Mike-evans Posted May 20, 2012 Share Posted May 20, 2012 Ive noticed over the last week that the temp gauge on my GTi is going up to the red line. Just got home from a 15mile drive and I poped the bonnet to check the coolant, I can hear the cooling system bubbling as its cooling down. I opened the cap to release some pressure and the water has bubbled up and completely filled the expansion tank Is this normal? Air lock, HG failure etc......? Link to comment Share on other sites More sharing options...
Stu Posted May 20, 2012 Share Posted May 20, 2012 Does the fan come on? Link to comment Share on other sites More sharing options...
Mike-evans Posted May 20, 2012 Author Share Posted May 20, 2012 Does the fan come on? This is something I will have to check and report back lol... When it gets upto the top of the gauge I put the heaters on hot and then that brings it back down.. Ive just gone out and checked the water and its sat just under the max mark (where its been for a while). Just wasnt sure if the bubbling noise is normal? Link to comment Share on other sites More sharing options...
Stu Posted May 20, 2012 Share Posted May 20, 2012 It's normal if it gets hot enough... water boils you know... Fan. Check. Nothing else matters yet. Link to comment Share on other sites More sharing options...
Mike-evans Posted May 21, 2012 Author Share Posted May 21, 2012 Fan doesnt appear to be kicking in. How do I confirm if its the fan or fan switch at fault? Link to comment Share on other sites More sharing options...
Stu Posted May 21, 2012 Share Posted May 21, 2012 Unplug the fan from the switch and bridge the two conductors in the connector (on the plug, not the switch). Ignition needs to be on. Link to comment Share on other sites More sharing options...
caled Posted May 21, 2012 Share Posted May 21, 2012 And check the fan fuse in the box under the bonnet. Link to comment Share on other sites More sharing options...
Mike-evans Posted May 21, 2012 Author Share Posted May 21, 2012 Unplug the fan from the switch and bridge the two conductors in the connector (on the plug, not the switch). Ignition needs to be on. Yep fan fires up when I bridge the connector - fan switch at fault? What I dont understand is how this switch being faulty will make the cooling system bubble up? is it because the coolant/water is boiling up? What temp should the fan be kicking in at? Link to comment Share on other sites More sharing options...
Stu Posted May 21, 2012 Share Posted May 21, 2012 If the fan isn't working the the water will continue to rise in temperature!! If the hose the fan switch is in is hot then it's most likely the fan switch at fault. If the top pipe is cool or luke warm then you may have a faulty thermostat. Link to comment Share on other sites More sharing options...
Mike-evans Posted May 21, 2012 Author Share Posted May 21, 2012 If the fan isn't working the the water will continue to rise in temperature!! If the hose the fan switch is in is hot then it's most likely the fan switch at fault. If the top pipe is cool or luke warm then you may have a faulty thermostat. Top hose is boiling.. I've ordered a fan switch and will be in at 3 today. Is it just a case of unscrewing it from the pipe? Will I loose much water? Link to comment Share on other sites More sharing options...
Mike-evans Posted May 21, 2012 Author Share Posted May 21, 2012 Ive just fitted the new fan switch and the gauge still goes upto the red.. The fan does eventually kick inand bring the temp back down, so Im thinking my gauge is not reading 100% correct? Link to comment Share on other sites More sharing options...
Ahmotorsport Posted May 21, 2012 Share Posted May 21, 2012 When the car is cold, take the expansion cap off and start the car up and just watch the coolant, does it bubble then? Link to comment Share on other sites More sharing options...
Mike-evans Posted May 21, 2012 Author Share Posted May 21, 2012 When the car is cold, take the expansion cap off and start the car up and just watch the coolant, does it bubble then? Nope, not from what I can see. Its hard to look directly into the coolant with the way the expansion tank is shaped, but no bubbles visible looking into the tank side on.. What else could it be? Cant get HG failure out of my head, but have no mayo substance on oil cap or dipstick..... Link to comment Share on other sites More sharing options...
Stu Posted May 21, 2012 Share Posted May 21, 2012 Better change the head gasket then. Seems to be what you want to do? Link to comment Share on other sites More sharing options...
Ahmotorsport Posted May 21, 2012 Share Posted May 21, 2012 When the car is cold, take the expansion cap off and start the car up and just watch the coolant, does it bubble then?You've already said it's not losing water, so it wont be a head gasket. Link to comment Share on other sites More sharing options...
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