please can anyone help!!! A6 No heat

[jlaspire]

Hello! Ive spent the day in the rain trying to get all the air out of the cooling system as the heating is only blowing warmish air at higher revs! Its seems after all my efforts i still havent solved the problem! Im now worried that the cooling system maybe under to much pressure as the heater hoses are hard as rock when the car is warm! Are they supposed to be this much and will the coolant header cap realease any major pressure or could i damage the engine??????? car is a 1.9tdi 115

[MHtech63]

hi jlaspire, is the engine heating up properly, coolant gauge should reach 80 degC within five minutes or so, my the thermostat went failed open which ment the heater didn't work properly. you had to drive for about half an hour before it would give proper heat.

[jlaspire]

Hello! Thanks for the reply! It does seem to take a little longer to warm up! Ive just read on a forum if the top heater hose goes rock hard its caused by exhaust gases getting in to the coolant system and prob the head gasket! JOY! I think i will have to get the garage to test the coolant see if its true!

[zollaf]

the usual sniffer test, using a blue liquid that turns green/ yellow if exhaust gas is present in the cooling system is very unreliable on a diesel, usually not turning colour. try this, remove the cooling system filler cap and start the car. if any coolant is blown out, its a head gasket. if not, run the engine and see if any bubbles come into the tank. you can fill the tank right to the brim to make it easier to see.

[jlaspire]

Ive been on the car all day and didn't notice any of what you said but i will check again! Should i do all this from cold? Just to add someone advised me to put in radweld which i did and it made the problem worse as it made loads of bubbles and foam in the system? is that normal?

[jlaspire]

just to add the car has not been over heating and is running fine!

[zollaf]

radweld is useful if you spring a leak miles from anywhere and need to get moving. i would advise now emptying the cooling system and flushing it as radweld has a nasty habit of blocking heater matrix's. you can do the above tests from cold, but also do it hot, being very careful when you remove the cap. if youve done all that with negative results, it could be a water pump or thermostat.

[jlaspire]

Thanks! I will go and try them! I have to drive the car to work in the morning but im worried about the amount of pressure it gets when warm! Will the header tank cap blow this off if it gets to much or if it more possible it will damage the head gasket if its not already that?

[nevo]

No way put rad weld in,first thing to do is change the stat,get a vag one as they locate in the cover better,than a cheaper version,you say its pressurising up !is it blowing coolant out of the safety valve ??? when you drive it to normal temp is the header tank warm ??? could be the water pump they have a habit of the plastic impeller coming adrift of the shaft and will skip along at a much slower rate than the car revs leading to some weird temp fluctuations and head scratching, and in some cases it will completely break in half giving a total failure of cooling, a pump change requires a cam belt change so eliminate the stat first,PS is the car actually overheating,dont rely on the temp gauge,

[jlaspire]

Hello nevo! No the car is not overheating! The problem started by loss of heating and slight drop in coolant. then when i took a look at it i noticed alot of air in the system so today ive drained that off at the heater core intake! got all the air out so i thought but after test drive the top radiator hose is solid and the cap on the header is blowing off air and still no heat! I did notice water pumping out of the heater core valve more so on revs when i was taking the air out!