Glow plug replacement

[mercman149]

Evening,
In the next few days intend to check the resistance of all 6 of the glow plugs on my ML as the warning light stays on for several minutes after the engine has started.
I understand you can check them without removing, but obviously faulty ones will have to come out.
How easy is access for removing them and do I need to remove anything more than the turbo air intake pipes on the top of the engine.
Any advice and tips greatly appreciated.
Thanks.

 

[onefortheroad]

Om642 pretty straight forward . The 2 close to bulkhead can be tricky to remove the electrical plug, use a 1/4 inch drive socket n ratchet .

 

[mercman149]

Thanks for the advice. I managed to remove and check 5 of them but the one nearside one nearest the bulkhead was broken when I got to it. Has anyone ever removed a broken glow plug with the cylinderhead still on the engine? I'm not even sure if there is enough clearance to do so with the removal kits I've seen for sale/being used on You Tube.

 

[EmilysDad]

.... Has anyone ever removed a broken glow plug with the cylinderhead still on the engine? I'm not even sure if there is enough clearance to do so with the removal kits I've seen for sale/being used on You Tube.

I paid some one else to do mine after I broke it. It was organised by a local indie & I was charged £100 which I thought reasonable

 

[onefortheroad]

Have you had the ml long then ?

 

[mercman149]

Have you had the ml long then ?

Yes, had it for 5 years. First time investigating the Glow Plugs. The five I removed all appear to have correct resistance.
Next task is a new or reconditioned turbo as the one fitted is blowing a bit of oil back down air filter pipe.

 

[onefortheroad]

Yes, had it for 5 years. First time investigating the Glow Plugs. The five I removed all appear to have correct resistance.
Next task is a new or reconditioned turbo as the one fitted is blowing a bit of oil back down air filter pipe.

Has the light been on for 5 years then. How do you think the glow plug was broken ?

 

[ajlsl600]

My guess.someone been at it before and when another seemingly ok plug started to fail light started to stay on longer.
I alway found plenty penetrating oil around hole on.a fairly hot engine ,left to cool and a single flat long depth socket on a long bar would do job.
Prob comes when one cant get access or has to use inadequate tooling.or some git at benz decides that tooling of last 30 yr no longer good enough and redesigns to some unnecessary tooling .

 

[Blobcat]

Prob comes when one cant get access or has to use inadequate tooling.or some git at benz decides that tooling of last 30 yr no longer good enough and redesigns to some unnecessary tooling .

Or the "Engineer" that designed it hates mechanics...

 

[ajlsl600]

Wtfitf!!!

 

[Stagman]

I paid some one else to do mine after I broke it. It was organised by a local indie & I was charged £100 which I thought reasonable

Are you able to provide more details please? I am worried about mine on an E300 as the last time I went to my local indie for all 6 glowplugs to be replaced, they only did the one failed one, as they didn't want to risk a breakage. Another has now gone.

 

[M80]

I try to tighten a tad before removal, to break the 'seal'.
But as said, hot engine, if it don't want to come don't force it -better to spray penetrating fluid and spray and heat for a week.
But a bit late for you.

Ah, I remember the old more bulky glow plug that could take torque. New one's break if you look too hard at 'em. Especially the ones at the back that might be difficult to get at with the perfect angle on the socket.

 

[V6Matty]

Agreed, though even with one already failed you can still soak all the plug holes and get things really hot before attempting to take them out, you should be fine but just take your time

 

[EmilysDad]

Are you able to provide more details please? I am worried about mine on an E300 as the last time I went to my local indie for all 6 glowplugs to be replaced, they only did the one failed one, as they didn't want to risk a breakage. Another has now gone.

More details of which bit? I'd replaced a single glow plug a while before along with the relay (local indie had said no5 plug was goosed so I replaced the single plug but it turned out to be the relay) so when the light came on again I bought the 6 again. 4 came out easily, I snapped one and waved a white flag for the 6th. Took the car to an indie who organised for the sheared plug to be sorted & to do the 6th. Perhaps I should've got the engine back to temp before I attempted to do plugs 4, 5 & 6

 

[V6Matty]

More details of which bit? I'd replaced a single glow plug a while before along with the relay (local indie had said no5 plug was goosed so I replaced the single plug but it turned out to be the relay) so when the light came on again I bought the 6 again. 4 came out easily, I snapped one and waved a white flag for the 6th. Took the car to an indie who organised for the sheared plug to be sorted & to do the 6th. Perhaps I should've got the engine back to temp before I attempted to do plugs 4, 5 & 6

When I did mine on the 270, I cracked them all off quickly before going back and starting to remove them so as to not let things cool down too much

 

[EmilysDad]

When I did mine on the 270, I cracked them all off quickly before going back and starting to remove them so as to not let things cool down too much

I'll remember that if I ever have any more to replace

 

[onefortheroad]

I'll remember that if I ever have any more to replace

Your meant to have a cuppa n bacon sarnie after getting all 6 out , not after each plug.

 

[mercman149]

Has the light been on for 5 years then. How do you think the glow plug was broken ?

Hi, the light only stayed on for 10 or so seconds after starting the engine and starting has never been a problem(until now) so didn't feel it was worth getting a garage to remove it. Over enthusiastic wrench monkey I'd guess.

 

[V6Matty]

Glowplus aren’t there just for starting they are in constant use for emissions