W124 300D Changing Glowplugs - How easy/ Tool

d215yq

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Hi all, I have a week in February where I won't need the car so in addition to upgrade headlights/oil/filter air filter change I would like to change some of the glowplugs if possible. Car always starts (even at -5) so I don't want to take apart inlet manifold etc but according to the internet there are 4 of 6 that can be changed without removing anything so I'd like to just change those - might make the starts smoother as currently it judders/splutters into life with a bit of white smoke when ambient temperature less than 10 degrees, doing 2 or 3 ignition cycles helps reduce smoke/start better so assume glowplugs are not all good.

Has anyone done this without removing the manifold and is there any specific tool that can be recommended. Is it possible they could break when removed so best left alone or with penetrating fluid will they be OK? Not sure when they were removed although head was reskimmed and valve seals done 2 years ago so would they have removed them then so they should be OK or would they have just left them in while doing all that?

While I'm at it main fuel filter is 3 years/60k miles old, does that need replacing too?

Appreciate the advice here as always, Ben
 

alexanderfoti

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My advice would be to leave them well alone if they are all functioning correctly.

If you snap one you will be left without a functioning glow plug in its place.

It is possible you have one down with behaviour like that. I have attempted to change one set on a 300 TD W210 and had 2 break in the head. That was with undoing them, and spraying penetrating fluid over the course of a week. I did manage to drill them out in situ but it was a major pain.
 
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LostKiwi

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Agree with Alex.
The fuel filter should be changed.
 
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d215yq

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The thing is two years ago glowplug light went out and it didn't start great so I assume one went. This year worse so another one has gone. So if I just leave it and another one goes when will it not start..and will they not get harder to remove with age? The glowplugs get power because if I try to start it instantly it just turns over and doesn't start until a few seconds in, whereas if I wait 10 seconds it always fires up straight away, allbeit rough.

Can these engines start without glowplugs or with just 1 or 2? What's the critical number where it could leave me stranded? Apart from an occasional ski trip it stays above 10 degrees here March to December so it's not a huge problem as it is...

Atleast will change the fuel filter. New air filter/fuel filter might help it start a bit better anyway.
 

alexanderfoti

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Its possible you have a few out.

They will not start without glow plugs unless its really hot outside (25 Deg c+) and you will still struggle.

Its true, the longer you leave them, the harder they will be to remove, but do you know how long they have been in there for?
 
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d215yq

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Its possible you have a few out.

They will not start without glow plugs unless its really hot outside (25 Deg c+) and you will still struggle.

Its true, the longer you leave them, the harder they will be to remove, but do you know how long they have been in there for?

Thanks, they'll have been in there between 30 and 3 years, unless they were removed when head was skimmed/valve seals done. Car came with no history whatsoever. Still I don't think I'll touch them if they are this tricky, I don't have the skills to be drilling things out and will only have a week of down time before I need the car ready and working for some long journeys. I'll put some penetrating fluid around them just in case they need to come out some time.
 

om613

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It's nearly impossible to snap the fat f****ers used in an OM603!:)
they're Not thin like 605/6 and cdi GPs.

I think I did them with manifold on?? (7 years ago), and prob a 12 mm deep socket?
yes fuel filter is due too. (50K)
 

alexanderfoti

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It's nearly impossible to snap the fat f****ers used in an OM603!:)
they're Not thin like 605/6 and cdi GPs.

I think I did them with manifold on?? (7 years ago), and prob a 12 mm deep socket?
yes fuel filter is due too. (50K)

Aha!! yes, you remind me now, mine where on a om606. The ones on the 603 are much like my Kubota.
 

brianbrian

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I have changed many glow plugs on those engines, no problem, just make sure engine is warm, you will have to take air filter box of.
 

Doug1234

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I changed all six on my w124 a few years ago , as mentioned air filter off and you can reach them all by using a few cable ties to hold throttle linkage out of the way.
 


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