Hi,

For the last few weeks I've had a knocking problem in my 82 240D. Whenever I hit mid throttle under a small amount of load, I'd get clatter. Idle was fine, wide open fine. I had this problem last year on my first tank of ULSD. I tried a lot of things and finally removing, disassembling and cleaning the injectors got rid of the clatter. BTW, I burn WVO off and on with a two tank system. Also, tried valve adjustment and pump timing to no avail.

A couple of months ago, it started again. I pulled the injectors and they were dirty. I cleaned them. Still clattered. I tried cleaning all the spooge from the intake. Still clattered. Tried B20 and the STP diesel cleaner you put in the tank. Still clattered. Cracked each injector and it seemed that the clatter was in all the cylinders.

Well, I bit the bullet and bought two cans of diesel purge after hearing all the hype about it here and at other places. I never thought much of snake oil but I was getting pretty desperate. I could just picture the hole forming in the crowns of the pistons. And it is hard to tell people how nice a W123 is when your car sounds like LaMachine.

Anyhow, it worked. During the purge it went away. I didn't have my hopes up because I figured that Diesel Purge must have some anti knock additives. But I've put about 20 miles on the car after the purge and it is still sounding good.

No, it didn't stop smoking when I gun it. No it isn't too much smoother. But YES the clatter at tip in is gone! Oh yeah, and that thing about changing filters because of all the "dirt" it frees was not true for me. I watched the returned fuel in the clear bottle and it never got dirty. Very clear in fact. Whatever it cleaned got burned or was dissolved.

That was some expensive juice. Anyone have any ideas what it cleaned? I thought the fuel was too burned to clean the prechambers...maybe ignorant here. My injectors were clean. All I can really think of is all that WVO is gumming up my IP. My car gets addicted to it in that I burn it and it runs well then when I switch back to ULSD it clatters. Having a dry spell of oil I've been running ULSD lately and had the problem.

The WVO has made a sticky mess out of my filter rig and jugs. Could this same stick be messing with the pump?

So at the risk of sounding like a snake oil idiot (the kind I used to think posted here) Diesel Purge worked for me!

Another free ad for Diesel Purge. And again by someone with just about 100 posts... Will we ever hear from this guy again or was this the only purpose for this login?

Don't waste your money on products that don't work when tested by automotive engineering standards organizations.

Your posts on "cleaning your injectors" are not convincing. If you clean and test your injectors as described in the factory manual and that doesn't solve your problem then the problem is in your head and that is the only type of problem that DP could help you with.

DP isn't snake oil in my view. It's a powerful, high-cetane solvent mix that dissolves carbon and petroleum-based crud. VO is known to cause all kinds of problems and waxy residues in the fuel system is one of them. As I've said before, if you're concerned about the environment, use biodiesel. Just a suggestion.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

If you clean an injector by the book you will see that obviously there is no way that any solvent run through your system could ever do the job.

Read the book.

Agree'd, although you should continue your statement adding "as good as a manual cleaning will."

To say that DP has no place in your tool box is incorrect as in some instances it is helpful.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Manual cleaning of injectors (which I have done BTW) only cleans the injectors. DP has the chance to clean up the entire fuel system (for example if you have waxy deposits from VO use) and it may even help clean up prechamber deposits.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I hear it also aids in dissolving the carbon deposits on piston crowns... of course a nice Italian tune up should do the same.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

You are working from assumptions that these are good things that you mention. In fact, there are places in your system that are meant to never be disturbed unless the system is torn-down. If the system was designed to be cleaned by solvents, the manual would tell you how to do it - it doesn't because it wasn't.

Don't waste your money on products for your car that are not recommended by your manufacturer or at least some automotive engineering standards organization.

It's your money and time and your car. Waste what you want to waste. Playing mechanic is fine if that is what you want to do. Use DP and you may get to play alot of mechanic and even pay some real mechanics, real money.

TK, enough with the manufacturer propaganda. You should check out the Fuels & Lubricants section of the TDIclub. I think you'd make a lot of friends there. There's a lot of people absolutely fanatical about following manufacturer's recommendations to the letter, even beyond the car's warranty. As to Diesel Purge, I know the local professional MB mechanics use it and recommend it and it's made by a reputable German company. As far as I know, MB doesn't make any recommendation regarding DP. You seem to be saying that MB prohibits the use of DP which is untrue. BTW, DP is mostly diesel fuel, with some strong cleaning additives. I have yet to hear of anyone suffering anything bad from the use of DP. In the worst case, it won't help, but it is known to help in some cases.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I was sceptical but I've used it, and it has indeed reduced knocking from cylinder 1.

Of course I should really just take the car and get the injectors cleaned and pop-tested, but thats for a later date.

DP will probably do a good job if the problem is a nozzle that's clogged with carbon. If it's worn from old age, then no cleaning product will fix the scars.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I posted the MSDS for DP in a past thread. The ingredients are not impressive.

Instead of trying to read between the lines in my post, read the manual. Take apart an injector and look at it with magnification. It is easy to see that DP is not going to clean your injectors.

Consumerism is deeply ingrained and difficult to get past, you can do it if think for yourself.

Thanks for the offer but I don't have time for more friends, good info is what I come here for.

This is a totally false statement. You really should check into this better before you give bad advice.

Are you saying that DP is a complete scam, and the people who noticed improvements in engine operation after using it were hallucinating?

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

I am saying that you need to read the factory shop manual, you and other MB owners. You could also read the MSDS sheet for DP. After you feel like you know a little about your fuel system, take apart an injector and look at it with magnification.

If you still think DP is worthwhile, look inside an injector before and after a DP treatment.