Almost done replacing loop plugs...ground question - PeachParts Mercedes-Benz Forum

KylePavao · #1 01-12-2007, 05:14 PM

Alright the pencil style retrofits are in, however the W115 chassis the temperature sensor for the glow plug relay has two wires: one that connects to the plugs themselves, and another that seemingly leads to the relay. The issue is there is no ground strap on the engine. Is the ground built into the large metal piece here?

EG:

On the left, the piece with the black wire attached to it has two wires coming from it: one to plug number one, and the other to I assume to relay. With these new retofitted plugs I need to eliminate the ground, so is this it?

Regards,
Kyle

kerry · #2 01-12-2007, 05:30 PM

The ground I had to eliminate when converting plugs was the one that went from the front most plug to the block. I think I see that wire in the left part of your picture, going from the plug to the block. There was no other wire that I can recall. I just then hooked the rear most plug to the hot wire and jumper wires to the remaining plugs. Has worked fine for a few years.

KylePavao · #3 01-12-2007, 05:42 PM

I mean on my vehicle I see NO ground strap at all, only a second black wire from the left hand "temp relay thing" that goes to plug number one. A possible ground?

yellit · #4 01-12-2007, 05:42 PM

Picture is too dark to see the ground connection.....Just make sure your new plugs only have one wire from each one to your relay or switch....The head is grounded by being attached to the block....The old style plugs had the last or first plug by cylinder # attached to ground and then to the next plug up the string with the buss bars.....Parallel new style plugs use the housing of the plug as the 2nd conductor which is ground when they are screwed into the head.....The new plugs are all fed 12 volts from the relay or switch depending on how you wired it....I think this is what you are asking......

KylePavao · #5 01-12-2007, 05:45 PM

Like I said it seems I have no ground strap...I have no idea how my old plugs were grounded in this W115 chassis if I didn't have a ground strap..

This isn't a pic of my engine, but I will get one as soon as camera battery is charged up

kerry · #6 01-12-2007, 05:53 PM

The ground strap is right there in the picture. The last plug has a braided wire that goes from the plug to the block and is held down with an allen head bolt, behind and to the left of the dipstick right on the head. Way left in the picture.

KylePavao · #7 01-12-2007, 06:00 PM

This is as an example. I am trying to tell you that my vehicle doesn't have a ground strap like this, but instead has another black connection from the larger area to the right of where the ground strap is in this example picture, and this second black connection attaches to glow plug number one.

So what I am trying to figure out is where the glow plugs are grounded in my particular system.

The picture is NOT my car, simply trying to tell you how my system is different from the one in picture.

I appreciate the help guys.

kerry · #8 01-12-2007, 06:07 PM

Oh. It sound as if your system is wired in series with the temperature sensor. I would guess that is the ground and it needs to be removed. There needs to be one hot wire going to the first plug, a jumper wire going to each one and no more wires attached to them.

yellit · #9 01-12-2007, 05:45 PM

Can you get better pics..?..A flashlight or anything to brighten it up some...