Oil leak on W124

The car is '88 300 CE. Last year I had a oil leak repaired by dealer for about $300. Leak was located in front upper part of an engine in little rubber seal under the distributor cap.Everything was fine for a year but than I had somebody else to install new timing chain and the problem started again. The shop refused to fix the problem becouse I brought my owen parts and that canceled their warrenty. They mey be right, but they used their owen seal under the timing chain cover. The first time dealer used a black seal and they used orange one. Could use of a wrong kind of seal paste couse oil leak again? Recently I had my car servised at Mer. dealer who told me that I have a another oil leak from rear side of engine from head gasket. That news made me decide to fix all leaks in the engine area. Dealer told me $ 550 for both leaks and $400 more if I wanna do velve job. Does anybode know if this price is OK?, and what else can I replace wants the engine is apart? How long can car be in the shop for this kind of a job? Dealer offers free rental car!!
Thank for any advice!!

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'88 300 CE, SIGNAL RED
with 18" Carlson

[This message has been edited by Daniel Pawlata (edited 01-27-2000).]

[Benzmac]

Head gasket repair usually runs about $900. around here. The valve job will go up another 5-600. I think that they are off on their pricing. If the wrong sealant is used it will leak. Mercedes sealant is black.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM