Hello everyone,
I'm a mechanical engineer from New York, recently moved to California. I've been enamored with Mercedes cars for as long as I can remember, and have many pleasant memories of riding around on the rear bench of my father's 350SL, and of learning to drive in the mighty 560SEL. A few weeks ago I bought my first project car, naturally choosing a 6.9 as a good starting place for the beginner
. The details (and photos) in the listing were pretty sketchy, but from what I have seen on the car and the documentation that came with it, this was an early Euro spec model imported through Houston in 1986 as a grey market car. It was driven by an electrical engineer here in the SF bay area until 2002 when the seller bought it from a scrap yard. He failed to get it running, and after purchasing a new engine and transmission (??), he..... let it sit, for 18 years, until I bought it. I haven't registered it with the DMV yet (and am now far removed from the ten day window in which I was supposed to, oops) so I cannot get the data card from the classic center yet, but I am very interested in obtaining it. The title lists the model year as 1900, the import documentation lists 1976 and 1977, and the data plate near the radiator bears the leading digit "5." If it is a 1975 model, having proof will come in handy as the car would otherwise need to pass smog in California, which means I would need to restore the aftermarket closed-loop lambda control system retrofitted by the importer, to working condition.
The car is in pretty rough shape overall. The interior is totally dried out and crackles painfully when disturbed, the paint is sunblasted and there is some rust over the driver's door where a vinyl top once trapped rainwater, and there is forklift damage to the side skirts, floor pans, and trunk pan, but I believe the car was originally totalled by a failure in the fuel distributor. My thinking is based on the following facts:
1.) The airflow meter plate moves freely and does not feel like it is touching the control plunger at all.
2.) The car came with the fuel tank in the back seat, having been replaced by a red jerry can in the trunk.
3.) Removal of the valve covers brought forth the hideous stench of old gas.
4.) The engine, I was told by the seller, would turn over with the starter but not stay running.
Based on this I was pretty sure previous owner had flooded it while trying to fix something fuel related, and my attention turned to determining whether it had any bent rods, having recently finished a reading of Raueda1's horror story of an experience with a maladjusted fuel distributor last summer. What I have done so far is this:
0.) Bought missing 6.9 emblem on ebay as a good luck charm.
1.) Borescope inspection of cylinders via spark plug hole revealed the pistons were generally dirty and looked as though the engine had been running very rich, although some had VERY clean areas where fuel had pooled, dissolved these deposits, and evaporated.
2.) I sprayed PB blaster into the cylinders, and blew them out with compressed air to be sure there was no solid debris lurking
3.) I turned the engine over with a breaker bar and 50mm socket at the crank pulley, for two laps of the timing chain and found no problems
4.) I tuned the engine over with a new battery, and measured compression. The workshop manual says to do this with a warm engine but that's not really an option for me. Overall, readings looked good. In Bar and in order 1-8 they measured 10.5, 11.5, 10, 11.5, 11.5, 9.5, 10, 10. Cylinder 6 is a bit low, but the gauge I used was rented from O'Reilly's and was coming unscrewed all the time. Minimum spec is 8.5 Bar, and all cylinders should be within 1.5 Bar of each other. The camshafts are mostly clean, and the oiler tubes are at least dribbling oil onto each lobe (I replaced the oil, but did not bleed air out as the manual suggests, as the engine does not run yet). I feel good enough about this result to proceed, which brings me to today.
What do I do now, w116.org? I am planning to remove the retrofitted lambda control system until I can get the car running. I've ordered a rebuild kit for the FD as well as the WUR, and plan to get these components working on the bench before shelling out for new injectors and trying to start the engine for real. There is a lot to do, and I've already written a wall of text in this post. I plan to update this thread as I make progress over the next few months or years. I look forward to writing back and forth to you all, and to learn as much as I can about these cars, as we appreciate an excellent series of top-class autobahn cruisers together!
- Nuggies
