Help ! 300tdi Gushing Coolant ..

[dogdog1]

Hi All , Fitted the new radiator , hoses , and thermostat to my project 300tdi 110 today . Filled with coolant via the expansion bottle to correct level with bleed bungs out , squeezed top hose til no more bubbles and replaced bung , topped up thermostat housing and replaced bung . Then I fired it up and thought it might be an idea to leave the bottle cap off to aid clearing the air out of the system , but within a few minutes the coolant came right to the top of the bottle , I replaced the cap and switched off the engine , a minute later the coolant was forcing its way out of the bottle and when I released the cap about a liter of coolant gushed out . Anyone got any ideas on this ?

[PAT303]

Remove the heater matrix outlet hose and reconnect when coolant flows out of it when filling the header tank,also disconnect the thermostat bypass hose and check to see if the housing is full.My guess is you have air in the system still. Pat

[BathurstTom]

Take the tank cap and the two bungs out - 1 in the radiator and 1 in the thermostat housing. Fill the radiator via the radiator bung hole until it is full and then replace that bung. Slowly fill the thermostat housing and replace the bung. This will overfill the expansion tank. Remove excess and replace cap. Run up to temp, allow to cool a little, remove cap and check level. Top up if necessary.


I have just replaced the head and this method works well (not the first time I have used it). I did as above on Tuesday afternoon and it is all good.

Tom.

P.S. ensure heater is on to circulate it there too!

[dogdog1]

Take the tank cap and the two bungs out - 1 in the radiator and 1 in the thermostat housing. Fill the radiator via the radiator bung hole until it is full and then replace that bung. Slowly fill the thermostat housing and replace the bung. This will overfill the expansion tank. Remove excess and replace cap. Run up to temp, allow to cool a little, remove cap and check level. Top up if necessary.


I have just replaced the head and this method works well (not the first time I have used it). I did as above on Tuesday afternoon and it is all good.

Tom.

P.S. ensure heater is on to circulate it there too!

Tried to follow this advice today but the engine will not warm up at idle , could place hand on side of cylinder head for a few seconds and all hoses cold but pressurized . I'll remove the fan tomorrow , if it still won't warm up I'll have to revisit this when I have it otherwise roadworthy and can take it for a run .

[jboot51]

Sounds like you had an air lock.
The 300 tdi takes a good 15 minutes or more to heat up at a fast idle without any load.

[BathurstTom]

As said above, it takes a while to warm up. It helps if you put a/c on and cover the grill for a while so it restricts the air flow. And don't forget to move your heater temp control to hot so that you get full circulation.

I just re-read your post, you should not have all hoses pressurised if it is still cold - do you have a correctly functioning thermostat?
Tom.

[schuy1]

There is no tap in the heater circuit on a 300TDi or a TD5 either for that matter. They are a contin flow only the airflap diverts airflow through the matrix or bypasses it for heating or cooling. Removing the top heater hose while filling can help, although I have never needed to. Just follow the "coke bottle" fill method and ya cant go wrong!
Cheers Scott

[loanrangie]

Pressurised hoses = gasket and or head knackered.

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[dogdog1]

Hi, got it up to temperature on the gauge today minus the fan , looked like it would have continued to rise too . All hoses were cold but pressurised , radiator and air from heater also cold . The thermo is new . Loosened the tank cap very carefully and avoided the splurge but as I did so I could hear and feel a right bubbling in the tank as the pressure escaped . It had filled itself up again of course . The coolant in the rad had dropped by a couple of inches and I could not see any in the thermo housing . Ideas ?

[loanrangie]

Do you know the history of the motor ,gasket and head ?
If its the original head my bet is on it being cracked.

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