1976 W115 240D 3.0 glow plug type? - PeachParts Mercedes-Benz Forum

j-galap · #1 03-25-2023, 03:59 AM

Hi everyone,

I'm about to look at a 1976 W115 240D 3.0. It's got a glow plug problem so I wanted to order a set so I can do some tinkering.

I don't yet have access to the VIN or a confirmation on which type of glow plugs the car would likely require. Can anybody tell me what are the likely ones it'll be using?

A part number would be excellent too if that's possible.

Also, would this model have a glow plug relay?

The car was built in 1975 but registered in 1976 if that makes any difference - and is badged 240D 3.0 rather than 300D.

Thanks!

gmog220d · #2 03-25-2023, 06:41 AM

There is a glow plug relay in those cars. They do not have the gorilla knob for manual glow control like your '74 had.

As for the glow plugs, looks like it uses the older loop style.

https://www.pelicanparts.com/catalog/SuperCat/2363/MBZ_2363_ELIGNT_pg1.htm

j-galap · #3 03-25-2023, 07:09 AM

Ah, thanks Greg. Appreciate it!

What would it have instead of the gorilla knob then? I've never come up against a non-gorilla knob 240D in my experience up to now (which isn't too extensive, I admit!)

gmog220d · #4 03-25-2023, 07:19 AM

Quote:

Originally Posted by j-galap

What would it have instead of the gorilla knob then?

The relay controls the glow, like you find in later cars including W123s. You turn the key to "on", and watch for the glow indicator light in the instrument cluster to go out before starting.

gmog220d · #5 03-25-2023, 07:39 AM

I pulled my copy of Robert Nitske's book, "Mercerdes-Benz Diesel Automobiles", to see if he had anything to say about how these cars were badged for different markets. He tells the story that in the USA the new 300D, as it was badged here, was a step up in terms of "luxury features", while in other markets the options between the 240D and other W115 cars were more or less the same so they called them 240D 3.0. I guess, then, that these cars came out during the time M-B began marketing their cars in the USA as upscale luxury items rather than simply as cars with different options like they did in the rest of the world.

j-galap · #6 03-26-2023, 12:44 PM

Ah ha, interesting info for sure. This one is originally Spanish registered but it has been in the UK for a lot of its life - and locked away in a garage for much of that. From what I can see it's quite original other than 280 front bumper. Hopefully a diamond in the rough. Anyway, we shall find out soon enough!

gmog220d · #7 03-26-2023, 01:01 PM

Some of those cars had interesting paint colors. Be sure to show us a photo or two of the car you're going to look at.

Diesel911 · #8 03-26-2023, 03:29 PM

If you still have the old filament/loop type glow plugs if one plug burns out none of them work.

It requires you to change the glow plug wiring but the updated pencil type adapter glow plugs work better and when one plug dies the rest still work.

Somewhere in the repair links is threads that offer some instructions.

DIY Links by Parts Category - PeachParts Mercedes-Benz Forum

Sometimes the stock relay does not work with the adapter glow plugs and you also need to change the fuse to a higher amperage.

People generally make their own wire set. One of the main things you have to remember is that you will discard the ground wire that is at the very end front of the older glow plug set up. It may go direct to the cylinder head or go to a temperature sensor.

This could be one of the links to the conversion however the kits seem to be long gone: F1101-88322 KIT for converting LOOP series GP to hotter pencil parallel system

In the case of the adapter glow plugs Bosch or Monark plugs work. People have also used another company that I Connot spell right Heuco or something like that. If they are not the adapter type glow plugs don't use Monarks for later engines with the smaller glow plugs as they do not last.

j-galap · #9 03-27-2023, 03:07 PM

Quote:

Originally Posted by gmog220d

Some of those cars had interesting paint colors. Be sure to show us a photo or two of the car you're going to look at.

This one is exactly the same combo as my previous 240D (unfortunately, but I'll deal with it!). Ivory with a bamboo interior. From what I can tell, it's totally unrestored and is a bit of a survivor. Hopefully it is fitting to the description. Also electric windows, which would be a nice extra.

Will certainly post some pics!

j-galap · #10 03-27-2023, 03:08 PM

Quote:

Originally Posted by Diesel911

If you still have the old filament/loop type glow plugs if one plug burns out none of them work.

It requires you to change the glow plug wiring but the updated pencil type adapter glow plugs work better and when one plug dies the rest still work.

Somewhere in the repair links is threads that offer some instructions.

DIY Links by Parts Category - PeachParts Mercedes-Benz Forum

Sometimes the stock relay does not work with the adapter glow plugs and you also need to change the fuse to a higher amperage.

People generally make their own wire set. One of the main things you have to remember is that you will discard the ground wire that is at the very end front of the older glow plug set up. It may go direct to the cylinder head or go to a temperature sensor.

This could be one of the links to the conversion however the kits seem to be long gone: F1101-88322 KIT for converting LOOP series GP to hotter pencil parallel system

In the case of the adapter glow plugs Bosch or Monark plugs work. People have also used another company that I Connot spell right Heuco or something like that. If they are not the adapter type glow plugs don't use Monarks for later engines with the smaller glow plugs as they do not last.

Ah, that is some encyclopedic knowledge there - thank you for this. Will probably come in very handy if/when I buy this car