W209 CLK200 Oil leak behind alternator

[fasterblaster]

Hi,
My CLK lost about 1.5 litres of oil in 2k miles. I found the alternator was dripping wih oil.

After a lot of searching I have tracked down the oil leak to a plastic plug on right hand side of the engine block, just behind the alternator and and below the power steering pump.

Does any one know what this plug is called and how easy it is to replace.

Thanks.

 

[fasterblaster]

I got the parts diagram for the crankcase from mercedes today. Looks like there is something called a lateral oil bore screw plug at the front right handside of the engine. It's a bit hard to tell from the diagram if that is the culprit. Anyone experienced an oil leak from that plug?

 

[BlackC55]

That is the chan tensioner over bung that is leaking. It could be the tensioner seal itself.

 

[fasterblaster]

Checked with the mercedes dealer and for the M271 they only now sell the complete oil tensioner. They showed me the parts diagram and the seal it not shown as a separate part. It's not possible just to buy the seal which seems hard to believe.

 

[fasterblaster]

Problem solved.

As BlackC55 suggested. It was the cap over the oil tensioner. The cap is mostly metal with rubber inside the cap. There is a small hole in the middle of the metal cap. I guess this is so that you can push something through the hole piercing the rubber and allows the cap to be hooked out.

My problem was that someone had previously hooked out the cap then just wiped some silicone sealant over the hole and pushed it back in. The silicone had not stuck and had come away from the hole. The cap should have been replaced with a new one.

 

[stability]

Its a bit tight to pop in, just move the alternator to the side disconnecting the battery first allowing you just to tap it into the block evenly.

if it pushes right through into the block again use a magnet and small flat bladed screwdriver to carefully prise it out and try again.