240d impossible start on the coldest day in winter.

So I just replaced my glow plug timer relay with the manual override and everything was working fine until today. I got out of bed to find that the temperature outside was -3f. I cycled the glow plugs for 30-40 seconds and tried to start the car to no avail, not even while holding the glow plug button and pushing the accelerator halfway down. I couldn't get it started and got a ride to school. When I got home at 3:30 I found the block heater and plugged it into an extention cord from my house. I let it do its thing for an hour and then tried to start it again with the same effect. I'm pretty sure the block heater is working because I opened the hood and could hear it making a humming sound. What could this be? Is it just the severe cold? Could my block heater not be working; I have a feeling it is the original from 1982. Thanks, Grey. oh, PS, I know the glow plug system is working because I can hear the relay click when I hold the button.

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Diesel Engine Specific Aid

Chassis Model Number

W123

Starting Issues 1982 240D

Tips on why your diesel won't start are included in my Diagnostic PDF guide. CLICK HERE to read more. If your engine is not healthy it just may not start when it gets that cold.

To see if your block heater is working what an hour or so and you should feel the block of your engine getting warm. Let us know what you find out.

Kent Bergsma

hm. When I had it plugged in

hm. When I had it plugged in I opened up the hood to see what I could see and did actually look for heat. The engine block felt cold to the touch though, as did (what I think is) the place where the heater attaches to the engine. Now if I'm not mistaken, the block heater looks like an extra-large glow plug connected to the engine block between the middle two glow plugs but slightly lower to the ground? Would the next step be replacing this heater(which I've heard is wuite a job) or would it be better to replace it with an after market heater?

Location of Factory Block Heater

The factory block heater is located on the passenger side of the engine below the intake and exhaust manifolds and just above the starter motor. It is almost impossible to see from the top. You have to get under the car to have access to it. Be sure that the cord is plugged in and that the electrical contacts are not corroded. It is true what you have heard. It is not easy to replace unless you have the car on a lift.

The factory block heater is a little more efficient than an aftermarket heater - Only you can decide which is best based on cost and effort needed to install.

Kent BergsmaÂ

Well considering I don't

Well considering I don't have a lift or very much money, I'll probably go with an aftermarket heater. But first I'll try sanding the contacts on the plug because they do look rather corroded. If I can get it started I'll put the car on some ramps and get under it to see what I can see. Just out of curiosity, what is that oversized glow plug looking thing between the middle two glow plugs anyway?