I did a lot of searches, but im still learning and had a few questions.....

First, if the relay clicks on and then clicks (I would assume off) 30 seconds later does that mean it works?

I dont have a multitester... I wanted to go out and buy one, but the car doesnt start easily. Is there any other way to test the plugs? I see the appropriate wires connecting to inserts. Do i just undo the nut on these inserts to pull out the plugs?

Also I noticed on fast lane that relays are somewhat expensive, yet the kit with the four plugs and the relay is less expensive...What up with that?

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1983 300SD White with Grey interior

Probably...
Mmm, soon have one you will
Well, you can remove them and connect 12v to see if they glow. DO NOT TOUCH THEM FOR A WHILE!
Not sure what you mean. The glow plugs are like miniature spark plugs. Undo the nut that holds the wire onto the cap (HOLD ON TO THE NUT, IT WILL TRY TO ESCAPE) and unscrew the glow plug.

So I got a multitester and tested the plugs. The first two read 3 ohms (could they still work like this). The third didnt read anything. The fourth and fifth had very high resistance (like 50 ohms or something like that). I am assuming that all are bad and will be replacing them. Is there anything from these readings you can interpret apart from that.

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1983 300SD White with Grey interior

The glow plugs are resisters, just like a light bulb. The more resistance you get the better they will work.
50 ohms good
3 ohms bad
infinite totally not working.



Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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I thought they were supposed to measure between.8 and 1.2 ohms?

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1983 300SD White with Grey interior

Yep, a good glow plug will measure right around 0.6 ohms.

Len

They do have a resistance element, like a light bulb, but...
Not quite true!

Let's review the formula for power P, with voltage V and resistance R

P=V*V/R

So, the higher the resistance, the less power you get. In the case of M-B glow plugs, the cold resistance should measure 0.8 ohms or so.

With 12V applied, each glow plug draws 12*12/0.8 = 180 watts. It's like a high-power light bulb in each pre-combustion chamber, and things will warm up nicely.

As others have said. 0.6 to 0.8 ohms is GOOD.

If your glow plug was 50 ohms you would have a 12*12/50 = 2.9 watts, or about half the power of a a nite-lite. Not much warming is going to happen with that

Alright...So I ordered the Glow Plug Kit on Fastlane and one extra glow plug....Anyone have experience with this "Kit." Does anything have to be changed on my current system because in Fastlane it mentions that the relay provided is different and allows "the plugs to function for up to 3 minutes." Whats this all about? Good or Bad? and why is this kit cheaper than buying a relay by itself?

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1983 300SD White with Grey interior