HI everyone.
Trying to resolve a mystery. Over a year ago our P38 2.5 diesel 1999 had issues with exhaust gases leaking into the cooling system so replaced the head gasket. The car has been excellent, pulls and drives the best it has ever done. Just lately we noticed slight over flow from the expansion tank. Not a lot (about an inch in the bottom of an old pop bottle connected to the overflow pipe) over two/three weeks. The engine shows no sign of overheating even through the hot summer weeks. Did the sniff test - the blue dye turned slightly green after a while. Have checked the torque on all the head bolts and they are all the same. Done the compression tests - cyl 1 =27bar, 2=27bar, 3=30bar, 4=27bar, 5=27bar, 6=28bar. The readings are good for a 24 year old engine. Now trying to work out the next strategy - tweak the head bolts??? - put in some steel seal head gasket repair stuff.
Any suggestions would most appreciated. Cheers Mike

Replace the header tank cap for starters, then see if it is still spitting it out.

Have just replied on the dark side then saw this. +1 on the cap.