PeachParts Mercedes-Benz Forum - View Single Post - Buying a 1984 300CD that has been parked for over 20 years

BillGrissom · #2 05-29-2023, 06:34 PM

First thing I did after my first move from eastern U.S. to SoCal in 1991 was buy a 1965 Chrysler. Lived its life from San Luis Obispo to Edwards AFB. Not a spot of rust, even behind the rear bumpers. Like finding gold to someone from the east. You quickly learn to first touch water fountains with your knuckles in the Mojave Desert, even in Summer. Glasses of ice water don't even need a coaster. No need to have drained the diesel fuel, unless it sat right by ocean fog. It can sit 10 years in SoCal without getting enough moisture to grow black-slime. Otherwise, diesel doesn't evaporate appreciably like gasoline does. Only problem buying a car from an engineer is that it may have improvements, using say parts from the McMaster-Carr catalog (or Boeing stock?) that would likely confuse a gomer dealer mechanic, even if a smart fix or upgrade. Those guys will prove useless anyway, just stating, "can't get that part".

Diagnosing "no crank" should be easy. Step one is verify the engine isn't seized. You should be able to turn it over by hand. I use the hex nut on the power steering pulley atop the engine, using a long 22 mm box wrench. Might need to tighten the V-belt or at least push on its side to keep it from slipping on the pulley. Otherwise, fuss with socket extensions to get at the crank bolt with just enough room for a wrench to the radiator shroud (or pull it up, just 2 top clips). There is no starter relay that I know of, just direct from key switch to contactor on side of the starter via NSS and little screw terminal in front of the battery. You can jumper the contactor there. It is the smaller wire going to the starter, so just jumper to one of the other two screws (both are BATT+, one feeds the starter motor cable). Even with an auto transmission, your year can actually be push-started if you get it rolling up to ~35 mph and shift from N to 2nd (read manual). That is because is has a rear pump, as does my 1965 Dodge Dart automatic (dropped soon after).

If the engine then turns over but doesn't start, insure the glow plugs are getting power. You should hear the GP relay clunk off after 20 sec. On cold days, you can cycle it again w/ the key switch. The dash light going out just predicts "glowed long enough for a new engine", based on underhood temperature, but glowing longer never hurts and can be required for a worn engine to start. I once rigged 3 glow plugs to BATT+ w/ jumpers when I had the GP relay out for repairs and needed to move the car. It wouldn't start without some heated up, even on a 70 F day. If it still won't start, verify the lift pump inlet filter isn't clogged (clear, or just change it since cheap). Might need to crack the top tube nut on each injector to let any trapped air out as you crank, especially if someone ran the fuel tank dry to get air into the IP. Before that, pump the hand pump on the lift pump to flow air bubbles out of the IP inlet supply. Any air will be compressible to perhaps keep the injectors from popping open.