Glow Plug Weirdness

I have replaced all five glow plugs in my 1979 300D. After installing them and hooking everything up the way I thought it was when I took it apart, I attempted a start.
First of all, the glow plug light stayed on for at least a full minute, maybe longer--much longer than normal. When it finally went out, it FADED out, instead of just going out as normal. So when the engine failed to start, I glowed again and this time took a look under the hood, and the serial wires connecting the plugs were GLOWING RED! I have not seen this before, and assume that it is not normal.
I am at a disadvantage, because I do not have my MB Maintenance Manual CD with me, and am winging this job, with the help of people her, of course, but I believe I must have hooked something up wrong.
Any insights will be gratefully appreciated.
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First of all.... What type of glow plugs did you put in? The pencil type or loop type? I am betting you installed pencil type.... if so, you need to wire them differently.
With new glow plug style, you do not use those resistors that the factory put in. Instead you use just wires... Take a look at this picture on this page...
http://www.mercedessource.com/node/677
All you do is connect from one glow to another via that new wire.... so factory wire from last glow goes on as usual... then new wire goes from that glow to the next... and next to next.
There used to be a website with good picture tuitorial... but can't find it.
I think a 10 or 12 gauge wire is enough to make those connections... you can get them at Home Depot or Lowes... the loop crimp and bulk wire... look for high temp wire.
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I put back in the original "loop type" plugs. The looped wires that connect them are of various shapes. I carefully made sure that each connector went back on its proper glow plug pair, but may have gotten something wrong in the insulator-to-connector wire connections. I shall assume that the connector wires turning red hot is not normal.
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Doesn't sound normal at all... and why did you buy original loop type glow plugs when everyone offers pencil type kit for cheaper than the original plugs?
Did you ream the glow plug holes before youput new one in?
Take them all back out and reinstpect them again. The system is simple.
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You pose an excellent question. The simple answer is that I didn't look into upgrading to the newer pin-type plugs--a decision I now regret. I always tend to keep to original equipment and avoid modifications, so that is why I did not look into changing the system.
At any rate, I take the connectors all apart again, inspect the plugs, and re-install, hopefully the right way this time. I hope in the process that I am able to figure out where I erred in putting the connectors back in place.
Thanks again for the guidance and advice.
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snipped-for-privacy@mac.com ha scritto:

Uhm... pencil type... loop type... is there a difference, apart from pricing? How can I tell which glow plugs are installed on my engine without taking one out? And... what do you mean, Tiger, writing REAMING holes? I have two different meanings on my dictionary and they are pretty much different. One is 'enlarge the hole in the whole length', while the other is 'enlarge only at the entrance of the hole'. Tkx. Stefano
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On Nov 27, 11:44pm, Cordy

The best way I found to tell from the outside, aside from the existence of the connector rails, is that the hex head on the old loop type is 21mm. The hex on the pin type is much smaller, probably 17mm.
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On Nov 28, 2:44am, Cordy

Reaming is using either the MB reaming tool or an appropriate size drill bit and working it through the glow plug hole to remove carbon build up when inserting a new glow plug.
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