Hmmmm..........in addition to the resistance check of the glow plugs, please perform one more task:

Remove the cap to the fuel tank and attempt to start it again.

.......stranger things have happened........

I think once you have checked out the glow plugs, fuel would be the next order then valve adjustment check.
In previous posts, you mentioned:
Changing out the secondary fuel filter. Are you talking about the spin-on or the in-line filter? What did the in-line filter look like? Was it black in color?

Also, have you done any adjusting on the rack dampener screw? This is a screw with locknut adjustment on the back, firewall, side of the IP. If it has been adjusted too far in, it may cause hard starting.

You also mentioned a couple of emergency adding of canola oil. How long ago, how much, and what were the temps?

Then with the valve check, I believe the clearances should be 0.10 mm/intake and 0.35 mm/exhaust. (This is a problem that caused hard starting on mine. The exhaust and intake valves had been adjusted to the same 0.10 mm)

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Sam

84 300SD 350K+ miles ( Blue Belle )

Sorry if this has already been clarified, but does the oil pressure gauge peg when the key is turned on and before the engine starts? If so, the wire to the sender is grounded.

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1982 300SD

I changed the spin-on filter. The "clear" plastic in-line filter appears to have dark fuel in it, not sure if its black since the translucency of the plastic isn't so great. The canola oil burned in total was maybe around 10 gallons. I was in the middle of nowhere Kansas, and the only dino-fuels I could find nearby were 87 and 89 octane. The last time canola was in was in September, probably not below 70 degrees. I haven't messed with the IP at all.

I'm gonna "borrow" a multimeter from the University and check resistances on the GPs.

I tried starting with the fuel cap off...no go.

The mechanic did a very good job fixing issues with my SL, he admits that he hasn't worked on diesel engines in almost 20 years though. So far he's been completely honest, which is more than I can say for all but three shops in this city.

Other items of note: I was slightly mistaken with the oil pressure gauge. It pegs at 3 bar even while the ignition is at 2 and the engine is not running. This started immediately after getting the car back from the shop that broke a bunch of stuff and then charged me $120. Also, when the car stopped starting, the power locks stopped working. Today they are working. Don't know whats going on there.

Sorry I can't update on more, its difficult for me to do work on the car since automotive maintenance is explicitly forbidden in my apartment lease...I have to be careful.

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73 450SL AMG "Millennium Falcon"
88 Volvo 740GLE B230F/M47
84 300SD Turbo (Sold, looking for new one)
86 300E (FOR SALE)
78 450SL (totalled by girl on drugs in SUV)
87 Volvo 740GLE wagon (totalled by Ford Expedition)

try using an amp meter thats what I do and it works great. I can power each glow plug individually and measure it's current. I think they start out using about 25 amps and within a couple of seconds when the filiment heats up they drop to about 5 amps. I can check the the amp readings for sure if you would like.

What's the specification for the amperage? Is it 5 amps.......or 6 amps......or 7 amps after 5 seconds?

What's acceptable........what's not?

You don't know.........because there is no specification for this.

After months of frustration, my 300SD gave up. With everything seeming normal, the car still just wouldn't start. The local old MB shop checked it out and made a very expensive prognosis. The engine would not start without a two person process involving the injection pump. The compression on one cylinder was about 300, and on the other four it was between 210 and 250. The valve lash was checked, and only two valves were too tight, and one of them was on the cylinder with good compression. There was a lot of blowby, you could see gases puffing out the broken crankcase vent hose. Injectors 1-4 looked fine, but injector 5 looked bone dry and had a white powder on the nozzle. The coolant system was pressurizing before the engine was running, leading them to believe that either the head gasket had failed or the head was cracked near that injector. I was surprised since I never saw any coolant loss and never smelled any coolant burning. Staring at repair bills that could now escalate to $5,000 (new head + labor + previous work) I cut my losses and sold the shop the car but still had to pay them $250 in labor since they had done more in work than the car was worth. If I would have kept the car I would have ended up financing the towing company owners next Jamaican vacation.

Thank you guys for all your help. Its time to go shopping for another I guess...

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73 450SL AMG "Millennium Falcon"
88 Volvo 740GLE B230F/M47
84 300SD Turbo (Sold, looking for new one)
86 300E (FOR SALE)
78 450SL (totalled by girl on drugs in SUV)
87 Volvo 740GLE wagon (totalled by Ford Expedition)