As the time draws near to pick up my 560 SL I have recanted the story and the events surrounding my Head and Valve job.
I am anxious to get the bill, what do you guys think I have in store for me this PM when I go to Pick Up the car?
July 1, 2003 through July 15, 2003
Mercedes Benz 560 SL VIN # WDBBA48DOJA080494
The following information Re-Caps the problems experienced with my Mercedes Benz 560 SL at the Mileage of 124,000 miles.
The car was purchased from the previous owner in August of 2001. (74,000 miles) At the time of purchase, the car ran amazingly well, and the only issue was that it consumed a Quart of Oil every 400 miles. When I say it ran well, I mean that it had excellent power, idled at 500 RPM exactly, response to acceleration was terrific. The car appeared mechanically sound with the exception of the oil consumption.
After purchase the car was taken to three different shops to determine the best mechanical service for this type of automobile and the quality of the shops and mechanics that I met and discussed items of mechanical relevance. Based on these interviews and checking/verifying the responses with the Mercedes Shop .Com Web Site I ultimately chose Hunt Valley Imports. His reputation was good and he seemed honest.
Prior to this determination of repair shop, I replaced the Engine Oil and filter, Drained and Flushed the Cooling System, Drained and Flushed the Transmission, Drained and Flushed the Rear End. All Filters including the Gas Filter were replaced. The muffler exhaust system was replaced and the car was tuned up with new plugs, valve cover gaskets etc. All hoses for the Cooling System were replaced, the Heater Assembly that allows heat over air conditioning and vice versa was replaced. The State of Maryland required pollution tests and the car passed with nothing abnormal.
In the Fall of 2001, the Valve Seals were replaced by Hunt Valley Imports. The Seals were done to eliminate oil consumption. The seals were replaced without disassembling the Head . Following that Service, the car ran exceptionally well, NO oil consumption and other than Brakes, Calipers and Tune Up no major service was performed. Follow On oil changes have been done at 3000 miles or less.
In July of 2003 the mileage had reached 124,000 miles and as the Timing Chain was checked at each service it was determined that to avoid any problems with the car the Timing Chain should be replaced. As one can tell I drive this car about 25,000 miles per year. The Chain was done on the basis of Preventative Maintenance to avoid highway break-downs.
The car was delivered to Hunt Valley Imports on the morning of July 1st for the Chain Replacement.
At 3PM on the following day I received a phone call from the owner/mechanic who informed me that following the chain replacement, when the car was started, a terrible Top End racket occurred and they immediately shut the car down and pulled the Head on the Passenger side. This was done to determine the basis of the noise, which was assumed to be a Bent Valve. (In most cases the left bank passenger side valves bend if a chain is installed improperly) On checking the Valves the valves were determined not to be bent, but two of the valves were higher into the Hydraulic Lifter than specification. The Head was examined and it was determined that the Valves in question were not bent but that the 2 Valves in question (I believe them to be exhaust valves) showed signs of being burnt. One of the Valves at the base had hairline cracks around the circumference. As well, it was pointed out that the “Lashes” for the 2 Valves in question were thinner than all of the others and that this indicated that someone at some time must have replaced the “Lashes” to accommodate a faulty Valve/engine problem. This problem is unknown and cannot be defined as to Why it would have been done in this manner. Some discussion has taken place that the Valves in question had worked their way into the Head doing damage to the passenger side Head. This is unconfirmed.
The summary of this event is that the Head was sent to Morris Machinist in Manchester, Md. Who redid the Head replacing the 2 Valves in question and (SUPPOSEDLY) cleaning and evaluating both Heads for wear and issues. All of the Valve Guides were said to be within specification with the exception of the two at issue. These guides were replaced on those two valves only. I asked about replacement of all Guides and was told that it was not necessary. The Machine Shop indicated that Seals would be installed by Hunt Valley on all Valves. The Machine Shop comments on Head evaluation was that the car appeared to be running lean for a minimum of 15,000 miles to cause Valve damage to the extent that was obvious.
The conclusion here is not obvious. How can a V-8 Mercedes Engine run as well as it did prior to the chain replacement if these problems have been uncovered at chain replacement?
Why would the car be running “Lean”? How is that set up and how do you tell that? Again the car ran exceptionally well.
What do the different size Valve “Lashes” indicate? Are they indeed the basis of the problem? Is this solution that might be generally performed as a stop gap measure by a knowing Benz mechaic?
What does chain replacement do to affect all of these things described? Is there any fault here with Hunt Valley Imports or was this a problem waiting to happen?
These are the undefined issues that keep this writer awake at night.
I polled the Internet site Mercedesshop.com at every step of this process listed above and received back comments that implicate the Shop for not setting the timing or hand rotating the chain prior to completion of the chain replacement. However, this opinion is daunted due to both Hunt Valley and the Machine Shop indicating No bent valves? Most stated that in years of dealing with the 560 SL V-8 they have never done a valve job at 124,000 miles.
This is a mysterious issue. When these things occur it shakes confidence in the repair shop that is performing the work. It also shakes my wallet as I was not prepared for this expense at this time.
I am Not looking for fault at this time. I am looking for an answer to Why the issue occurred?