Glow Plug W203 220CDI

[John Kerr]

I have the glow plug light coming back on after starting,I've changed many a glow plug in the past on various cars.There seems to be a problem with plugs shearing on Mercedes and reading posts on here it is suggested soaking the plugs in releasing oil for a few days is the thing to do.If a plug is fitted properly there is no way said oil is going to go down the threads.If a plug is seized it must be the carbon on the bottom of the thread.Any thoughts on this and advice from someone who has changed the glow plugs would be appreciated

Many thanks in advance John Kerr

 

[rf065]

The general advice on the forums seems to be soaking with releasing oil for a few days before & getting the engine as hot as you can before removing them. Good luck.

Russ

 

[Nick1964]

I think that there are also corrosion problems caused by dissimilar metals and an electrolyte as well as the carbonizing problem. I agree with you that if a taper seated glow plug is fitted properly it seems unlikely that penetrating oil will work its magic’. However, consensus among the forum members is that it will. I would also agree that getting the engine to full operating temperature would probably be helpful by the different rates of expansion of the steel glow plug body on the aluminium alloy cylinder head. A soaking with penetrating oil on a hot engine would make good use of this difference and done each night and leaving overnight should hopefully do the trick.

 

[exeng]

The oil will soak into the threads at the top of the plug but will not pass the taper seat at the bottom so if it is carbon that causing the issue it will not help