I tested my glow plugs by a live on the battery to a bulb and the touched the

[mercmancdi]

How accurate is this.
I used a wire from live on battery through a bulb and touched the top of the
Glow plug with the other end completing the circut , (ignition off) on the plug I know to be dud the bulb did not light but on the others the bulb lit ..is this a good indication the ones that lit the bulb are good....

 

[Simon21]

Yes, but I'd change all at once, so finding the duds is a bit academic.

 

[SilverSaloon]

just remove the glows and connect them stright to a battery to test if they are dead and how well they actually heat up.

you can remove the glowplug relay and use a multimeter to test each plug without removing the manifold or plugs

 

[Rory1980]

Glow Plugs

It sounds like an agricultural sort of continuity test... And i would not take it to be accurate,

I was always taught by my apprenticeship boss to remove each glow plug and watch what it does in 'real time' because resistance and power draw /continuity will only tell you half the story,

And true to that i have often see glow plugs that draw plenty yet never get Red, and some that get red half way up the plug.

You would need to take them out and be sure that the very tip glows red hot in a uniform amount of time for each one of them- seeing as the heater light goes out on the dash very quickly- id imagine they should heat up near instant.

As said in the other reply you would be better to change all 4 together and have the new ones correctly ordered from part numbers waiting before pulling the old ones,
I know in recent Bmw,s they were an absolute b**tard to get out of the head and often warranted head removal to extract them,

Hoping the Benz engine is not in the same boat on that but someone else who works on them everyday would be better qualified to give removal advice .

Good luck

 

[mercmancdi]

The problem is i took off inletmanifold etc to remove them but so much hype about them breaking ( one at back of engine broke already prob some yrs ago
although the other 5 look fresh compared to it) the car is not worth very much so dont want to remove head ..that is why i am scared to try to remove them.
Had a mech call and look this morning he said to clean out inlet manifold pipes etc and leave well alone as he tried them with one of those prongs with a clamp on battery and a clamp on the tip of the plugs he reckons 99% the other 5 are they lit his light.

 

[Rory1980]

Might have taken it up wrong but what was the initial problem they you expect to fix by putting it back together without anything being changed bar cleaning it...

 

[mercmancdi]

Bit of a cop out I know but the cars for our dogs and will be ok till I have more time or can afford to pay to get the broken plug removed. The car heater light works ok and she starts fine just a bit lumpy for the first minute or so.

But it's a good car for myself for a past time and have learnt a lot by working on it and with the help of forum members like yourself I thank you.

 

[Rory1980]

So there was one broken in it i didn't get that part.
The light goes on and off that quick they cant do that much anyway Imo

You could try your luck shocking it well with a punch and breaking it off near level with the head and drilling a hole and hitting a good quality Torx spline down into it... but i don't think they'd take bigger than a T30 in which case your only gettin so much pull on it, and if that doesn't work shes outa action.
And thats about as much as any engineering shop will be able to do anyway because it would be hard get any heat focused on it in place.

Sure 4 good ones is enough for any yoke - give it the redline as soon as she fires to clear the smoke out and keep her lit !!

 

[M80]

If I remember right these glow plugs are rated at 4.5 volts so don't want to be connected to 12 volts. Also if shorted within you will see the bulb light with your test so a resistance check with a multimeter would be preferable.

 

[mercmancdi]

just remove the glows and connect them stright to a battery to test if they are dead and how well they actually heat up.

you can remove the glowplug relay and use a multimeter to test each plug without removing the manifold or plugs

I have a multimeter i can use it to test volts , but can not get the hang of where to set it to do glow plugs if i put picture of multimeter on can you explain a little to me as to when the switch should be for glow plugs and what reading i should expect and how to test at the relay plug. ps should i be posting this in a new thread