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I'm new to MB world. New to the car maintenance/fixing world actually. Just got the 10 years old 2011 GL 350 from the previous owner who doesn't know anything about the car. Same as me. So, no doubt the the car is in the rough shape. As I tried to inspect it, I saw oil grime all over the front of the engine and drip to the ground near the front left. Especially around the belt behind the fan that has puddle of oil sit on the top of oil pan. The alternator is also covered with oil. I tried to spot the leaks and found several spots that look like where the oil is seeping from but don't know what those parts are called. So, it's tough to seek for further info. I've marked the spots with red circle (picture attached).
Please advise. I want to start with knowing the parts, so I can identify the leak spots and be able to find more information on how to get it fixed. Also, any suggestion on how to diagnose the issue properly. Don't want to take the car to a mechanic without knowing anything.
Since it's been leaking for so long, it can be difficult to locate the actual leaking points. Especially with windage and possibly even the belt slinging oil. The first thing I would recommend is to THOROUGHLY clean the entire area really well. Once it's clean, monitor it closely and you'll have a much better chance at locating the actual leaking point. Get some good degreaser, a whole bunch of cans of Brakleen and a bag of rags (use the non-chlorinated stuff to keep you from choking).
Usually the leak comes from the highest point and covers everything below it. But in this case 1 could be from your valve cover and 2,3 and 4 is rundown from your oil cooler.
That is most likely your oil filter tree.. That leaking and getting slung around by the belt.. Clean up the filter tree and see if it gets dirty again.. And there 2 spots where that thing leaks.. At the mating point to the block and itself where to the 2 pieces come together.
Thanks you all for the advices. Really appreciate that. Still have some questions :
1. When replacing the oil filter gasket, Is there any other nearby gaskets that should be replaced as well while the parts are dissembled ? So, it can be done all at once.
2. What is the part no.1 in the picture called? it's a metal part near engine oil cap.
3. Someone mention the oil cooler. From what i research, it's a common problem for this engine. Since it's time consuming and quite difficult to get in to, is there a way to know for sure that the oil cooler actually leaking? Just want to make sure before get it replaced.
Oil filter comes with two O-rings and the both go onto the filter holder / lid, which unscrews from the housing.
One is large and goes into a slot above the threaded area of the lid. The other is less than 1cm diameter, and goes into a slot at the tip of the filter lid (at the opposite or bottom end).
The circles in your 1st picture are such:
1) Vacuum pump - supplies vacuum to the brake booster. Unlikely as a source of oil leaking, although if it has been taken off and put back without gasket/seals renewed it would then leak.
2) Lower area of serpentine belt, crankshaft pulley, idler rollers - when oil leaks to the point of splashing on the belt, it then gets spun and slung all around the front of the motor.
3) Boost/intercooler hose and connector to the boost muffler - all the connections/joints/seals/hoses between the turbocharger, the intercooler (in front of the radiator) can leak bigly. Do clean and dry this area like others, and also look for split or tear in the hose itself afterword. A leaky hose can make a real mess long before it's bad enough to throw engine code or force limp mode.
4) Area between oil filter housing and high pressure fuel pump - the HPFP is unlikely to leak much oil unless it was removed and improperly reinstalled. The oil filter housing (tree) does have additional O-ring seal under the flange mated to the engine block, and they are known to leak as well.
On the front of your alternator, if the oil/grease has attracted enough dirt to from crusty buildup be careful to brush or wipe it off/down/away, rather than using a pressure wash wand and so blowing the abrasive gunk into the alternator. It can destroy the brushes / internal parts of the alternator, making you go down a rabbit hole you're not ready for yet.
03-02-2021, 11:58 PM
