When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Our 2010 ML350 Bluetec has developed a pretty significant fuel leak the past few days.
I could see fuel dripping from under the car while running so I crawled underneath and it appears to be coming out the transmission inspection hole where I believe the oil cooler leak also comes out.
I tried replacing the fuel filter since it sits in the engine valley but that wasn’t the problem.
Are there any fuel lines that run through the valley of the engine that would leak out the back like ours is doing?
I am trying to find a fuel line diagram to trace the lines and find the leak, but any tips or suggestions would be greatly appreciated.
Are there fuel odors from under the hood? Along with the fuel filter I would say the next likely culprit could be the short rubber hoses going to and from the filter, assuming your ML is like the W211. They do tend to split over time. Other fuel lines (supply and return to tank) usually run along side the engine/transmission. Also, are you sure it's fuel that's dripping?
So I dug in deeper and found the leak. Yesterday I went for the easiest place and pulled and replaced the fuel filter. Unfortunately that wasn't the probly, but at least we have a nice clean new fuel filter. I found a Mann filter at Napa for $79, vs $140 at the dealer.
This morning I tackled it again and traced the fuel lines from where they came up to the engine and started with the pump, to the filter, then the right side rail, injectors and return lines. No obvious leaks.
On the driver or left side I realized I couldn't see the injectors so I pulled the filter housing and the insulation. And there it was. The last injector was wet.
I looked up how to remove the return line, and found the O-ring was pinched flat in one spot. I couldn't find one at O'Reilly so I called the dealer d they had them for $3.50 each. Ouch. But I appreciate that they had them in stock.
While I was replacing the O-ring I noticed that the valve cover is designed so that fuel spills are funneled into the center of the engine so it doesn't leak onto a hot exhaust. Smart. And that explains why the fuel was leaking out the transmission inspection hole.
So a new O-ring and the leak is gone. I changed the air filters while I was in there so that's done.
So that's the second repair that came down to a bad o-ring. And both were caused by mistakes by previous mechanics.
So kudos to my wife for noticing that it was taking longer to start than usual so we caught the issue before something bad happened.
Cheers,
Ian The offending o ring. You can see the drain just past the injector
09-14-2018, 01:44 AM
