grebes,

Does the GP light work now?

Keep the old GP in the glove compartment. You might need a spare sometime.

P E H

OK PEH, I'll bite.

What would he do with an old non-functioning glow plug?

Brian,

Put the old non functioning GP in an old non functioning engine.

Gbrebes said he had 2 old GP that were still good. I meant he should keep them for spares. I thought that was intuitively obvious.

P E H

funny around here the non Bosch plugs are twice the $ as as the Bosch plugs
i get mine for about 12$ that incluids tax

PEH,

I thought you had some mysterious way to resurrect a bad glow plug, LOL.

Reminds me of the ferry company that I used to work for. The owner would remove a water pump or an alternator or whatever and put it in the back room. After about three years or so, he would have somebody go back there and find one of these things which he then needed to use on one of the boats. So, we all dubbed that room the "recovery room". You put the old worn out parts in there and, voila, in three years they have recovered to the point that they are useable again

Brian,

Nope, when GP go open circuit, they are like a burned out light bulb, no ressurection.

Did the parts from the recovery room really work?

P E H

Nope. but we all got a good laugh out of it. In reality, the mechanic had to partially rebuild the broken component with various parts lying around in order to use it. He was not too happy.

I had this problem and my key cylinder was bad. If you jiggle the key cylinder and that seems to effect it, then that might be it. But replacing the key cylinder is a pain in the arse. Maybe you should ignor my reply.

After a few years with my 81SD and a few glow plug failures, I am of the belief that the glow plug light starts to act up after the third glow plug fails. Before that the only clue seems to be slow starts when either the engine is cold, or when it is cold period.
Can leave one stranded real quick out there.

I just went out and checked my GPs on a fairly warm motor and they were all under 1ohm. Sometimes I get a light, sometimes I don't, but for the last little while it has been starting worse everyday. Warm it always starts quick but cold it has been more so like I'm starting without GPs. Can the GPs still be bad and show up as good warm and connected? I think I'll take a look at the GP relay fuse tomorrow too, I have an extra one around anyway.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

I looked into this some more, I rechecked it with the glow plug relay harness unplugged and a cold motor to find the same values. However I'm quite certain the problem was that the nuts on the glow plugs weren't tight enough (some weren't even finger tight!). It started right up, no "weak cylinders" like it was doing before the light went out.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

BoostnBenz,

How did you measure the resistance of the GP? Did you measure them thru the GP cable connectors after removing the cable from the GP relay?

P E H

No I took one end and stuck it on the battery, took the other end and stuck it on the post of the glow plug. All were within .7 to 1.0 which I'd expect because last winter I had them out testing them. I thought I tightened them down but apparently they either vibrated loose or I didn't tighten them enough.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

Boost,

The way you did it isn't correct. You get parallel resistance readings that way. You have to remove the cable connector or all the GP are connected together inside the GP relay.

Going thru the connectors might have picked up the loose nuts on the GP also.

P E H

I did it right, I just didn't restate this in my previous post. Regardless it is better now, hopefully for a while. Thank god it did this in the middle of summer rather than winter! Thanks for the help PEH.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k