Spark Plug Coil recess full of oil.

[John77]

The car engine had an occasional miss on start up, so I thought that I would change the spark plugs. On removing the coil I found that the spark plug hole was full of oil, see photos.
I take it that is the oil cap seal. The question is that there are 2. One inside the cap and one below the cap on the engine. Do they both need changing? Does the one on the engine also seal?

 

[Wighty]

The car engine had an occasional miss on start up, so I thought that I would change the spark plugs. On removing the coil I found that the spark plug hole was full of oil, see photos.
I take it that is the oil cap seal. The question is that there are 2. One inside the cap and one below the cap on the engine. Do they both need changing? Does the one on the engine also seal?

View attachment 78261

View attachment 78262

I’ve had this on my CLK as well .
Was the oil in every spark plug recess ?
The bolts that hold the coil down also hold the rocker cover down (11nm each bolt?) around each spark plug recess where the black plastic rocker cover meets the metal below is a rubber gasket . If the bolts aren’t torqued correctly the gasket can let oil into the recess .
The oil cap is only a few quid , so change that if it’s just the plug hole by the oil cap . The seperate rubber seal in the picture goes under the oil cap , when you examine it you will see that it is shaped to divert oil spill away from the plug recess to the outside of the engine (and should be positioned to do this ) . Maybe buy a new one of these as well ?

 

[Wighty]

Also on the M271 engine check there is no oil in the electrical plug to the round cam magnets on the top front of the engine .

 

[John77]

Also on the M271 engine check there is no oil in the electrical plug to the round cam magnets on the top front of the engine .

Thank you for that. I actually stopped on first plug, so haven't looked at the others thinking that it was from the oil cap, so didn't think that I would change the plugs until I had bought a new cap/neck seal. I do normally add the extra cables to the cam mags, but have not yet. I have only had the car a few months, so slowly getting things done. I will check the cam mags now.

 

[John77]

The cables on the cam mags are different to the other cars I have had. Do these need the extra cables added to stop oil ingress?

 

[Wighty]

I’ve not seen those cam magnets before , so I don’t know .
Looking at your gearbox atf tube , it’s never had a gearbox service . Recommended every 40k miles

 

[John77]

I’ve not seen those cam magnets before , so I don’t know .
Looking at your gearbox atf tube , it’s never had a gearbox service . Recommended every 40k miles

Full service history and the gearbox has had regular service. It A CGI engine which is so much more economical that my last eclass.

 

[Wighty]

Full service history and the gearbox has had regular service. It A CGI engine which is so much more economical that my last eclass.

Weird , because the black tab on the gearbox cap is factory fitted , they change them to red when serviced by MB . Unless the broken black tab was refitted after a non MB service

 

[AndySlade]

Given that it is right next to oil filler opening and I had similar on my daughter’s golf, I’d suggest someone did not top up oil carefully or use a funnel.

 

[John77]

Given that it is right next to oil filler opening and I had similar on my daughter’s golf, I’d suggest someone did not top up oil carefully or use a funnel.

It wasn't clean oil.

 

[arion]

Weird , because the black tab on the gearbox cap is factory fitted , they change them to red when serviced by MB . Unless the broken black tab was refitted after a non MB service

Most indie workshops reuse the transmission cap

The car engine had an occasional miss on start up, so I thought that I would change the spark plugs. On removing the coil I found that the spark plug hole was full of oil, see photos.
I take it that is the oil cap seal. The question is that there are 2. One inside the cap and one below the cap on the engine. Do they both need changing? Does the one on the engine also seal?

Start with a new cap if there is oil around the filler neck.

If there´s more oil down there after a few days then replace the gaskets underneath the valve cover.
(Gaskets around each spark plug and the main valve cover gasket)

 

[John77]

Most indie workshops reuse the transmission cap




Start with a new cap if there is oil around the filler neck.

If there´s more oil down there after a few days then replace the gaskets underneath the valve cover.
(Gaskets around each spark plug and the main valve cover gasket)

Thank you.