Glow plug replacement questions


so regarding the 2007 with the 3.0l OM642. Is it also A problem?

glow plugs also being a potential problem too? Or is it limited to the previous sprinter with that particular glow plug design? Manufacturer?


Well-known member
Broad statement.
Less prone but you do get them occasionally seized in the head and cross threaded by a previous installer.
Being thinner you have to treat them very carefully or they will snap off at the hex head section.

Drilling them out is harder due to head casting designs and pockets.
I use a timesert to recover the threaded hole and set the new one in the head. Seems to work for me.

Remember on these engines the glow plug is used for re-gen (de-soot) activities so its an important and an integral part of the sub system and must be maintained to ensure proper de-sooting.


I understand. Thank you. so right now I have all six 6 glow plugs that are installed now in the engine 3.0L OM642 soaked in with nut bolt penetrant.

Being thinner you have to treat them very carefully or they will snap off at the hex head section.

ok then. please tell me how to treat them and what to feel and look for when gently beginning to remove each one? what is your past knowledge experience on this particular glow plug 3.0l om642 please. Thanks for the past reply too. Rob.
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Well-known member
From what I see it makes no difference if the head is hot or cold unlike the older 5 banger which seems to "like" being very hot before you crack them loose.

I usually approach them with a double depth 8mm six point socket, short extension and 12 inch pivot head Snap On ratchet. A slight nudge with the tool usually cracks them free and they will freely spin out.
If they have a tendency to bind, I spray the plug cavity with Pen' lube and work them gently back and forth increasing the rotation each time feeling for a yield point. Obviously a bit of mechanical sympathy is required to successfully remove the glow without sheering it off.

Of course I have recently sheered one off having been crossed threaded and the hex head "cocked" a few degrees to one side (easy done if you force it). What the mech' was doing when he installed it was anyone's guess and a quick thread chase and clear with compressed air would have most likely have made a successful install which was easy to subsequently remove it.
The comment I got from the previous installer was well I am not a diesel mechanic--lame excuse!
Just go easy and take your time if they are tight, even train a blow lamp on them if it will help the removal.
Best of luck


New member
I have a 2002 Freightliner Sprinter 2500 Engine.. And I just replaced the control module for my glow plugs.. But have found the plugs a bit puzzling to take out.. There seems to be little to no actual room to fit a wrench in that area to loosen the "cap" above the plugs.. A fuel line looks to be in the way.. How did you get your Glow Plugs out?
Many Thanks,


A Dad owner with a '03
Well I guess it's time to revisit this post. I have a modified relay with fuses that I put in years ago when I lost a glow plug and the relay. The glow plug light came on again the last time I drove her. I checked the 5 20 amp fuses, but none are blown. I think I will try the (5) 10amp fuse trick and see if I have one that's open. I have about 137, 000 miles on Mona these days. I wonder if I should go ahead and try to change them all? Scary!

ktm 300

I b ought an 04 2500 2yrs ago with 38k miles. Didn't know about the glow plug situation then. Anyone care to guess which is more pertinent, age or mileage? I've got 80k on it now. Would it be helpfull to idle the engine (after getting up to temp) without the fan belt to raise the hd temp up to say 220?


06 T1N Can
I would drive it around the block if you can to raise the temp. Idling will take a long time, unless you can activate the diesel heater.


Well-known member
In short yes, I have several of these kits!

Caveats;- It does work!-A strong yes but with qualifications!

The issue isn't the tool its the circumstances and the operator!

Much more difficult with the OM612 due to manifolding!

Available to space at the back of the head makes it more difficult to do the job!

So going back here, the tool will work quite well if the glow plug was a quality unit. In many cases a cheap glow plug was installed which eventually (swollen up in the head) and broke off upon removal attempts. The material body is often "soft" and though it will take a tap cut of 5 x 1,00mm (supplied in the kit) the extraction adapter fails when the puller mandrel is exerting the extraction force ripping out the threads.

The drilling guide mandrel is very good at centering itself in the head recess! In some cases however its too long which limits what size of hand drill you can use.
The results is that you go drilling it off centre taking out the head threads and "going oval"!
The other issue maybe more serious is that the glow plug is coming apart inside AND by you drilling into it the tip drops of and falls in the head. Don't laugh it has happened to me!:rolleyes: Then its a definite head off!

Hence I have made a dummie injector to blast the cylinder full with shop line pressure as a precaution!

In any case you may have to install a helicoils or a timesert (my preferred method ) to recover the threaded portion of the head once the old glow is out!

To sum up the tool is better suited for use with engine out of the vehicle. And I have dripped the engine in the frame to gain access to the back "glow"!

I sometime abandoned the the tool and use a simple angle air drill and cut the body out with an aircraft precision drill & home made guide being about 8" long--Jobber lengths won't do it for the most part!

Much of this work boils down to judgement calls!
An hour per glow maybe two tops should do it, especially if a customer is paying shop time to extract the glow.
On the 612 the manifold may have to come off --a 11 hour jobbie by itself!
In these cases a 15 hour job will cover the head off plus parts (cheap) and a spark erosion machine & head job exercise.
Its machining work basically something that is an integral part of motor vehicle construction but not taught these days in MV Tech schools sadly!

Now a word on what some have called a Sprinter Specialist and broke them.

I will often scratch my head on this side of the pond at American s reverence of thing German ALL HAIL CAESAR--:lol: KAISER !
This permeates all the way down to an American mechanic who changes his name to Stefan from plain old Steve! Then put a shingle out with "WERKS and "TEKNIC" somewhere in his handle and claims he is German. When really his third maternal great grandmother came over in an immigrant boat from Silesia! :lol:
On the other side of the pond this would proffer a chance for Brits to poke fun and take the pi$$ so beware! Like doing a John Cleese act from Farty Towers!:lol:

Look buyer beware here, and you might be better off and in more caring hands giving your Sprinter to two good ol' Buds machinists --biker dudes at Bubba's garage!:laughing:

Sorry to be a bit cynical in this area but I don't tolerate impersonators too well or Con-men for that matter!
Neither so I like people who call themselves Mechanics and Techs when they are not ualified be be so! A bit like saying you are a Doctor or a Dentist when you ain't! But merely a Physicians Assistant :thumbdown:
All the best
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Active member
That's why I run with no working glow plugs in my OM612 and use the aux htr for preheat in cold weather.
thanks , my engines are the 2004 and 2005,on the 2005 OM647 the first and the third glow plugs needs to be done. clever the dummie injector to pressure the cylinder !


New member
I wanted to post my success story on glow plug removal (thanks to this forum). 2006 158" High roof 2500, 90K miles. Got the dreaded "glow plug heater circuit malfunction" code X2 (engine light on). Following someones advice here, I shot WD-40 into the plug wells each morning for a week before driving. Today I started the motor, pulled the wires (so I could get to the plugs quicker upon returning- hemostats worked great for me) and took a 20 minute drive to get the engine up to temp (arrow at the "1" in "180"). Pulled into the driveway, jumped in there with a 10mm deep socket on a 1/4" ratchet and all 5 came right out with a nice little pop sound and minimal pressure, couple foot pounds probably. I know the WD-40 made a difference, as the threads and plug shafts were lightly coated with it upon removal. Relieved!


New member
Hi all - I need help identifying the MB numbering of the 6 glow plugs in my 2010. Below is the only diagram I could find. So I've added the labels in red, hoping that someone here can tell me which is which. I.E. A=1, B=2, or whatever the correct order ACTUALLY IS. Many thanks in advance!!



2008 3500 170"ext. 3.0 V6 OM642.993
Hi all - I need help identifying the MB numbering of the 6 glow plugs in my 2010. Below is the only diagram I could find. So I've added the labels in red, hoping that someone here can tell me which is which. I.E. A=1, B=2, or whatever the correct order ACTUALLY IS. Many thanks in advance!!
VanGuy As per your diagram: and the front of engine is at the top of pic.



Aqua Puttana

Poly - Thread Finder

By posting history here the OEM factory fitment was Bosch or Beru.



My OEM plugs were still good at 140,000 KMS with original module /relay but fearing they get stuck in there so i replaced them anyway with a new set of OEM ones + New improved module and again no problem till I started using "Bosch" brand name plugs and they wouldn't last past 30,000 !!! Bought me another set of OEMs that cost way more of course and will put them in come winter .I use a block heater with a mechanical ( 4hrs) timer too .

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