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

KylePavao · #1 01-12-2007, 04:14 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, 04:30 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, 04:42 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, 04:42 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......

yellit · #5 01-12-2007, 04:45 PM

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

KylePavao · #6 01-12-2007, 04:45 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 · #7 01-12-2007, 04:53 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 · #8 01-12-2007, 05:00 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 · #9 01-12-2007, 05:07 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.

KylePavao · #10 01-12-2007, 05:08 PM

Thats what I am thinking, but I dont want to burn up this 115 dollar investment...Ill check to parts car

KylePavao · #11 01-12-2007, 05:18 PM

Ha no voltage. Nothing. Zero zilch. Nada. This dieselgiant.com kit says it supports the W115....WTF...

Yup after doing all this BS the light doesn't even turn on. I read 12V with the power wire disconnected...but as soon as I go to the first jumpered plug nada.

kerry · #12 01-12-2007, 05:26 PM

Quote:

Originally Posted by KylePavao

Ha no voltage. Nothing. Zero zilch. Nada. This dieselgiant.com kit says it supports the W115....WTF...

Did you ground the temperature sensor some other way?

KylePavao · #13 01-12-2007, 05:30 PM

Right now its all set, and the temp sensor has only one wire connected to it.. its like its getting grounded someway else...this better work or Dieselgiant.com is going to have to take back this 115 dollar kit. I don't think I need a different relay or anything...

yellit · #14 01-12-2007, 11:42 PM

Sounds like your car has had something changed...This is easy to fix ....
Do not worry about the temp sensor....will come back to that later....
You need the head and block grounded good to the neg. Batt term. and frame and every other thing that looks like it has wires going to it...Extra grounds are great and solve a lot of problems.....transmission, alternator,frame....put in good solid grounds..........
Let us know where you are at with the project and we can get this going....

I have my own kit on my 1978 300D...works fantastic...I can shoot some pics if that will help.....It cranks so fast it is scary!....

TwitchKitty · #15 01-13-2007, 12:33 PM

You can make this work. Don't let it beat you. It is a worthwhile upgrade. Check the wiring diagram for the donor vehicle.