Richy B Posted September 23, 2009 Share Posted September 23, 2009 Hi all i have a 300 Tdi truck cab, recently filled with antifreeze mix and a thermostst which was not present before, Anyhow i removed breather plugs when filling and heater on hot, run engine very good heat coming out of the heater, but the header tank is stone cols still? run for 2 hours plus and a drive round the village and further on dual carrageways, all fine no overheating or apparent temp fluctuations, th eneedle on the guage sits in the middle of the guage, but still a cold header tank ? Any clues please ?? Im guessing after such along running time with no issues its not a air lock problem? P.S the rad is only about 3 monthe old (was replaced due to it molting its fins away ) Quote Link to comment Share on other sites More sharing options...
Guest otchie1 Posted September 23, 2009 Share Posted September 23, 2009 The header tank gets its feed from the small bore pipe that runs up from the thermostat housing. Check to see if that pipe is blocked. Did you fit the stat the right way up? Quote Link to comment Share on other sites More sharing options...
mmgemini Posted September 23, 2009 Share Posted September 23, 2009 To fill a 300Tdi cooling system it must be done correctly. Heat controls to hot. Remove the plug from the thermostat housing. Remove the plug from thefiller cap from the header tank and fill to level. Refit the filler cap. Fill at the thermostat housing until water flows out of the top of the radiator. Check there are no air locks by squeezing the hoses. Make sure the coolant is to the top of the radiator. Fit the radiator plug Fill at the thermostat housing until it's full of water. Squeezing the hoses a before. Remove the header tank cap and check the level is correct. Refit the cap and run. mike Quote Link to comment Share on other sites More sharing options...
Richy B Posted September 23, 2009 Author Share Posted September 23, 2009 Cheers for the replies so far, the stat i hope is the right way round,Ie - the longer part of the stat towards the engine ? I also have a small Kinda plastic t piece off the bottom of the header tank, Whats the deal here ? is it 1 way or just a t piece ? Quote Link to comment Share on other sites More sharing options...
Aragorn Posted September 24, 2009 Share Posted September 24, 2009 I see this "heater controls to hot" quite a bit, and its something ive never quite understood... Does the defender control the flow of water thru the heatermatrix when you adjust the "hot/cold" control? On any cars ive worked on, including the disco, the heater is in the coolant loop constantly, and the control simply adjusts the flaps in the heaterbox to control the amount of air that flows thru the matrix rather than around it... Otherwise, if you went from cold to hot, or vice versa, youd have a huge lag between adjusting the control, and the output actually changing, as the matrix would have to heat up/cool down.... Quote Link to comment Share on other sites More sharing options...
DaveSIIA Posted September 24, 2009 Share Posted September 24, 2009 I see this "heater controls to hot" quite a bit, and its something ive never quite understood... Does the defender control the flow of water thru the heatermatrix when you adjust the "hot/cold" control? On any cars ive worked on, including the disco, the heater is in the coolant loop constantly, and the control simply adjusts the flaps in the heaterbox to control the amount of air that flows thru the matrix rather than around it... Otherwise, if you went from cold to hot, or vice versa, youd have a huge lag between adjusting the control, and the output actually changing, as the matrix would have to heat up/cool down.... Defender heater matrix (200/300Tdi) is the "full flow" type as you described above. Control is by setting a diverter flap to mix hot & cold air. I've never bothered with the "heater controls to hot" bit and not experienced problems with air bleeding from the matrix. It is important that the small pipe from the top of the thermostat housing to the header tank is free flowing, as this provides the circuit for coolant flow when the thermostat is closed. Flow is through the heater matrix and onthrough this pipe. Air bubbles can be seen in the header tank as the system self bleeds. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted September 24, 2009 Share Posted September 24, 2009 Heater to hot. As has been said not necessary now. Old habbits die hard. mike Quote Link to comment Share on other sites More sharing options...
markyboy Posted September 24, 2009 Share Posted September 24, 2009 From what has been said it apears that the cooling systems of the 200Tdi and 300Tdi's differ in this respect. Is that a fair statement? On my 200Tdi, the header tank is merely an expansion tank and does not form part of the "flowing" part of the system. Therefore, it never gets warm. Mark. Quote Link to comment Share on other sites More sharing options...
DaveSIIA Posted September 24, 2009 Share Posted September 24, 2009 The header shouldn't get too warm in normal operation. Once the engine is up to temperature and the thermostat opens, there will be no appreciable flow through the small pipe back to the header tank. All flow will be through the radiator. The small pipe is there to provide a bleed path for any trapped air. Quote Link to comment Share on other sites More sharing options...
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