1.) I have an 82 300CDT with 207,000 miles that I ran a can of Diesel Purge through. The fuel coming from the return line (in the jar of Diesel Purge) turned the Diesel Purge black. I thought that maybe the engine was just really dirty, so I ran another can through, but the same thing...black fuel coming from the return line. Looks as if there is oil in the fuel. Does this mean I have a potentially bad engine?

2.) Also, there is this mystery part I can't seem to figure out where it goes. It's hanging from the right side of the engine near the starter. It's orange, has a a thick wire attached to it, is orange with two holes on the end and screws into something. I just can't figure out what. I've taken a picture of it, if anyone would like to see what I'm talking about, just let me know.

Any help on these two questions would be greatly appreciated.

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James Duffey
Atlanta, GA
1963 MGB
1972 300SEL
1980 240D
1989 300SEL
1995 E300D
2000 Audi S4

Greetings,


I wouldn't say you have a bad engine. Fuel going back into the jar is overflow that the injectors couldn't inject into the engine because of engine speed or load. You say the purge turned black or a very dark green? The original color I hope when you started was a orange to brown, was it? If your purge turned instantly black, and normally through the clear return line in it's operating mode,without the purge it's a yellow, isn't it? If you can please describe normal operating color before you purged the engine,fuel returning through the clear line to your fuel tank and also color of fuel going into prefilter.
If you can email pics of this tangling wire and we'll find out where it goes for you.

Charles

Hey Charles,

The purge was clear with an orange-ish color when I started the engine to run the purge through it, but the fuel coming from the return line had a much more black tint to it. After I purged the engine and drove it a while I noticed that the pre filter also has a faint black tint to it. I replaced the pre filter when I purged the engine. The old pre filter was not a see through type.

I have an 80 240D that I purged at the same time but didn't have this problem. I was thinking maybe the tank has an algae problem, but shouldn't the color be more green than black? Could it be that the engine is just really dirty? I've only had this car about two months and don't really have much of a history on it. I know the previous owner didn't know much about diesels and most likly never used anything like Redline or Lubro Moly products.

Greetings,

I am assuming you installed a clear prefilter before doing the purge on your engine. Was the color of your fuel at that time a yellowish color or leaning more toward greenish black? When you purged the engine did you do it from under the hood with supply and return lines into the purge jar, or did you do it from the fuel tank connecting lines? If you did it all from under the hood, you only had a very small amount of fuel left in the system, especially if you primed the fuel out of the filter and sucked in purge before starting the engine. The purge while traveling through your fuel system made contact with the IP internal parts like pump plunger, springs, seals etc. It also made contact with your upper spring and pressure valve in the output pipe connection. I'd say it's quite possible that some of these parts were perhaps gummed up or dirty and as a result you got the garbage back through the return line.
What color is the fuel that the primary filter is running through it now?
I hope through it all you found a performance gain.

Charles

I'd like to see the photo of the mystery part. I won't get to see it till I get to work on Monday, but I'm willing to bet the mystery part is the connection to the block heater. Trace the wire coming from it, it will probably lead to a plug that you can plug into a wall outlet. I've run the purge several times and noticed the purge turning black. I think its from carbon that's built up in the system. I would not worry.

__________________
2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
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'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

While a friend was visiting today, I had him to look under the hood in the direction of the mystery wire while I crawled underneath the car and gently tugged on it. The wire is the block heater. Thanks! But, where on the block should it attach?

When I ran Diesel Purge through the engine I connected it directly to where the fuel exits the pre filter, so there was no existing fuel in the line, just Diesel Purge. What came out of the return hose was a blackish color. I guess the engine is just really dirty. The old pre filter was white plastic, so I wasn't able to see inside it. The new one is clear and already has a few particles in it, but the fuel in it appears yellow-ish. I ran two cans of Diesel Purge through the engine and the fuel from the return hoes was still a little black. Should I run another can through for good measure?

Greetings,

I wouldn't bother running another can through. The diesel fuel in the next few days will carry away the dissolved deposits and carry them back to the fuel tank to most likely be dissolved in time and refed to your filter. The preheater cord gets plugged into the heater located under the intake manifold where two prongs should be sticking out of the block on a threaded looking large brass looking bolt.


Charles

I would like to ask about the different and acceptable ways to purge a system. I have heard about the jar method that is used by pretty much everyone so far and is listed on the Lubro-Moly can. However is it possible to 1) poor the can into your fuel tank 2) poor it into the primary fuel filter to prime the system and clean it at the same time. ?

The reasons I ask about these 2 methods is because there is very little chance you will skrew up and suck air into the system.

Also, is it recommended to change the clear fuel lines before or after purging the system? I just bought the 3 lines along with the gold fittings attached to them... the current ones are very dark brown. Your help and comments would be much appreciated.

I was going to ask the same question about putting diesel purge directly into either the main filter or in the tank. My mechanic said to take off the main fuel filter, drain out the diesel and fill it with the injector cleaner. This way the injectors get an immediate shot of pure cleaner. Also he suggested that every 4 or 5 fill ups, put in 1 quart of transmission fluid in the tank. I have read the instruction for Lubro-Moly and like silverbullet said it would seem easier to just put the purge in the filter.

__________________
1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

Well I purged my 240D yesterday and it wasn't all that bad. I think it really helps to have two people present. One to adjust the throttle and one to hold the jar. I just let the purge suck through the secondary filter to the pump vs. running a 1/4" hose from the pump. The bottle says to run it at various speeds but I am curious what approach do you guys use? I did leave about 20% of the purge in the bottle because I wasn't going to risk sucking air in the system the first time. The next time I will be less conservative.

I also changed those clear fuel lines with new ones... I had a hard time starting the thing even though I pumped it for like 7 minutes. I was expecting the car not to smoke after I purged it... but it did. I've heard diesels smoke no matter what, but on the freeway it seems like some smoke more than others. I figure mine is smoking too much if I can see the exhaust in the headlamps of the car behind me. Perhaps this is not a good measure...

Since I haven't had the car since new, it is really hard to know what is normal exhaust flow. I am thinking about purging it along with my routine service of 3,000 miles. Is this overkill where it might do more harm than good?

Thanks for the comments everyone... it really helped.

SB

Greetings Silverbullet,

I have to say I had a smoky diesel, either it was oil during start-up or black during idling. I have to admit, it had me confused until I finally decided to start with all the tune-up procedures and see where it got me first before declaring a tear down of the engine. Glad I did too. Obviously I changed the main fuel filter first, although the clear strainer looked clear, I didn't chance the spin on because you can't see it's condition. I readjusted the valves, twice, forgot to do the valve seals the first time, so it was practice for the second go around. I also found that my vacuum pump diaphragm had a small hole in it pumping under vacuum engine oil to my air cleaner assembly. A new rubber diaphragm cured oil in the filter housing completely. I was still getting a little oild burning at start up and still black puffing at idle, but decided to check IP timing and found it to be off some 14 degrees. Only being able at the time to adjust the pump to 15 degrees BTDC without a few gaskets which should arrive tommorrow. I achieved a no smoke start up and running condition as well as gain 2 mpg and once again oil consumption has drop in half again. What do you think the other 9 degrees of adjustment will bring after I remove the IP and reset it to spec? I look for another 2 mpg or 28mpg total and total performance from a dead stop.
I purged my injectors after all this was done and the purge that returned to the jar was the same color leaving, tells me I probably wasted the money on the purge, no carbon buildup in the injectors to report. If the return fluid is the same as what was sucked in, your problems are most likely elsewhere in the engine or fuel system. Do the adjustments first, purge is not a cure all but only a injector cleaner. If you're still getting heavy smoke, it's getting fuel most likely to lat to burn it all. Check your IP start of fuel delivery on NO. 1 cylinder.

Charles

this sounds like some great advice. i'm a novice and was wondering if you could translate the mechanic speak.

what is IP start of fuel delivery? how about IP timing? BTDC? also, when you talk about adjusting the valves, are you talking about the EGR valve?

thanks

IP = injection pump - read up on the thread that talks about diesel injection pump start of delivery. BTDC = before top dead center. Adjusting the valves is talking about the intake and exhaust valves that are in the cylinder head and are driven by the cam.
Jim

Greetings All,

Thanks Jim for setting my abbreviations out in long form, been off today and had a many things to accomplish, and didn't get to the bit box till now. All the above items I listed above did a world of good to eliminate the oil burning as well as the black smoke from pouring out the tail pipe. If you are wanting to clean your injectors, do it by the jar method so you get a straight hit of purge that's not diluted by fuel. It can all be done under hood, but in some cases it is handy to have an additional piece of fuel line so you're not cramped for space on line length. I also primed the remaining fuel that was in the filter to another jar I discarded, so on start up it was primed solely with purge. Whether you run all the purge out of the jar is up to you, but I just kept moving the jar to suck out the last of it, didn't have any left when finished. The engine will run for about 30 seconds or so with what is left in the line after it appears to be empty. This seems to be plenty of time to either turn off the key or push the stop lever on the engine. If you suck a little bit of air, doesn't matter, you have to reconnect the fuel lines anyway after you're done, and reprime them, so it will rid the system of air at that time.

Charles

I mean no disrespect at all, I only want to compliment you Charles.

From the moment your diesel was delivered to you until now, it's nearly a phenomenon . I was not sure you were ever going to get that diesel started, and now you offer some of the best tech advice on the Mercedes Shop.

You are truly a great seeker of knowledge.

I am very impressed.

Patsy