/showthread.php?tid=4024

http://www.berlingoforum.co.uk/showthrea...ure+sensor

[Rustscrat]

Hi, Don't forget to fill & bleed it correctly as the the header tank is lower than the the heater hoses & thermostat. alut:

[crickleymal]

Hi, Don't forget to fill & bleed it correctly as the the header tank is lower than the the heater hoses & thermostat. alut:

That's what I was going to suggest, given that the heater went cold.

[Flykiller]

Thanks guys Ive bled the system just wondering is there just the two bleed points. A. the one above the thermostat
B. the one up at the hoses into the heater core.

Is that all of the bleed points or is there another point Im missing??

[Ol'Jeffers]

If memory serves me correctly you've done it right!

[brodfather11]

Hi flykiller ,
I'm wondering why you changed the thermostat, was it over heating ?.
A leaking cylinder head gasket can give the same effects if its leaking gases into the coolant system and it collects in the heater matrix giving cool air instead of hot. Accelerating/reving pumps more into the coolant system then easing off the accelerator pedal allows the gas to move away from temp sender to the matrix to be replaced with coolant.

Just a thought, could be totally wrong but it could mean a new head gasket required. (You dont always get oil in the cooling system)

[Flykiller]

Hi flykiller ,
I'm wondering why you changed the thermostat, was it over heating ?.
A leaking cylinder head gasket can give the same effects if its leaking gases into the coolant system and it collects in the heater matrix giving cool air instead of hot. Accelerating/reving pumps more into the coolant system then easing off the accelerator pedal allows the gas to move away from temp sender to the matrix to be replaced with coolant.

Just a thought, could be totally wrong but it could mean a new head gasket required. (You dont always get oil in the cooling system)

No it was'nt overheating just not blowing hot air. It was blowing just luke warm at best. I just bought it and in my infinate wisdom (dom being the operitive word) decided it needed to be changed. Having bled the system properly all seems good now hot air too.I have a sensor on order will replace today. So alls good now thank you all for your help:thumbsup: