HI all from Missouri! 240d start problem
 

I am looking at a 240d that won't start............I am a farmer and have been around diesel engines.......but not mercedes.........I need some direction........

figure I will start with glow plugs and relay...........where is relay located?

battery is low from them trying to start it.........I will jump it with big cables I use on Farm tractors........where is starter plan on tapping on it........

Anyone that can take a moment and give me some insite I would sure appreciate it..........as this is my first maybe Mercedes............

it is I believe either a 78 or 77 model

any help appreciated!
Thanks Scott

Going to look at it like 1030 Monday morning........

Relay is on the drivers side fender. Black box with a couple cables going into the top. Most likely you have dead glow plugs. You'll need to replace them or its not going to want to start if its below 65-70F out. Starter is on the passenger side of the engine below the air cleaner housing....don't crank too long or it will fry the starter, fix the glow plugs first. You could also have a fuel issue, clogged filters or tank strainer, or air in the lines etc....

well from what I was told it started one day.........next day it wouldn't I figure glow plugs are bad too.........can you shoot a little either to these( I know just a bit not much) to start them in emergency?

Scott

I don't think the relay is in that location on this car. 77 or 78's, if original, have series glowplugs. If one goes out, they all go out. If original, the plugs get their power from a box on the firewall, juice goes thru all the plugs to the ground at the first plug at the front of the engine. You can tell if they are working because the heavy wires that join the plugs will glow red hot and be visible if the sun is not too bright.
Inside the little plastic box on the firewall from which the plugs get their juices is an 80 amp strip fuse. They can get hairline cracks and fail. You can use a small heavy gauge jumper wire between the screws that hold the fuse to get juice and test the plugs. You could also use a jumper wire from the hot terminal on the battery directly to the first plug at the back of the engine.

If plugs are bad, you really want to convert it from a series loop system to a parallel pencil system. Conversions plugs are available. Search the forum for the part number. The conversion plugs are not the same as the later pencil plugs because the threads are larger. To convert, remove the series plugs, remove the ground wire from plug at front of engine. Use wire from the firewall to energize the first plug at the back of the engine and put jumper wires between the remaining plugs. This will improve cold starts immensely.

Only use ether in an extreme emergency with the glowplugs disconnected.

If you can farm, you can fix it.

Don't use ether. Some suggest wd-40. Where in Missouri are you located?

Kevin
1978 300D
1979 240D

The glow plug relay on the early models is under the foot well panels. It is a silver box, and it's it located right near the steering column. It sounds like bad glow plugs to me if it started one day and not the next.

Little shot of ether shouldn't hurt anything.

If you're nervous about the glow plugs igniting the ether - just turn the switch on and then let the car sit for a full minute before you try to start it.

Then, you are 100% positive the glow plugs have stopped running (If, as we do not suspect, they are working) - after that point, give it a quick, short, and one-time-only shot of ether to see if it'll start. If it does, we know your fuel delivery and things are probably okay.

After that, fix it right :D

Ether doesn't kill these cars. Irresponsible use of ether kills these cars.

most older tractors use the same type glow plugs, so you should be familliar with them.
if not, bear in mind that they are series IF they still have the large bendy metal bracket looking wires between each glow plug. simple check is to put volt meter on engine block and last glow plug and check for any voltage. if you have around 3 volts, you are good. if you have 0 you are bad. the fuse on the firewall on that old a car is 50A, not 80A... have fun!