Newbie - 1995 E420 w 216K. First Mercedes. Purchased as a project/extra car in a four driver family. With the exception of the front seats, the body and interior are in immaculate condition. Frequent trips between Delaware and South Carolina account for the high mileage.

I acquired this car from a retired fellow who was told he had a leaking head gasket. His symptons were occasional rough idle at startup with white smoke, occasional failure to start after running and a slight loss of compression in the # 1 cylinder. The shop he took it to diagnosed it as a leaking head gasket, but told him it was okay to drive as long as he drained his overflow tank when stopping and filled it back up prior to starting. Since the shop needed for a week and he had to be on the road, he ended up towing it home and buying a new car. After a couple of months, he ends up deciding he just wants it out of the garage and sells it to me for a minimal amount.

The car starts right up and drives fine. A few minor problems, but all in all, had he not told me about the head gasket diagnosis, I would have never considered it to be an issue. The oil is clear, cranks right up, drives better than my current car. After picking it up today, I stopped and filled up with gas about five miles from his house and it failed to start. Occasional backfire but no go. When the wrecker got there 45 minutes later, I turned the key and it fired right up.

Researching this site, I found some threads relating similar problems to the crankshaft position sensor.

Do you think the initial diagnosis was wrong and is really related to the CPS? Aside from waiting until water appears in the oil, what other test are there to indicate a leaky head gasket?

There's so many things it could be. I would start some basic diagnostics, probably at a good shop. Head gasket problems are very rare on that engine but that's quite a few miles. Not sure what he means by a "slight" loss of compression on #1 but a compression test would be a good place to start. If you have a compression issue on one cylinder that would be big news.

I am just starting out with Mercedes. I still need to do some homework and research before taking it to the shop. After suffering through the ownership of a 1995 Range Rover, and the trials and tribulations of the dealership and indies, I started doing most of the repairs myself with the help of a repair manual and sites like this. The last two cars I got for my kids to drive (Infiniti and Volvo) were acquired from owners who were frustrated by constant expensive trips to repair shops only to have the problems reappear.

My past mechanical experience was limited to the restoration of early Mustangs as a hobby. Until I spent $6k in one month for 3 trips to the Land Rover shops for the the same problem, did I ever work on a motor newer than 1976. The final straw came when one of our cars was in the shop to be repaired and serviced. When my wife brought the car home the oil was clearer but not as clear as it should be. When I returned the car to the service department, they told me the engine was worn and suggested a engine rebuild. Turned out that the jr tech could not find the filter and left the old one on. From then on I perform the maint, diagnostics and most of the repair myself, even on the our newer cars still under warranty.

I will probably start out with this car by doing a complete detail of the engine compartment checking all the connections, hoses and wiring. After reading most of the discussions pertaining to the m119 engine or the w124 chassis, I will probably apply some of the common cheaper fixes if they may apply. The reason I question the leaky head gasket diagnosis, is that the engine does not smoke consistently and there is not any consumption of oil or coolant.

Sifd324, Congrat on your new ride. Please read my post it might be helpful. Good luck on finding your solution.

1994 MB E420 issues idle/surging/stalling LONG