Fuel Leak - PeachParts Mercedes-Benz Forum

99E300TD · #1 01-30-2007, 10:23 AM

Not near the filter... looks like it is coming from under the intake but I can't see great down there. Any common leaks in that area? I wonder if it is a mix of ULSD and the very cold weather we're having here (5-7 degrees F). It was fine until last night...

I let it sit outside in the cold and snow... about 10 seconds glow and fired right up.... no plug in. Pretty cool!

99E300TD · #2 01-30-2007, 10:41 AM

And if it is the IP - is it easier to just buy the whole new pump rather than relapcing all the seals?

rrgrassi · #3 01-30-2007, 11:36 AM

Check to see where the leak is. You may have a seal problem, or a loose injector line, or a leaking braided fuel return line.

Parrot of Doom · #4 01-30-2007, 11:43 AM

On the side of the injector pump is a small piece of plastic cylinder, with 3 fuel pipes going into it, and one electrical connector.

Put your fingers underneath it with the engine running. If its damp with diesel, then one of those pipes and very likely the shutoff valve (for that is what it is) are leaking. The O-ring for the shutoff valve is easy to replace, just remove the water bottle and undo the 2 torx bolts and off she comes. The fuel pipes can be stuck in tight, just push the horseshoe clip in and pull them off.

TMAllison · #5 01-30-2007, 12:13 PM

The other possibility is the delivery valve seals on top of the IP (x6). With a very bright light and you should be able to determine where the leak is comming from. If you need more access pull the nut and two electrical connections on the windsheild washer bottle and flip it up and out of your way so you can get a better look.

foxden · #6 01-30-2007, 03:21 PM

This is a common place for fuel leaks. The plastic tubes all have o-ring seals that age. It is definitel much less expensive to replace these parts than the pump. Do a search, and you will find all the part numbers etc. Mercedes doesn't even list the parts for the diesels newer than I think 98, but the part numbers are the same.

There is a pretty good DIY shown under replacing glow plugs, with pictures if you are interested in doing it yourself. I did all but one without removing the intake valve with the help of the posts I found.

99E300TD · #7 01-30-2007, 06:56 PM

Awesome... thanks guys... do you have the link to the pictures... I'm only an average DIY - don't want to get in over my head. On the other hand, I called a MB dealer and they want 3 hours labor just to take the intake off and diagnose the problem... at $90 / hour... I might be willing to learn!

TMAllison · #8 01-30-2007, 07:18 PM

None of the jobs discussed are really very difficult (ie: fuel lines, shutoff valve or delivery valves). I swapped in viton o-rings at the fuel lines and shutoff valve in about 1.5 hours last weekend. The IM only needs to come off for the delivery valves (unless you work at the dealer then it comes off for everything). I did delivery valves at Xmas, was my first time doing them so i went slow and spent a lot of time cleaning the gunk out of the IM too so spent a total 6 hours.

First thing to do is find your leak. Spray it clean if its too dirty to know for sure where it's comming from and then look again in a few days. Pull the washer bottle if you cant see well enough.

No damage is being done in the mean time. You will know when time is runnng out when the hard starts (air in lines) begin to occur.

sokoloff · #9 01-30-2007, 09:12 PM

and maybe if you have a choice, point it downhill when you park it.

Len

Parrot of Doom · #10 01-30-2007, 09:22 PM

See that image - the fuel shutoff valve is in the middle. The picture is taken from below. You can see an electrical connector sticking out the side. The front of the vehicle is to the left of the image.

If its leaking, or those pipes are leaking, the diesel will drip from that valve, on the bottom. You can tell by sticking your fingers underneath it - if its soaking wet with diesel, then theres your leak. You can actually see diesel leaking in that image, on the right side of the valve.

To get to it, just remove the water bottle. 2 nuts, be careful the plastic may be brittle. The electrical connectors for that bottle are easy to remove.

Its got one fuel pipe under it, and two on the top. To remove the pipes, just push the white clips in, and tug the pipes out. They can be stiff, don't be surprised if that bottom one needs serious force to remove. Just go at it steadily.

Once the pipes are off, there are two torx bolts to remove. One from the right side of that image, and the other right next to that connector, below a slight 'bump' in the plastic shape of the valve. Once those bolts are out, slide the valve out. You'll see a big O-ring (it may be inside the pump). Remove it carefully (don't let bits get in the pump), put the new one on, and reassemble.

Buy a complete new set of fuel lines - there are a few of them, its worth doing all of them at the same time. Fixing a leak on just one line increases pressure on another, its a false economy. Do them all at once.

While you're in there, check the clips on the metal injector lines that run from the top of the injector pump, between the intake manifold, and to the top of the engine. If they're brittle and broken, buy new ones. They stop the metal lines from vibrating and eventually leaking.

99E300TD · #11 01-31-2007, 09:09 AM

Thanks Parrot.... that'll get me in the right area.... will keep you guys posted (no pun intended) - may post pics of the culprit before I rip into it next week... thanks again!