75 diesel won't start - PeachParts Mercedes-Benz Forum

dlightf8 · #1 02-05-2008, 05:50 PM

When it got cold here a couple of weeks ago my 75 240D would not start. It did turn over, but would not quite fire, or it did actually fire a couple of times and ran for 2 seconds. I tried several times over a few days after the weather warmed up. I had to recharge the battery a couple of times. Now after last battery recharge I get nothing... no sound, no turning over at all. The starter had previously been sounding "funny" ever so often with a "zing" or two, before working. Any opinions on this scenario... do i have just a bad starter / solenoid or I wonder if I now might have two problems which may include glow plugs or relay or fuel filter or ??? Also I can't locate GP relay fuse.

kerry · #2 02-05-2008, 05:54 PM

First thing I'd do is check the battery, then the glow plugs. Don't know where the fuse is on a 75 but it's probably a series plug system and one bad plug causes the whole glow system to fail. Trace back the wire from the first plug near the firewall to a junction box and I'll bet you find a fuse there.

dlightf8 · #3 02-05-2008, 06:18 PM

Terminals look ok, which I know can be deceiving, I checked voltage at solenoid...12v. I still looking for the GP relay. Interesting... if one bad GP will cause it not to fire. My diesel VW vanagon will still fire with one or two bad GP so I assumed the same for Benz.

W123x3 · #4 02-05-2008, 07:02 PM

If the wavy heavy wire connectors between the plugs are not getting hot, the glow plugs are not working. They usually smoke or smell a little. I am thinking the glow plug relay may be under the dash. Don't remember seeing one in engine compartment.

dlightf8 · #5 02-05-2008, 08:28 PM

I'll keep you posted... tomorrow's another day... I will look for GP relay under the dash... thanks for the responses... Im surprised no one has mentioned the starter, more thoughts wellcome.

Palangi · #6 02-05-2008, 09:34 PM

Quote:

Originally Posted by dlightf8

I still looking for the GP relay.

You're gonna be looking for that relay for a long time, 'cuz there ain't one on a 75 240D.

Give us a step by step description of how you start that engine.

nate300d · #7 02-05-2008, 09:48 PM

What is the oil weight? I have been punishing myself using 15W40 this winter. She (my 1981 300D) sets outside, but she is always plugged in when it gets below 25F and starts like a champ even at 4F.

dlightf8 · #8 02-05-2008, 11:52 PM

Ok... I have started it like this for months...clutch in, or neutral... key turned to second on position... starter knob pulled to glow (resist) position... wait for glow indicater light to glow red... pullout to start. Anyway, even if I have a bad "in series glow plug" and "no glow plug relay on a 75" shouldn't the starter turn over? I think maybe it was on the way out and all this trying to start finished it off???

Palangi · #9 02-06-2008, 12:08 AM

OK, your starting procedure is correct. (You know the secret handshake).

I would start by checking the battery, sounds like it may be flat. Other possibilities would be the starter or the pull switch. Some years may have had a seat belt relay, but it sounds like yours was bypassed or maybe never had one.