Have noticed a problem just this week whereby the heater blew cold for 5 seconds,then went back to warm again..... checked coolant level when cold on saturday and it had dropped by half a liter.... no apparent leaks so topped up and ran the engine with the cap off to bleed any air out that somehow might still be in there after i had replaced the td04 for a td05 last summer (hopefull i know but...) checked again today and it had again dropped a little,but not as much as before.... car again showed no visible leaks that i can detect,temp guage is rock steady as its always been,apexi commander again shows no sign of an overheating problem..... car runs perfect from cold start,id expect that any head gasket leakage might occure when cold ,ie overnight so might get a missfire on start up,but again nothing untoward..... also off boost and on boost no problems at all,everything as its always been.....no oil/water mix so cannot see it going that way either,car has not been thrashed,always warmed up/cooled down at least since in my hands,and deff since the turbo upgrade and remap...... without pressurising the system,are there any likely reasons for this problem? do these cars suffer from air locks due to the layout of the cooling system,ie no filler on the radiator itself?....or am i kidding myself and its a more serious problem?.... i find it hard to see how though as i generally drive like a granny and the car shows no signs of internal failiure??

 

If there are no external signs ....... You could try feeling to see if your carpets are wet in the front footwells .... if so it'll be the heater matrix leaking.

 

good point....... forgot that

 

These cars are also prone to air locks but I dont think they appear out of the blue.

Fingers crossed its something nice and simple to rectify!

 

it might be a very small leak...as the same symtoms happened to me ...it turned out to be the top radiator hose

 

Well the carpets are dry...... i didnt expect that to be the problem as ive had no misted windows which i would have thought a leak into the footwell and therefore damp carpets would have given me some misting up problems..... i agree air locks should not happen out of the blue,and at least several months after the last work on the cooling system was carried out,but its the least expensive option so im clutching at straws really.... will have to check the level again when i get home this afternoon and see if anything has changed or is more obvious.........

 

Could it be a slight rad or hose leak that only happens when the car is warm?

 

Possible it's a tiny hose leak which only shows itself when the coolant system pressurises and closes when the car cools down.

 

Well checked the coolant level today after driving arond for a couple of days since i last topped it up a little...... and it was still brim full in the expansion tank...... no idea whats going on unless someone has decided to syphon some out when ive not been looking lol.... why it was down under a liter or so in the first place has flummoxed me..... only thing i can think of on one cold morning on the way home from a night shift i hit an all time high boost reading of 1.41 on the power commander,normally 1.3-1.35.....wonder if that popped the heads slghtly in order to loose some coolant?..... other than that im at a loss as to explain the coolant loss originally,and the subsequent top up....... will monitor the level for a couple of weeks to see whats what.