2005 E320CDI Glow Plug Change - PeachParts Mercedes-Benz Forum

Randy · #1 10-11-2015, 03:42 PM

Hi, , I have a new code: glow plug cyl 6. Is changing the glow plug as straightforward as it appears to be?
Car has 150000 happy miles: performs well, uses no oil in 12000 miles. A keeper.

Diesel911 · #2 10-11-2015, 05:07 PM

Have you checked the resistance of the glow plugs with an Ohm Meter (on your Multimeter) yet?

I am not sure on your particular year but on the Engines that have Aluminum Cylinder Heads and long Glow Plugs it is common to have the hex end of the Glow Plug Break off. Most often due to corrosion between the steel threads and the aluminum treads of the Glow Plug but some have also had carbon leak into that area had the carbon stick the Glow Plugs in place.

There should be some threads on the 606 engines that have some ways to decrease the chances of them breaking. The 2 that I remember are take a couple of weeks sraying the Glow Plug with something like Kroil or PB Blaster and remove the Glow Plugs after a drive when the Engine is nice and hot.

Diesel911 · #3 10-11-2015, 05:10 PM

Have you checked the resistance of the glow plugs with an Ohm Meter (on your Multimeter) yet?

I have not noticed any Threads where someone removed the Glow Plugs on an Engine as new as yours.

I am not sure on your particular year but on the Engines that have Aluminum Cylinder Heads and long Glow Plugs it is common to have the hex end of the Glow Plug Break off. Most often due to corrosion between the steel threads and the aluminum treads of the Glow Plug but some have also had carbon leak into that area had the carbon stick the Glow Plugs in place.

When the Glow Plugs go back in coat the body and threads but not the element with Beru Glow Plug Grease or some other never-Seize type compound.

There should be some threads on the 606 engines that have some ways to decrease the chances of them breaking. The 2 that I remember are take a couple of weeks sraying the Glow Plug with something like Kroil or PB Blaster and remove the Glow Plugs after a drive when the Engine is nice and hot.

If I was going to remove the long Glow Plugs out of an Aluminun Head I would be sure I had another ride to work incase one or more broke off so I would have time to attempt removal.

Mechanics prefer to pull the cylinder head off and let a machine shop do the removal. That way they get more money for removing and re-installing the head and suffer none of the risk that they would have tring to remove the Glow Plugs with the Cylinder Head still on the Engine.

Do your Glow Plugs have 10mm or 12mm hex heads on them.

Diesel911 · #4 10-11-2015, 05:21 PM

I am looking at a parts site and they show a Glow Plug Controller "Glow Plug Controller; Glow Time Output Stage; For E320 CDI models only. Unit is located below the intake manifold" and a "Glow Plug Relay/Controller; Pre-Glow Time Relay;
This unit is the Pre-Glow Time Relay located in fenderwell area, this is NOT the glow plug controller."

So if the Glow Plugs themselves Ohm out OK check to see if all Glow Plugs are getting the proper voltage as there is 2 other components that can cause issues.

shertex · #5 10-11-2015, 05:58 PM

Apparently it's as straightforward as it appears. The PO was showing me around when I bought the car...demonstrating how accessible everything is. He changed his "just for the heck of it" at 113k miles.

shertex · #6 10-11-2015, 06:00 PM

Diesel911, this is an OM648....not the same as OM606 in terms of glow plug difficulty.

hangit · #7 10-11-2015, 06:20 PM

This forum has more information on your E320 CDI. Do a search on changing glow plugs. W211 E-Class - Mercedes-Benz Forum

John

Randy · #8 10-13-2015, 12:04 AM

Thanks everyone. I will check the resistance, etc. but I want to be prepared.
Assuming it needs to be changed: soak for 2 weeks, attempt removal with engine hot. Is this correct?

chronometers · #9 10-13-2015, 11:15 AM

Mercedes procedure is listed here (page also refers to early service campaign):

I had 2 new glow plugs installed in my 05 E320 CDI 2 mos.

The mechanic I work with recommended to do work with engine warm instead of running temperature hot as this can possibly lead to thread damage.....head is aluminum.

Definitely use a torque wrench.

X2 on pb blaster or some other penetrating oil.

shertex · #10 10-13-2015, 01:19 PM

Can any generic OBD2 reader delete the codes?

Diesel911 · #11 10-14-2015, 06:34 PM

Apparently stuff happens even to E320 CDIs.
Stuck Glow Plug Removal - Mercedes-Benz Forum

Google search =Mercedes OM648 with broken glow plugs

http://www.dailymotion.com/video/x27y6wq_mercedes-cdi-e320-diesel-seized-or-stripped-glow-plug-problem_auto
"Cylinder 5 scared me....."
http://mbworld.org/forums/diesel-forum/466006-om648-glow-plugs.html

http://mbworld.org/forums/diesel-forum/466006-om648-glow-plugs.html

chronometers · #12 10-14-2015, 11:31 PM

Quote:

Originally Posted by Diesel911

Apparently stuff happens even to E320 CDIs.
Stuck Glow Plug Removal - Mercedes-Benz Forum

Google search =Mercedes OM648 with broken glow plugs

Mercedes CDI e320 Diesel Seized or Stripped Glow Plug Problem - Video Dailymotion
"Cylinder 5 scared me....."
OM648 Glow plugs - MBWorld.org Forums

OM648 Glow plugs - MBWorld.org Forums

That is why MB specs. torque to loosen plugs at. To minimize trouble, don't exceed the torque values, use pentrating oil, and work with warm engine.

spark3542 · #13 10-15-2015, 10:38 AM

The 648 motor is much better than 606 for changing glow plugs. I've broken off a glow plug on my previous 606, then successfully changed others on the 606, as well as successfully changed GPs on my 648.

The key to success is three things...lots of PB Blaster, warm engine, torque wrench. You don't need to soak it weeks ahead, hours is OK. Engine doesn't need to be hot...warm is OK. Torque wrench is important...don't exceed about 40 Nm of off-torque. If it doesn't break free at 40, stop, spray more PB blaster, wait. repeat. It just takes the discipline to be patient.

Diesel911 · #14 10-15-2015, 09:07 PM

Quote:

Originally Posted by chronometers

That is why MB specs. torque to loosen plugs at. To minimize trouble, don't exceed the torque values, use pentrating oil, and work with warm engine.

Yes, there is a group of methods that reduce the chance of breakage but there is no group of methods that guarantees 100% success.
However, the fact that the Prior Owner changed them in the past is likely to increase the odds of easy removal.

There has even been 2 instances I have read of where people have broke of the Glow Plugs in an OM617.952 and about as many have gotten the Glow Plug body our only to find the Tip/Heater Element was still stuck in the head.
The frequency of Glow Plug breakage during removal of the longer Glow Plugs in Aluminum Cylinder heads on Mercedes is rather common.

I think you have a choice to be pessimistic (I am nearly always pessimistic about things) and plan for the worst by having another ride available or being optimistic and suffering that extreme disappointment and having to scramble to get a ride to work or school during the time it takes to resolve the issue.

Anyway best wishes.