78 240d glow plug light won't turn on

[thephreaker]

and neither will the car. Turns over but won't start. I replaced the glow plugs but that hasn't seemed to help. I checked the voltage and getting 12.4 to each one. Does anyone have any other ideas?

[kerry]

78 originally had loop plugs. does it still have them? Did you check the fuse on the firewall?

[thephreaker]

Originally Posted by kerry

78 originally had loop plugs. does it still have them? Did you check the fuse on the firewall?

Yeah i checked the fuse, appeared fine, was also getting 12.4v there. When i was replacing the plugs it had pencil plugs, but i replaced with bosch looped 80003 plugs.

[kerry]

What wires did you use? Loops require the heavy bent squiggly wires with insulators between the wires on each plug. If your pencil plugs were wired parallel, it explains why your loop plugs aren't working. Can you post a picture of the way you have them wired?

[Stevo]

Originally Posted by thephreaker

Yeah i checked the fuse, appeared fine, was also getting 12.4v there. When i was replacing the plugs it had pencil plugs, but i replaced with bosch looped 80003 plugs.

The newer style pencil type GPs are way better for faster starts and use less power, why would you go back to the loopers?

[kerry]

I'm guessing he went back to loopers because the retrofit pencil plugs with the large threads are harder to find. Not a step I would recommend.

[cooljjay]

Not that hard to find az still has them, no idea why you would go back....but this is for sure the issue.....Bosch pencil upgrade part number 80035....its stamped in my head...

[Skippy]

If you put 12 V to a loop plug, doesn't that blow it like instantly?

[thephreaker]

Originally Posted by kerry

What wires did you use? Loops require the heavy bent squiggly wires with insulators between the wires on each plug. If your pencil plugs were wired parallel, it explains why your loop plugs aren't working. Can you post a picture of the way you have them wired?

I used what was being used with the pencil plugs. Before I got these I didn't even know about pencil plugs and got them because thats what a catalog suggested.

see images

[Left Coast]

Well, that ain't gonna work.

The loop plugs, which were original to that year, are wired in series using special resistance wires between the plugs. As installed, you have no connection to ground, so the plugs won't glow. The easiest solution for you is to find some pencil style glow plugs that will fit. There have been periods in the last year or so when availability wasn't very good, but I think you can find the Bosch plugs at several vendors now. Unless you completely revert to the series wiring system, which is inferior, you have no choice but to locate some new pencil style plugs.

[Skippy]

I've had a '77 with loop plugs and an '83 with pencil plugs. Trust me, you want pencil plugs.

[cooljjay]

We all make mistakes, its a good thing you have a place to ask questions!

I would reinstall your old ones, and then return these and get the right ones....I can't post a link to where I got mine as they are on another site....

Here is a reference photo of the wires we are all talking about and spacers...

[Stevo]

Mystery solved

[thephreaker]

I will try new Bosch 80035 pencil plugs and report back. Appreciate the suggestions all

[thephreaker]

Got the pencil plugs a few days ago and the car started up fine. Drove today to the gas station, put some gas in, now the plug light doesn't glow again. Car is stuck at the gas station