If new seals fix the problem only for a short time, the guides are shot. They can also be checked for clearance when the seals are being replaced.

A valve job on a 380 can be VERY expensive due to damage to the threads in the block when the headbolts are removed.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!