I have a Mercedes E 300D. It was brought to me because it quit running one day. I took off the main vacuum line and it started, immediately checked the Oil pressure, it was Zero, so I shut it down. Opened the filter canister and it was empty. Oil is topped off on the dipstick. I suspected the drive chain or sproket failed. I pulled the oil cooler off the side of the oil pan, and I could see the chain is still on the sproket. Need a little help here. Is there a bypass valve the I could check. Should I have someone turn over the engine while I watch the sproket turn? I suspect the engine autoshutdown when it sensed no oil. I hope the bearings are ok. Can the oilpan/ oil pump be taken out without removing the engine? Any suggestions. Thanks