The engine in my car perfect until about a week ago. I filled up the tank and the next day it starting making that knocking sound. Not alot, but it's there. I checked under the hood and one of the little return fuel hosed coming from the third injector is wet. The sound has eased up a bit over the last week. Could it be a bad injector?, Bad fuel? Any Ideas? andy

Andy,

First, on the fuel leak. Since one line is leaking, you might as well replace all of the return lines AND the end plug. You can buy the line (sold by the meter) from your local MB dealer. Also, there are two types of end plugs, one has a metal cap, the other is just a rubber plug. I highly recommend the one with the metal cap in it. Much lower chance for failure down the road. It's a bit expensive ($17 or so) but worth it in my opinion. Replacing the lines is an easy job, just be very careful (don't yank the old lines off the nipples on the injectors, they are fragile and will break off, you need to take a razor blade and slit the old line at the base of the nipple and gently ease it off). Once you have each line off, just measure the right amount of new line needed (using old line as a basis) and cut. As for the noise, if you hear a "ping" under acceleration, that would be a bad injector nozzle. One temporary cure is to run a bottle of Red Line Diesel Fuel Catalyst through the fuel system (just pour it in the tank). Be weary though of rebuilt injectors, even from MB, most of the time when we test them, we find the rebuilds are poor and the "new" nozzle is no better than the old one you took out.

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Regards,
Aaron

Thanks Aaron, I will replace the lines, however I did replace them all only about a year ago. But, they are cheap. So I'll do it again. How about the pinging sound? andy

I'll bet the sound is a dirty injector. I first heard it 20 yrs ago with a new 300D, I was horrified! I went to the dealer thinking I had a mechanical failure in the new car I couldn't afford.

Service manager buddy changed fuel filters and added a bottle of Red Line 500. He then told me I had just witnessed a $99.00 injector service.

It cleared up immediately and bad fuel was the culprit.

Andy,

Yes, run a bottle of Red Line Diesel Fuel Catalyst or 85+ in your fuel tank. That should clear the problem up.

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Regards,
Aaron

Thanks, I have 1/2 a tank left from the fillup that started the sound. I just poured a bottle of redline in. The sound has been diminishing on its own. I'll change filters and maybe do a can of diesel-purge also. andy

add a bottle of BG 44K which you buy at the MB dealer to a full tank. your car will clean itself out and be faster and sharper and crisper. you'll smile!

eric

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1995 E320 Sportline Wagon "Bernard"
black on black leather

http://i.imgur.com/BdZ7jM3.png