Topping-up oil every week becomes a job that no enthusiast likes to perform. Even something as little as a slow drip is an annoyance that is always held in the back of your mind.
The regular suspects in Mercedes-Benz cars are:
- Oil Separator
- Camshaft plugs, 30mm and 65mm
- Valve cover gaskets
- Oil filter housing and cooler gaskets
- Timing cover plug
112 – V6 that start from 1997-2005, used in C-Class, CLK , E-Class, SLK, Chrysler Crossfire
113 – V8 used from 1997-2005, used in E-Class, ML, S-Class, G-Wagen, CLS
272 – V6 used from 2004-2011, C-Class, E-Class, SLK, CLK, R-Class, Sprinter, GLK
273 – V8 used from 2006-2014, E-Class, SL, S-Class, CLS, G-Wagen, ML, GL, R-Class
Rear engine oil leaks
272/273 Engines: The most probable causes are the oil separator and cam plugs (30mm and 65mm). The oil separator is placed onto the back of bank 1 (passenger side) with either 4 torx bolts or 4 external torx bolts. Take out the oil separator, change, and clean the oil residue from the engine.
The cam plugs (depending on model, there is usually two 30mm and one 65mm plug) found on back of engine both sides. The plugs will pop out with a screw driver, and the new ones can be pushed on by hand. Just ensure they are pushed flush.
Oil leak on valve cover, spark plug wires, front and rear of engine:
112/113 engines: Valve cover gaskets and valve cover bellows leaking.
- Take out engine cover, air box and air duct tubing
- Remove coil packs T30 bolts and spark plug wires. There are two spark plugs per cylinder – the coil packs label them A and B. The best trick for getting the plug wires off without breaking them is to use a 17mm wrench.
- There is a special 17mm wrench with a bend that works great
- Take out breather hoses (they are usually brittle so be ready to replace them) from the valve covers.
- Remove the E10 Torx bolts and valve cover
- You may need to disconnect the fuel line
- Change your spark plugs now if you haven’t, you have easy access with the valve covers off
- Remove the T25 bolts from the breather covers, pry the breather covers off with a screwdriver.
- Remove all sealant from the breather cover.
- Apply new sealant to the channels of the breather cover, place valve cover down, tighten T25 by hand, the bolts are very weak and break easily.
- Change valve cover gasket and secure to engine.
- Reinstall parts. When installing the air box lubricate the seal with some lube for the mass air flow connection, this will make it a lot easier to install and you avoid cutting the seal when mounting it.
Oil leak on front of engine:
112/113 engines: The driver’s side front of engine is where you will have your oil filter and housing. If you see oil at the bottom of the housing you may require a new oil filter housing and cooler gaskets and/or timing cover plug on the timing case cover.
Oil filter housing seal
- Drain oil
- Remove oil filter
- Take out oil cooler
- Remove oil filter housing nut 46mm socket
- Replace the gaskets
- Reinstall parts, change oil filter, and oil
- Clean oil residue
Timing cover plug
- Remove two torx bolts and allen bolt.
- Replace the crush washer, cover and gasket
- Clean oil residue