I have just changed my anti-freeze and flushed the system on my 2004 2.0 HDI 110 estate. These 406 models do seem to vary and the Haynes
guide did not help me that much. The following guide may help others with this particular model.
1. Remove expansion tank cap
2. Place large container under rad to catch old antifreeze
3. Remove engine cover
4. Loosen large top rad screw
5. Remove (blue) bleed cap on thermostat housing
6. Remove heater matrix bleed screw (last of 3 screws to undo on this model)
7. Remove bottom hose leading from rad to engine below the thermostat housing. This is located mid bottom of rad on this model – there being no drain plug or other means to drain the old antifreeze. Having removed a securing clip, I carefully levered out the hose with a screwdriver. This hose also marries up with a smaller hose leading to the reservoir tank.
8. Environmentally dispose of water drained so far.
9. Remove top rad hose by undoing the securing clamp. (I replaced the standard clamp with a jubilee clip).
10. Insert garden hose pipe into top rad hose inlet/outlet and flush
11. Ditto with expansion tank/reservoir.
12. Undo bracket (10mm nut) holding hose near thermostat housing to aid access to latter. Slide bracket forwards along large hose until job done.
13. Remove 3 thermostat securing bolts.
14. Lift off thermostat housing lid which is attached to the top hose mentioned above.
15. Remove old thermostat and test/renew.
16. Flush coolant through the block by putting the garden hose into the thermostat housing orifice with the thermostat removed. .
17. If renewing thermostat, fit rubber gasket using the old thermostat for guidance on fitting.
18. Replace hose (with lid attached) to thermostat housing and tighten bolts.
19. Refit bracket
20. Reconnect top rad hose
21. Reconnect bottom rad hose. NB I gently hit the hose with the side of a rubber type mallet because the hose needs to be fully reinstated or it will leak.
22. Jack up car on driver’s side to help stop air from entering the system.
23. Use a makeshift header tank made of an old bottle/container with a suitable neck which fits snugly into expansion tank (I used plumber’s tape to make a seal).
24. Pour in new anti-freeze until you see it emerging from the top rad screw. Make sure that exiting coolant is bubble free before tightening the screw.
25. Continue pouring until the same thing happens on the (blue) thermostat screw
26. Finally check last bleed screw on the heater matrix in the bulkhead.
27. Continue filling up
28. Star engine and run for up to 45 mins (depending on revs used – max 2000) getting up to operating temp of about 90 degrees. Add more coolant as needed and keep an eye on the level in the makeshift header tank. With the engine running you can see bubbles rising in the header tank.
29. After the new coolant stops going in and bubbles stop forming, drain off excess coolant. Remove header tank and replace reservoir cap.
30. Drive the car making sure that it does not overheat. Then for next few days keep an eye on the coolant level before driving.
PS I found that the amount of antifreeze to fill up with was 7,5 litres against the official system capacity of 8.8. I put this shortfall down to old antifreeze still being retained in the block. (Haven't a clue where the engine block drain plug is and there may well not be one at all!) The last time I did this task I put in only 5 litres of anti-freeze mixture thinking (wrongly) that I had done the job. I have read site comments from some who say that they do the job “no probs” with the car “on the drive” without jacking up the car or using a header tank etc but the key to whether the job is done is arguably how much anti-freeze mixture you have put in. I have also learned the importance of regular changes of anti-freeze because of the key corrosion inhibitor role it plays. I also prefer to use distilled water rather than tap water which possibly contains elements corrosive to the system components.
Thinking of changing anti-freeze before winter?
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