Smokin'

[SHARK1007]

Gentlemen:

In search of the perfect running 617, I've had new glow plugs, lots of service, 15-50 Mobil One, new rackbolt damper, everything except injectors.

Doesn't smoke on accelaration, runs well but smokes just a little at idle, can't hardly see it. I'm using Red Line 85.

I'm a finatic, what 'ya think? Test injectors next?

It's in a 79 300 Super Dog.

[1985 300SD Sady]

Do a diesel purge, sometimes that will clean out the injectors and make the car not smoke at idle..

What color of smoke?

How much oil do you consume?

[SHARK1007]

Doesn't use oil and the smoke looks very light, hard to tell between blue and gray.

[barry123400]

Just a little may be completely normal for the accumulated milage. We all can develop hyperensitivity or fixate on things that may be in general terms normal. The 617 is not the most efficient design and was not designed perhaps for elimination of all smoke. Also ambient air temperature may play a roll as well. Notice that even new cars at certain temperatures emit visible traces from tailpipes. One could try various maintenance proceedures and lessen it perhaps even a little more. On some of my old diesels at idle I would say no visible fumes but someone else may see something. More important to me is how efficient the engine is working. Do you get better than average fuel milage? Or less? With efficiency sometimes there will be what are consider undesirable effects. One of my 240s is giving quite a little bit less fuel milage than I think it should. But there seems to be no visible emission from tailpipe at idle. When i get the problem found it will not suprise me to have a little emission at idle as a byproduct. If this problem really bugs you though it could be some wear on your valve seal rubbers has occured also this should perhaps produce a more smokey startup. How many real miles on engine? These parts do not last forever. Checking the injectors may not be a bad ideal either as mercedes quotes to pull them and check every hundred thousand miles.
How many are done? A relatively minor problem here and there does add up. The choice to correct everything may be a slippery slope if generally efficiency is good one may be better off living with a side effect or two as a money pit can be self constructed. One 5 cylinder engine I own could stand a rebuild but for my application is generally ok. Needing the rebuild does not affect reliability for my application. But would cost a lot with little real gains. You do of course have a good clean air filter?

[SHARK1007]

Barry:

I am too finatical, that's a given. I guess I'll check the injectors. It has 132K miles, new filters, etc. and gets about 20mpg with me driving pretty hard.

Odd, I have spent more on the car in repairs than what I paid for the car!

It is much better than a new 84 SD I had that smoked like it was on fire at idle and the dealer never could eliminate the smoke.

[rg2098]

Soak the injectors in carb cleaner. Works better then a diesel purge.

[barry123400]

Nothing wrong trying to get something to be perfect in my mind either. The injector checking is indicated by your milage anyways. Only wish one of my cars had just 130+ miles on it. Just was apprehensive about you trying to eliminate what you describe on a high milage engine as then many times it is a little bit of this and that with nothing specific.