220 CDI glow plug change

[David Pemberton]

Part 1 of 2

Tools, parts & consumables needed:


(Click for larger image)

Multi-meter (not shown)
Torx 30 bit and driver
Pliers
Torque wrench
10 mm deep socket
Extension bar for socket
4 x glow plugs (Mercedes part A001 159 49 01)
Penetrant spray (3-in1 Professional from Halfords)
Elephant bog roll

Time to do the job: 1 hour (I spread this over a week, see below as to why this makes the job easier)

Expertise: moderate (about the same as changing spark plugs or changing engine oil)

Car on which plugs changed: C220 CDI, 2000 W-plate / 202 193

[NB the use of left and right relate the car as viewed from the driver’s seat looking forward.]

The first symptom that something is wrong with your glow plugs may be that the glow plug warning light comes back on immediately after the engine has started, and remains on for up to three minutes before going out for the rest of the journey. The reason that the light comes back on (after going out to indicate that pre-heat has finished) is that the glow plugs continue to work for up to three minutes after the engine has started to improve cold running. The system detects that there is a problem during this after-heat phase and lights the warning lamp.

The diagnosis method is to test the electrical attributes of the glow plug system (it is an electrical problem that has tripped the warning light) and to do this you’ll need a multi-meter that can measure resistance (ohms).

Open the bonnet to its fully upright service position by releasing the hinge locks (left side first) and raising it to the vertical, position whereupon the hinge locks will re-catch to hold it securely (to return it to its normal position release the left side first, the right side doesn’t need releasing on the way down). Remove the engine cover by unscrewing four Torx screws using a Torx 30 bit. You may also need to remove the oil filler cap to make it easier to slide the cover off. Remember to replace the oil filler cap immediately so that debris can’t enter the engine.

The glow plugs are located on the upper left side of the engine (see picture).


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Each plug has a push-on black electrical connector cap.


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Remove the cap by gripping it with pliers and gently but firmly pulling upwards. Test each plug with the multi-meter set to measure resistance. Touch one of the multi-meter probes to the engine (for a good earth) and the other to the silver tip of the glow plug. The three working glow plugs on my car gave a reading of 0.6 ohms, the defective glow plug read zero. If all the plugs have a similar reading (and I’ve seen elsewhere the acceptable range being 0.5 to 1.5 ohms) then the plugs are probably OK and this DIY isn’t for you. You could continue your investigation by checking the operating voltage for each plug of 11.5v, and, if your meter can manage it, the current draw of ~15 amps. That way you can see if there is a break in the individual feed to a plug and perhaps trace the problem back to the glow plug control unit.

Continued in Part 2

 

[David Pemberton]

220 CDI glow plug change Part 2

Part 2 of 2

But this article is about changing glow plugs, so assuming you have diagnosed a faulty plug, here’s what to do next.

I read a lot of posts on this forum that made me very wary of taking the plugs out myself: tales of sheared and broken plugs, reaming out threads, and blowing debris out of cylinders by running the engine didn’t make me feel comfortable. But I did read a very good post about taking plenty of time to let penetrating oil do its work. So I decided that this would be the route for me, and I allowed myself a week from diagnosing the problem to fixing it, during which time I applied 3-in-1 professional penetrant spray to soak in overnight every night. Once you’ve taken the engine cover off for the diagnosis, you can leave it off for the rest of the week and still use the car; applying the spray just takes a minute each evening.

After a week of applying penetrating oil I gave a final spray, and drove the car briefly to get the engine up to a cool operating temperature (~60C). To remove the glow plugs, unclip the cap that supplies the power to the plug (as described in the diagnosis section above), and use a 10 mm deep-reach socket fixed to an extension and torque wrench. I set my torque wrench to 20 Nm which is what the Haynes manual says is the tightening torque (albeit for the glow plugs in the older 2.2 and 2.5 diesel engines). My logic being that I’d be very unlucky if they sheared at this low setting, and if I couldn’t get them to unscrew I could review my options. After a week of penetrant spray each glow plug came out very easily, the torque needed didn’t seem near to 20 Nm. The plugs needed the wrench all the way and never got to the point where I could spin them out with my fingers. Once the threads were clear I pulled them out using pliers.


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This is what the plugs look like when removed. The new one is at the top of the picture - and no, I couldn't see much difference either...


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I changed all four plugs because I reasoned that at 80,000 miles if one had failed the others would be near the end of their life too. I used Mercedes original parts because after half-an-hour search online for glow plugs I wasn’t much the wiser as to which Bosch plugs were right and who would sell them to me, e.g. the Eurocarparts website simply doesn’t list anything for my last-of-the-202s but CDI powered car. The Mercedes items are made by Beru and cost £13.77 + VAT each. My franchised dealer is friendly and helpful, recognises that I’m never going to pay his service rates on a car worth about only £6k, and probably hopes (rightly) that one day I might buy a second hand car from him. So I buy most of my parts from him and enjoy a look around his gleaming showrooms at the same time – how the other half live!

The glow plugs screw back in to 20 Nm torque (again they need to be gently driven all the way, always needing more torque than my fingers would provide), then re-fit the push on caps that supply the power. A quick check round the engine bay to make sure no tools have been left lying about, then start the car as normal. On the first start the glow plug light came back on again after the engine had fired, so I cursed a bit and doubted my diagnosis. On subsequent starts the light has behaved normally, i.e. going out to indicate the end of pre-heat, and staying out when the engine has fired. I can only assume that during first run of the engine after the plug change, the glow plug circuitry was still running a fault mode that didn’t clear until one complete correctly functioning start & run cycle had been completed.

After a test run the only thing left to do is replace the engine cover. Before you do this it’s worth having a wipe round with rag, especially by the oil filler if past spills have occurred. The oil filler cap needs to come off so that the cover can be slid back into place, make sure that you mate the engine cover and the silver manifold cover by sliding the lugs together (see picture). A final check round for discarded tools and the job is done.


(Click for larger image)

 

[Parrot of Doom]

An excellent DIY thread, worth moving to the DIY section I'd say.

Was there any carbon buildup on the shafts that the glowplugs screw into?

 

[Blobcat]

An excellent DIY thread, worth moving to the DIY section I'd say.

It may already be there...

 

[television]

It may already be there...

He is a kind man at heart

 

[mattkh]

Hi

What a lovely writeup.
Just 2 questions.

1. Where does all the penetrating oil end up ?

2. What is the point of using a toqrue wrench set to 20 Nm when you are unscrewing the glow plug ?

 

[David Pemberton]

Hello

1. Most of the penetrating oil evaporates if you continue to use the car during the week as I did (a very light oil so not much residue left). The bit that you apply on the day you remove the plugs ends up in the cylinders - didn't seem to cause a problem on starting.

2. Using a torque wrench set to 20 Nm when you remove the plugs prevents you from applying too much unscrewing force thereby shearing the plugs (I read elsewhere on the forum that this can be a problem). If you can't budge them at 20 Nm you have a few options:
a) get braver and up the torque a bit
b) use something like a freeze releasing spary (e.g. from Halfords)
c) give up and take it to a specialist who if they shear the plugs have the right kit to ream out the threads

Best wishes

David

 

[W203-C220]

My thanks to Mr Pemberton for this excellent 'GLOW PLUG REPLACEMENT' guide that has given me the courage to examine my own cars glow plug problem. You mostly see horror stories about things shearing off and massive bills!
On mine, plugs 3 & 4 are both open circuit but as they are all originals at 90K+ I guess thats not a bad life span? Not tried to remove any yet but got a set of 4 OEM Beru parts (BB GN003) ordered from GSF for just under £7 each + vat. These seem to be the very same spec and type the dealer offered me for £13.77 + vat by the way!

I checked it all out on the Beru website. http://www.beru.com/english/produkte/produktfinder.php
A very useful place to start if, like me, you were looking to buy the 'best quality' parts at the best price.
Worthy of note was the mention that ALL Beru glow plugs are finished in a bright nickel-plating which prevents corrosion and must NOT have copperslip etc applied to them. But on a different page they quote a GKF grease specifically for glow plug refitting..... Installation Information: Cover glow plug thread and -shaft with mounting grease, (GKF 01 - Order No. 0 890 300 034), before fitting to enable easier removal and prevent corrosion.

Presumably a legacy product from when they were NOT nickel-plated?
I have seen Wellman glow plugs on eBay for about the same money with P&P but reckon if Mercedes factory-fit Beru and stock them as spares too, they must be longlasting and the ones to go for.

The offical tightening torque they quote is 15 nm and they will shear at 35 nm so the use of a torque wrench REMOVING seems very sensible to me!

 

[W203-C220]

Job done with no problems for £32.67 all in

I bought 4 of the original spec BERU glow plugs from GSF at £6.95 each + VAT. The factory originals were exactly the same parts (GN003) with a MB logo and extra part number etched on them. I now have 2 working spares that have done 6 years+ 91K but still work perfectly well.

My own reasearch confirms GN003 pre AND post-heat glow plugs are for ALL the 4 & 5 cylinder CDI engines that's 200/220/270 models - even the late model 202 if it has the CDI badge like Mr Pemberton's.
They do NOT fit the V6 engine (C320 etc) NOR the earlier 220D.

With a hot engine I found all to be easily loosened and removed without the need for penetrating oil but maybe I was lucky?
The only thing worth mentioning is you really MUST have the right tools for this simple job. I bought a 'deep' 10 mmm socket especially and used my 1/4 drive racthet & long extention bar. Those long nosed pliers are essential too!
I found I had to undo and relocate something to gain proper access to cylinder 1 (or 2) but that was no great hardship.
Mine started normally at light off, no more light coming back on for 40 seconds which confirms all is now well I guess.
All my old working) plugs and the new set all measured 1.2 ohms by the way, using the cheapest nastiest Digital Meter you can imagine (about £5 worth) The failed pair were open circuit, that made it obvious which had failed.

A week before this I changed my Mass Airflow Meter (sensor only) which was a Pierburg and also the factory original. I paid £71 at a stealer for mine but these are under £46 + vat from Euro Car Parts in fact. Same part minus the MB logo & extra part number again. Minus the MB price hike too of course

 

[kebo57]

Hi
Iv'e read this thread & unless I'm mistaken there is no referance to lubricating the glow plug before replacing it.
Kevin

 

[W203-C220]

"Worthy of note was the mention that ALL Beru glow plugs are finished in a bright nickel-plating which prevents corrosion and must NOT have copperslip etc applied to them. But on a different page they quote a GKF grease specifically for glow plug refitting..... Installation Information: Cover glow plug thread and -shaft with mounting grease, (GKF 01 - Order No. 0 890 300 034), before fitting to enable easier removal and prevent corrosion. "

Presumably a legacy product from when they were NOT nickel-plated?

This was pasted directly from the Beru site - the part for my model in fact...
http://www.beru.com/english/produkt...+220+CDI+(203.206)&ktypnr=15722&action=step04

They clearly tell you to use GK1 grease, but in another helpful section they say never use any grease as they are all nickel-plated!
There was no prior mention of using grease in this post but I've seen other references to using copperslip elsewhere so I thought it best to mention it - that's all

 

[kebo57]

"Worthy of note was the mention that ALL Beru glow plugs are finished in a bright nickel-plating which prevents corrosion and must NOT have copperslip etc applied to them.

Yes I agree with "prevents corrosion" but won't impede the build up of carbon which would be the problem when you come to remove then again.
Any way when I did nine they had some white grease on them and I was glad that they did have:-|
Kevin

 

[Staffs ML270 CDI]

My thanks to Mr Pemberton for this excellent 'GLOW PLUG REPLACEMENT' guide that has given me the courage to examine my own cars glow plug problem. You mostly see horror stories about things shearing off and massive bills!
On mine, plugs 3 & 4 are both open circuit but as they are all originals at 90K+ I guess thats not a bad life span? Not tried to remove any yet but got a set of 4 OEM Beru parts (BB GN003) ordered from GSF for just under £7 each + vat. These seem to be the very same spec and type the dealer offered me for £13.77 + vat by the way!

I checked it all out on the Beru website. http://www.beru.com/english/produkte/produktfinder.php
A very useful place to start if, like me, you were looking to buy the 'best quality' parts at the best price.
Worthy of note was the mention that ALL Beru glow plugs are finished in a bright nickel-plating which prevents corrosion and must NOT have copperslip etc applied to them. But on a different page they quote a GKF grease specifically for glow plug refitting..... Installation Information: Cover glow plug thread and -shaft with mounting grease, (GKF 01 - Order No. 0 890 300 034), before fitting to enable easier removal and prevent corrosion.

Presumably a legacy product from when they were NOT nickel-plated?
I have seen Wellman glow plugs on eBay for about the same money with P&P but reckon if Mercedes factory-fit Beru and stock them as spares too, they must be longlasting and the ones to go for.

The offical tightening torque they quote is 15 nm and they will shear at 35 nm so the use of a torque wrench REMOVING seems very sensible to me!

Do you have a contact to buy these glow plugs in the UK???

Regards

Darren

 

[W203-C220]

ML270 CDI uses same plugs as mine.

Your ML270 CDI (Dec 1999 - June 2005) will use the same glowplugs I used in my C220 CDI.
GN003 pre & post heat enabled. Readily available @£6.95 +VAT from German Swedish & French (GSF) and many other automotive parts stockists I'd imagine?. Euro car parts will most likely sell these too.

Useful links: -

For your ML http://www.beru.com/english/produkt...+270+CDI+(163.113)&ktypnr=13163&action=step04


For your Mondeo - but check carefully http://www.beru.com/english/produkt...(B4Y)&typ=2.0+TDCi&ktypnr=16453&action=step04

In general http://www.beru.com/english/produkte/gluehkerzen/diagnosehilfe.php

Hope this is useful?

 

[Staffs ML270 CDI]

Brilliant a really appreciate your help.


Darren

 

[watsone91]

glow plugs

Bought a set of NGK glow plugs for my C250 they lasted 12 months then one of them failed , as this is quite a big job to do i will not be replacing with NGK it will be mercedes genuine parts .
This is an expesive lesson learned

 

[palmbay]

Really useful thread, many thanks.
You can also get the GN003 glow plugs and many others via Ebay seller yamaxor1. Presently listed under number 290187166450 for 24.99 plus 2.50 postage which isn't too bad. This number may vanish in time but hopefully if you do a search for the seller you shouldn't have any problems. (Unless he vanishes also!)
I, like others had dreaded this job, not so now, I will start the penetrating oil process tonight!

 

[W203-C220]

Might save time to try this first?

:idea:
Hi, with the benefit of hindsight I can say that as long as you don't suffer prior glowplug issues you will almost certainly be able to simply loosen and remove all glow plugs with a hot engine (never try this cold!) and should any seem 'stuck' try the penetrating oil thing on those only.
The plugs tighten into a taper seat (look at the new plugs) so unless loosened beforehand, oil cannot physically get into the threaded area where it'll help you anyway.
The most nerve-racking part for me was getting the new plugs threaded squarely back in ready to tighten. Because they will seem quite tight and squeaky coming out anyway you must ensure you don't cross-thread going back in. I took 5 minutes to replace 3 then an hour the 4th for this reason. All went well and I kept the 2 working originals for spares just in case.

Your eBay items are indeed the very same Beru parts I bought from GSF and a good price too. They only differ in price from the originals and lack the MB markings of course. Why pay more?

Fingers crossed for you anyway, remember to firmly press all the wire caps back on the new glowplugs, I'd do a cold start next day BEFORE screwing the engine covers back on too.

Cheers

 

[exeng]

glow plug taper seat

The taper seat on glow plug is just above heating element on bottom of glow plug and it is normally the element that swells causing plug to sieze in the head not the threads at the top of plug so i agree with warm engine before removal.:roll:

 

[malcolm E53 AMG]

Just to add re putting the glow plugs back I was recommended to use injector repacement grease (available from MB). A bit costly but should be better than putting them back dry and no doubt provide a good seal.

Just found part no for grease: A001989425110