Reply To: Coolant water loss

Bob, no suggestions ….. only sympathy.

The 6 is notorious for overheating problems and I have had somewhat similar experiences over the short time I have owned mine but, unfortunately, I have no temperature gauge and must rely on visible steam as an indicator.  The weird thing is that, like yours, my problem was inconsistent and apparently unpredictable.

I know my block is completely crud-free so I had my rad checked.  This revealed a number of blocked cores, most below the wetbox and mainly resulting from previous “mends”.  Even after rodding the good cores, coolant through-flow was definitely not what it should have been so I have now invested in a reconditioned rad.  I am confident it will be much better but, due to the plague, I have yet to put it to the test on the road.

Despite my own experience in 2017, I believe the system on your car will be unpressurised and open to atmosphere via the overflow.   In that case, the fact the rad cap does not seal should make little, if any, difference.

You might check for coolant weeping at the head/block joint by cleaning thoroughly before a run and then looking for any signs of coolant leakage after the journey.

B….