1985 Mercedes 300 SD. Car was sitting for a week and its been in the 30s at night. I go to start it and nothing. Find out it keeps blowing the flat ( strip fuse? ).

I checked the ohms and find out the number 3 plug was open? is that what it's called? it was the only one not reading 01

Checked and sure enough it was almost off of the nut. Tightened it and now same exact thing, instantly snaps that strip fuse.

I checked carefully and don't see any wires touching frame, etc. everything looks good.

Now what? Is that box with the wiring harnesses shot?

Car won't even "pop' or attempt to fire. Just turns over.

Read my recent thread...you have a short somewhere. In my case, it was a wire that was part of the entire glowplug harness that had had its insulation rubbed off. Check each plug wire for a short to ground.


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1987 300TD
1984 300D
755,000 KM and going strong
BC Canada

If the short is not in the wires to ground it is inside of the relay itself.

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84 300D, 82 Volvo 244Gl Diesel

EFFFF. Ok, thank's guys. I'll take a closer and longer look at things. Gotta get this car moved out of the driveway soon before snow.

One more quick question related, if I use Ether to start it will the car continue to run just so I can get it into the barn?

Ether is not recommended, you can stretch head bolts and do all kinds of damage, many use WD-40 instead. However, if you use a starting fluid, be sure that the glowplugs are NOT powered (be sure the fuse is blown), and use it very gently, ... you can give it a light squirt and try, a little larger squirt if that doesn't work, etc. so that you err on the lean side.

And yes, once it starts it should continue to run, ... rough until it warms up a bit.

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Gone to the dark side

- Jeff

There is a good chance once the Engine runs it will remain running. However, before trying to crank and start it is a good idea to get on the Hand Primer and make sure the Fuel Injection Pump Housing is full of Fuel and no air; that will increase the chance of fuel being there to continue to run the Engine.
When you have pumped all of the Air out you should hear a buzzing or faint squeaking noise coming from the Fuel Pressure Relief/Over Flow Valve on the Fuel Injection Pump.

There is other alternatives to Ether like spraying in WD-40 and other stuff.

However, if you insist on using Ether disconnect the Glow Plug wires where they plug into the Relay (in this case you don't want the Plugs to igniting the Either too soon) have someone start cranking before you spray and you spray only as much as needed.
That is they way my Boss did it where I used to work.

It prevents you from spraying a whole bunch into the Air Filter Housing and then have a big slug of Ether suddenly entering the Engine (which is likely to happen if you spray a bunch in and then run to turn the Key and crank) and prevents you from using more then you need.

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84 300D, 82 Volvo 244Gl Diesel

Did you remove the wire from each glow plug before you checked the resistance? If not, you've not really tested each plug, only the whole wiring harness. You said the #3 plug was open and not reading 01, did you mean 0.00? Zero ohms? If so, that's your short right there.

If that's the case, you can disconnect that plug, insulate the connector, and start it on 4 GP's. It'll be smokey and rough until that 5th cylinder lights, but will let you move the car.

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617 swapped Toyota Pickup, 22-24 MPG, 50k miles on swap

Fwiw, I plugged my block heater in for an hour or two and then it started right up with no glow plugs.


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__________________
1987 300TD
1984 300D
755,000 KM and going strong
BC Canada