Glow plug or glow plug relay fault W209 270cdi

[PhilippeM]

I wonder if someone could help me please? I have a 2005 CLK 270 CDI with about 150,000km on the clock. Have just started getting the glow plug warning light coming on after engine starts and then extinguishing after about a minute. A read up on different forums suggests it's either a failed glow plug or a failed glow plug relay.

I've just tried to get an OBD reading using my iCarsoft MB11 reader but I'm getting no DTC faults found. I've read on other forums that one should get a fault code indicating which glow plug. Since I'm not getting this could it be the relay or should I also get a fault code for this? Am I maybe misusing the diagnostic tool?

Cheers

Philip

 

[Wighty]

When my warning light behaved the same , the fault was a single glow plug . I did at a later date replace the glow plug relay anyway when the car was taking longer to start .

 

[umblecumbuz]

The 270cdi engine will start without glowplug assistance in any but the most severe weather, so - as Wighty says - it's probably a single glowplug at fault but it shouldn't stop you using the car normally until you can get it fixed.

You can check the operation of individual glowplugs without using a scanner if you're reasonably adept.

 

[PhilippeM]

Thanks for the replies. Changing the glow plugs I would rather avoid if possible, but if one is at fault I will change all five. I've read up on the job and it seems important items are: 1) lots of freeing fluid like Plusgas 2) engine hot and 3) Use a torque wrench to undo and do not exceed a certain setting or glow plug can shear!

Before I go any further it really would be great if someone with experience could answer following questions:

Does anyone have the setting for the torque meter?
Does no-one have experience with this particular engine and the iCarsoft II OBD reader?
Does a faulty glow plug relay also give the same warning light and should it give a fault code as I am not getting a faulty glow plug fault code?

Cheers

Philip

 

[Wighty]

Thanks for the replies. Changing the glow plugs I would rather avoid if possible, but if one is at fault I will change all five. I've read up on the job and it seems important items are: 1) lots of freeing fluid like Plusgas 2) engine hot and 3) Use a torque wrench to undo and do not exceed a certain setting or glow plug can shear!

Before I go any further it really would be great if someone with experience could answer following questions:

Does anyone have the setting for the torque meter?
Does no-one have experience with this particular engine and the iCarsoft II OBD reader?
Does a faulty glow plug relay also give the same warning light and should it give a fault code as I am not getting a faulty glow plug fault code?

Cheers

Philip

If you look at YouTube you can test the glow plugs whilst they are in the car using a cheap electrical multimeter , by doing a resistance test . It’s easy , I managed it as a first timer , and the test clearly identified a faulty glow plug .
At that time I just changed the one plug and that fixed my problems .
I would do this test first , multi meter might cost £10-15 .
Changing one faulty glow plug will then confirm if the relay is working or not

 

[Rory]

I just had one of mine changed. Indie wanted to change them all - I've no problem with that as I'm sure once one goes the others will follow - but I said to him to replace the one that had failed (it was no1) and see how easily it comes out. He called and said it was really tight, so he left the others alone.

 

[Larkone]

Was there not an upgraded/improved glow plug relay from MB, might be worth looking at that as well.

 

[Wighty]

Was there not an upgraded/improved glow plug relay from MB, might be worth looking at that as well.

There is for our om642 , not sure about the op’s

 

[umblecumbuz]

No need even for a multimeter.
A length of wire with both ends bared is all you need to check a glowplug.

Remove the connection (or busbar in some cars) from the glowplug that you're testing.
Hold one end of the wire on the battery live terminal.
Briefly brush the top of the glowlug with the other. If you get a spark, the glow plug is working.
If no spark, the glowplug is duff and needs changing.

 

[Wighty]

No need even for a multimeter.
A length of wire with both ends bared is all you need to check a glowplug.

Remove the connection (or busbar in some cars) from the glowplug that you're testing.
Hold one end of the wire on the battery live terminal.
Briefly brush the top of the glowlug with the other. If you get a spark, the glow plug is working.
If no spark, the glowplug is duff and needs changing.

Do you have to be careful with some cars with that method if like mine the glow plugs are 4.4v , not 12v

 

[umblecumbuz]

Do you have to be careful with some cars with that method if like mine the glow plugs are 4.4v , not 12v

'... briefly ...'!
Glowplugs are very tough animals and take a lot of stick with no ill effects. Done this a few times with no downside yet.

 

[PhilippeM]

Thanks for the additional advice. As I have a multimeter I’ll test in first instance using this. Presume with one lead on top of glow plug and other end earthed i should get a very low resistance reading. If all are the same then they’re ok?
Cheers, Philip

 

[PhilippeM]

Ignore my previous post as I’m being a numpty! Would someone please advise correct test with multimeter or guess I can find it on the internet?
Cheers, Philip

 

[EmilysDad]

..... If all are the same then they’re ok?
Cheers, Philip

.... or all goosed

 

[Wighty]

Ignore my previous post as I’m being a numpty! Would someone please advise correct test with multimeter or guess I can find it on the internet?
Cheers, Philip

I got my info from YouTube , one of the readings was different to the others , can’t remember what exactly they were

 

[EmilysDad]

I got my info from YouTube , one of the readings was different to the others , can’t remember what exactly they were

I compared the resistance of the plugs in the car with the new one I'd already bought

 

[W245207]

Thanks for the replies. Changing the glow plugs I would rather avoid if possible, but if one is at fault I will change all five. I've read up on the job and it seems important items are: 1) lots of freeing fluid like Plusgas 2) engine hot and 3) Use a torque wrench to undo and do not exceed a certain setting or glow plug can shear!

Before I go any further it really would be great if someone with experience could answer following questions:

Does anyone have the setting for the torque meter?
Does no-one have experience with this particular engine and the iCarsoft II OBD reader?
Does a faulty glow plug relay also give the same warning light and should it give a fault code as I am not getting a faulty glow plug fault code?

Cheers

Philip

Engine: 646

Releasing torque 25Nm max.
Tightening torque 19Nm.

Note, some torque wrenches only work one way, limit tightening torque but not releasing.

 

[Doug1234]

Here is a link that shows how to run tests using a multi meter to do all checks needed
http://dieselgiant.com/glowplugrepair.htm

 

[umblecumbuz]

Here is a link that shows how to run tests using a multi meter to do all checks needed
http://dieselgiant.com/glowplugrepair.htm

Worth bearing in mind that this write-up is for an earlier relay box that has an easy pop-off top, and is also for 12 volt glowplugs.
Your engine has a different arrangement, although the basic test principles are the same.

 

[PhilippeM]

Thanks for the further replies. I'll check each glow plug tomorrow with my multimeter using info above and basically checking if one is very different.

On the torque values W245207 you say engine 646 that, if I'm not mistaken is a four cylinder. Do you know if the settings are the same on my 2.7l five cylinder?