pre combustion chamber inspection/removal

[sixpack]

Hi All,
Can anyone tell me how to remove the pre combustion chamber on a 605, 5cyl diesel engine? This is the 2497cc engine in the C250D The reason I ask is that have broken the hex part of glow plug in the head, OK call me all the silly fools, I deserve it!. I dont know if removing the pre chamber would help, or does the glow plug have to come out first anyway. The car still starts OK on 4, then the 5th chimes quite quickly. Ive found some references to pre chambers, but nobody has described them very well.

Peter

 

[Andy]

Hi

I think you will find that the glow plug has to come out first. To get the pre chamber out you will need a special tool. The chambers are VERY tight to come out. So unless you have the tool & arm with a slide hammer they are not moving.


Regards

Andy@mercedesservicing.com

PS

It is quite common for the glow plugs to snap off. CDI engines are even worst. No much of a neck on the glow plug. So no strength there. They seize in and the next thing you know is you have the head in your socket & the rest in the head.

Good luck!!!! But I think the heads got to come off or leave it till it won't start. DO NOT TRY & DRILL IT OUT. Ignore at your own peril!!!!!!!!!& expense!

 

[sixpack]

Thanks Andy, sounds like good advice. What actally happened was this, Try to remove No3 glow plug. It started to come out, but got stiffer the more I unscrewed it. It was very nearly out (I think about another 1 turn to go) when the hex section broke off. I used a home made tool a bit like a milling cutter with a centreing mandrel 4mm dia. This 4mm section fitted into the hole in glow plug where the centre electrode should be. (I managed to remove the electrode). What I was trying to do was cut out the last of the thread of the glow plug without damaging the cyl head thread. I managed to tap the hole in the glow plug to 5mm with the intention of using a length of 5mm stud to pull the remaining part of the shank out of the head. I havnt been brave enough to tackle this last bit yet. Im tempted to heed your advice & leave it as it is !. Youve obviously had this happen to you before, do you have any advice? Should the engine be hot or cold before trying to pull glow plugs? What about using anti seize compound (coppaslip) ? If I have to, how do I remove the pre chamber? Any advice would be greatly appreciated.

 

[dieselman]

The pre-chamber is pressed in from the underside of the head so the head needs to come off for this.

Your plug is jammed in due to carbon build up on the threads. Try heating the engine up as that will cause the aluminium head to expand more than the steel glow plug.
Obtain a purchase on the plug, a stud removal tool might help, soak the thread with release agent and then work the plug in and out.
Hopefully it will free off enough to undo.

 

[sixpack]

Thanks Dieselman, clear description of where the pre chamber is. I think Ill leave it alone for now, as it starts OK on 4. Tackle it in the spring.
Ta
Peter