Guys,

just want to bounce this off you knowledgable chaps, my heater guage gets alarming high and backs down again then abck up, only the other weekend I did a full on coolant flush, to try and resolve this, dont want to toast my engine -

heaters go hot and cold at certain intervals

video below (apologies for bad filming, better than crashing my car) -

http://www.youtube.com/watch?v=TGbhWtlAH0k


Thanks in advance chaps

 

Air in the system?
Thermostat faulty?
Fan not working?

Thanks
Sam

 

Thats quite strage mate. If it went high and stayed there I would have said the water pump has failed. But correct me if I'm wrong didn't the temp drop again.

I would go with the theremostat is going faulty.

 

thanks for the feedback guys, yes the temps up and down like a yoyo! - not sure how to right possible air in the system, is this easy? - not sure about thermostat, a fairly cheap part to replace so I'll go with that for now - fans definitely working, most of the time in fact,

 

I would first drain it and refill carefully and slowly, avoiding airlocks.

If it persists, check both thermostat and water pump.....sometimes the impellor comes loose on it's shaft, the shaft turns, the impellor doesn't, no pump

 

thanks, worth a shot, how many litres are we talking roughly? 4/5 litres?

 

Yes, but if you have a washing up bowl, you can catch most of the coolant if it's any good.

I THINK 5 litres of 50% antifreeze 50% water. That's the ratio, it's the volume I'm unsure of.

 

deffo airlock i'd say, had this on my old scooby until i got rid of the airlock

 

Try a new temp sender mate or check wiring, could be something just like a duff sender, before trying all the other things.
Jay

 

When you re-fill it remember to have the heater controls on full hot as this allows the heater matrix to fill up too

 

take the top rad hose off and fill the block side, then fill the rad side. then put top on back on and top up header tank. trick is to fill VERY slowley to allow it to burp.

 

thanks guys, I think ive got all the air out the system now, one thing I noticed the bottom (right) rad hose is cold and the top hose (left) is red hot - have I got a knackered rad?

thanks all

 

The thermostat is at the block end of the bottom hose. Does sound like the thermostat is knackered. Could also be worth reverse flushing the radiator when you replace the thermostat.

 

the bottom rad hose will always be colder than the top. otherwise the rad isnt doing its job is it!

 

How old is the car/rad - did you flush the rad, often a silted up rad will reduce its ability to cool. TBH i would take out the rad and flush it with a hose for 10 or so mins and see what comes out - also change the thermostat.

 

thanks for your pointers guys, I'll try the thermostat, first and go from there - car is 1999 - UK turbo, rad is 4 years old

 

Olly, if you run it up to temp, does the fan actually work? Would agree with Paul above on flushing the rad.

If you're driving it, I'd expect the temperature to drop as cold air flows through the radiator, the rise when your stationary.

Thermostat is relatively cheap, Mark at Import Car Parts - http://www.importcarparts.co.uk/part...Key=thermostat

Or give Alyn at AS Performance a ring, 0191 410 3770. Alyn will likely have a rad in stock if you need one.