Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
There has been a service bulletin for that type of concern. Here is what it states.
19 08 14 (NNN) NNN-NNNN4
November 21, 2008.
Supersedes Technical Service Bulletin Group 19 number 05-03 dated April 8, 2005 for reasons listed below.
19 Coolant Leak or No Heat in Passenger Compartment From HVAC
|Customer concern of loss of coolant, but no leak in cooling system can be found. |
|-||Customer concern of no heat or noticeable drop in heat output in passenger compartment from HVAC system when engine at idle. |
Both concerns may be caused by a coolant leak from plastic plug.
Plug is installed in engine cylinder block near connection for thermostat housing (arrow).
Improved Coolant Plug.
Other than loss of coolant, a leaking plug can cause air to enter into the cooling system and reduce the effectiveness of the passenger compartment heating system.
32 degree F / 0 degree C ) (see ElsaWeb Repair Manual, Engine Mechanical, 19 Engine Cooling, "Cooling system, checking for leaks").
Tip: The leak from this plug usually occurs only when the engine is cold (below 32 degree F / 0 degree C ).
If cooling system is tested for leaks with engine warm or hot:
|-||Leaks from this plug may not be detected. |
Tip: Coolant leak from this plug can be sometimes misdiagnosed as a leaking coolant thermostat housing. Always carefully inspect suspected areas to detect the actual source of the leak.
|-||Carefully inspect area where plug is located. |
If the plug is found to be leaking:
|-||Remove and replace the plug.-> Required Parts and Tools |
|-||Remove sound insulation below engine. |
|-||Drain coolant (see ElsaWeb Repair Manual, Engine Mechanical, 19 Engine Cooling, "Cooling system, draining and filling"). |
|-||Remove upper engine cover. |
|-||Unfasten coolant reservoir and move to aside. |
Electrical connector of coolant level sensor must be unplugged.
It is not necessary to remove coolant hoses from coolant reservoir.
|-||Remove oil dipstick bracket bolts (2x). |
|-||Carefully remove upper dipstick tube (orange plastic |
Ensure that the O-ring on lower steel tube is not lost when tube is removed).
|-||Remove bolt from plastic plug. |
|-||Remove plastic plug from engine block. |
|-||Install a new plastic plug and secure with bolt to engine block. |
Fastener torque = 23 Nm .
|-||Reassemble dipstick tube and coolant reservoir. |
|-||Use the VAS 6096/1 to refill and bleed the cooling system (see ElsaWeb Repair Manual, Engine Mechanical, 19 Engine Cooling, "Cooling system, draining and filling" for details and approved coolant antifreeze). |
When refilling engine with coolant:
|-||Always ensure that any trapped air is bled out of cooling system (including heater core). |
|-||Recheck for leaks on cooling system (see ElsaWeb Repair Manual, Engine Mechanical, 19 Engine Cooling, "Cooling system, checking for leaks"). |
|-||Reinstall sound insulation below engine. |
|-||Reinstall upper engine cover.|