Newbie here, with my first questions for my first benz:

'73 MB 220D was always hard 2 start when cold since I bought her last year, but ran okay once she warmed up. Replaced older 'loop-style' glow plugs - #4 was broken off (inside engine, but I think I got all the pieces out!) causing cascade plug failure when wired in series - w/newer 'pencil-shaped' ones. Rewired in parallel so they glow independently of each other per: http://www.dieselgiant.com/mercedesdieselloopglowplugrepair.htm.

Didn't change fuse or relay 'cuz I can't find it.

New plugs getting power according to 12v test light. Traced wire from #4 (purple w/white stripe) thru firewall, still unable to locate any fuse OR relay either under the hood or dash. Where are they, how are they marked and how do I test them? All fuses in car look okay, and none have that color wire leading to them.

Also replaced all rubber fuel lines, old fuel and injectors (my shop tested them for free, old ones too worn), then bled the air out, but now she won't start. While replacing injectors, I did a compression test (twice) and she has >300 psi/21 bar on all four cylinders. Clear vacuum lines had oil inside them, so after a good cleaning, replacing the vacuum pump diaphragm and checking for adequate vacuum, I suspect it's my fuel injection pump diaphragm, right?

Pulled the rear section off the IP and the diaphragm doesn't appear torn, just shows a little leakage near the bottom. Must I remove the IP from the engine to change it? If yes, how do I keep the IP drive gear locked so it doesn't move? And if I must go to all this trouble, should I have my shop (Southwest Diesel in Phoenix, AZ) bench test it for wear & tear? I fear they'll want to charge me both arms and a leg to repair it, whether it needs it or not! Like I said b4, car ran fine once she warmed up, and never leaked fuel.

I'vw set crankshaft timing to 24*, but b4 I remove the last pump bolt, please tell me where the timing marks are on the IP & cam pulley (both #1 cylinder lobes up?) so I don't screw up timing? Thanks!
p.s. – done this procedure a few times on my VW diezels, but this is my 1st benz, appreciate any advice.

Welcome to the forum. You're going to learn the "search" feature will be your new best friend.

In the future, I'd think about "fixing" one thing at a time and making sure the fix is OK before moving on. Near as I can tell you went from a hard cold start to a no start with unkown glow plugs, air leak, injectors, timing, and governor installation.

First thing I'd do is a search for "runaway engine." This is what you may get if you don't hook up the governor diaphragm assembly correctly (to the end of the injection pump rack).

Then I'd find the service manual. Lots of good stuff in there.

Then I'd put the timing back to where it was and make sure the new injectors have new "washers" (and the old ones are really out). Not sure why you did this as you said the engine ran fine when warmed up - ahem, cough cough.

If you have the cannister secondary fuel filter with the filter-to-injection pump line from the bottom of the cannister then you basically have a gravity fed injection pump. May have put a big air bubble into the injection pump when changing fuel lines. Make sure the injection pump overflow is a clear line, then hand pump and watch for bubbles coming out of the injection pump. I'm assuming your hand pump is OK - that's another source of air. Make sure the return-to-tank line is working - that's where the bubbles are supposed to go. There is a vent screw on the injection pump, depending on the model of pump.

Then make sure you've installed the new parallel glow plug system correctly. The old series system, if you have the gorilla knob and salt shaker, isn't fused and doesn't have a relay. Search for gorilla knob and salt shaker if you don't know what they are. Wiring diagram from the service or owner's manual also helps here, or use an ohm-meter with one long jumper (disconnect the battery first) connected to the disconnected purple wire at the first engine glow plug (rear engine cylinder). Think of the salt shaker as the first "real" glow plug. I don't know if you need to bypass the salt shaker when converting to the parallel system - I like the series system with the salt shaker telling me how the system is working. I'd be very carefull about leaving glow-plug bits in the pre-chamber, by the way.

Then make sure all your battery cable ends are clean-bright-tight, including the ground strap near the starter. Now we're at the first step in diagnosing a hard cold start....

Good luck, and keep us informed.

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daBenz - 1970 220D

I am not sure if I read correctly.
Did you update to the Pencile type Glow Plugs that are wireded in parallel or did you wire your old Loop styple Glow Plugs in parallel?

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84 300D, 82 Volvo 244Gl Diesel

My manul only goes back as far as 1977.
What it shows is the Loop style Glow Plugs with a wire going to a Glow Plug Resistance something Control.
This is that round metal salt shaker top looking thing that on the Dash that Glows when you apply the Glow Plugs long enough.

From there the wire goes to the (also called the Push-Pull Switch) Mechanical-electrical Preglow-Start-Stop Switch (I saw no Fuse in the drawing of the circuit).
So since the switch is mechanical there is no Relay and there may be no fuse at all.

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

Before you move or remove the IP put 2 marks in line with each other; one on the Engine and 1 on the Fuel Injection Pump Flange. This way you can always return the IP to the origional position.
I use a Tungstun Carbide Scribe but I have also seen people use a Chisel or put a Center Punch Mark on each side aligned with each other.

I have A Volvo Diesel and the Enbine is made by VW; it also has a similar Fuel Injectin Pump. The timing method is different.
Go to the upper right of this page and look for the "Resources". Put you pointer over that but do not click. look at the menue and click on DIY Links. This will take you to the Do It Yoursel Links and look around until you find The Drip Timing Method.

Other than to do Drip Timing would not mess with the Fuel Injection Pump except as a last resort.
Also in our Forum we have a Vintage Mercedes section.

Added:
The Working the Hand Primer alot bleeds air from the Low Pressure/FuelSupply section of the IP. Do this first.

However if you run out of Fuel, changed the Spin On Filter (full of air) without Pumping on the Hand Primer or for some reason remove the Fuel Injector Hard Lines (as when removing the Injectors) you will need to bleed the air out of the High Pressure Section of the IP.

You do this by leaving all of the Injector Hard Line Nuts up by the Injectors loose (threaded on but loose) and cranking the Engine until you see Fuel comming out from under all of the Nuts. Then you tighten them and attempt to start.

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84 300D, 82 Volvo 244Gl Diesel