Probably a way simple thing, but I need help.

I recently replaced the glow plugs on my OM603, reamed out the holes, etc.

When I went to start it up again, there was no glow plug light and the car would not start. I checked the relay box and the 80 amp strip fuse was burnt in half. I got a new fuse today, put it in, cranked, no light, no start. I thought something might be wrong with the way I put the plugs in, but when I checked the relay again the new fuse was burnt in half too. Why is this happening? It is supposed to be an 80 amp fuse, correct?

I dont understand that much about electricity or wiring.

Also: Should you be able to start the engine with just compression on a hot day? Without glow plugs I mean. I couldnt, is this an indicator of poor compression?

Thanks for your responses!

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'87 300TDT 150k

Were they new glow plugs? Did you test them before you installed? Sounds like something is grounding out that is not supposed to be.

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Jim

They were plugs that I got from the guy I bought the car from. I guess they had been in another engine that got junked but they looked really good. Tips in really good shape and clean.

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'87 300TDT 150k

Well I doubt that it is your glo plugs that are causing a short. Here is what you could do - make an end cap out of a piece of plastic tubing or use duck tape to easily wrap the end terminal end of each glow plug wire. If your engine is 5 cylinder you will have five wires, 6 cylinder 6 wires. I think that on the W123 there is a wire from the glow plug controller to a temperature sender also. Is it possible that you have the temperature control wire going to a glow plug. Anyway, with all ends insulated with duck tape, install your glow plug wires one at a time. When or after it is installed, check to see if it works and make sure the fuse doesn't blow. Make sure the insulation stays around your wires until you install them. Will a car start without glow plugs on a hot day. Many will, but not all will start. On the 616 and 617 engines the valves have to be adjusted pretty right. I thought your later engine was an easier started engine, what with hydraulic lifters and such, but maybe I am wrong.

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Used glow plugs must be tested before installing.
I junk any that read higher than 0.7 OHM and/or fail to (bench test) glow correctly.

Here are all the pictures and technical material you need for testing.

http://www.peachparts.com/shopforum/2360231-post8.html

http://www.peachparts.com/shopforum/diesel-discussion/134359-never-touch-hot-diesel-glow-plugs.html#post986836

http://www.peachparts.com/shopforum/2611938-post13.html

How do Glow Plugs work? | Ask Pete

http://www.peachparts.com/shopforum/diesel-discussion/137732-glow-plugs-link-thread.html#post1019018

http://www.peachparts.com/shopforum/diesel-discussion/104547-glow-plug-testing.html

.

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I even bench test new ones prior to installation.

__________________
Jim

X2,
That way if they are faulty & need to be returned it is clear that they are new ~ never installed.

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That would blow the fuse though if one or more of the plugs was bad?

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'87 300TDT 150k

If the glow plugs are still installed, measure resistance to ground at the 6-pin connector into the relay. Each should be just less than 1-ohm. My guess is you'll find one grounded.

The glow plug terminal is insulated from the flats used to tighten the glow plug in place. If you bend the loop connector such that it touches the uninsulated section of the glow plug, you'll have a short circuit. A glow plug wire with poor insulation is also a candidate for a short circuit. Find the short circuit and fix it.

Sixto
87 300D

without a meter, the easy thing to do is, look at each glow plug connection. I bet you have one of the wires spun around touching the injector line or intake manifold. it's REALLY tight in there, you have to be careful with the wires.
you could also have overtightened one of them, and damaged it.

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Today I took the manifold back off and discovered that one of the glow plug wires near the nut was bent up to where it was touching the manifold. This is probably what was causing the fuse to blow out ever time. I also replaced the semi-used Bosch plugs with band new Monarks. Although I hear some people say they dont like the Monarks as much, that they go bad.

Well it fires right up now, glow plug light and all. And it has a little more get up and go since I turned the ALDA up 3/4 turn. Tomorrow I think i'll do another 1/4 turn.

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'87 300TDT 150k