first - for CRD issues post over in 'CRD...Love that Torque' it the main diesel section
second - 2007 CRD is not in the US - the advantage everyone else has is that normally the Dealerships understand diesel - guess that's only an average and doesn't include everyone.
normally the safest approach on a broken glow plug is to pull the head. there should not be any damage and you just have a machine shop remove the plug pieces - that what my dealership did when they broke a glow plug probably 6-8 hour labor - and a head gasket.
some folks have tried to pull an injector and use compressed air to blow out the pieces - under the right conditions that can work.
breaking a glow plug by itself - should not damage the head - only if you started it with the broken parts in there - would the head be damaged - which - if you really started it with a broken plug you may have serious damage and then $6500 from a dealership sounds about right.
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2005 CRD
stuffSkeptic quod gratis asseritur, gratis negatur