For a while now I've been getting intermittent smoking on my 78 240D. It can be pretty heavy sometimes, I've had people race around me to get out of the smoke, kind of embarrassing. It's a bluish-black color. Seems like it's the smokiest on my afternoon/even commutes home, but not always, 15miles one way nearly all highway. This morning on the way in I'd get a tiny little puff on acceleration, pretty normal for an old diesel with 320k miles, but that's about it. I get a little smoke on start up but not much. I put new reman Bosch injectors in a couple years ago, though I've run around 20k miles of veg oil through them, and they started nailing a while back. Since removing the system the nailing has lessened but is still there, so I know I need to pull, clean, and pop test them. The intermittent thing has got me stumped. Engine temps are always reaching operating temps right about 90C. I've got plans to adjust the valves, which I do annually anyway, replace the diaphragm in the vac pump, and possibly doing the valve stem seals. I may also try the Marvel Mystery Oil trick in the cylinders while I have the injectors out. Any other thoughts or suggestions?

__________________

Check the vent line on the vacuum pump to see if it sending oil into the intake.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The Bosch Injectors have some drilled passages in them that over time and no periodic Diesel Purges done on them can get entirely plugged. See #14 and #15 in the pic.

I think that using Veggie Oil would guarantee that they get Plugged.
Monark and Bosio Nozzles do not have the drilled passages.

Could it be the Valve Stem Seals are allowing Oil to get by the Valve Stems and into the Engine?
Valve Stem Seal Replace 617 Hunter speaks on how Bad Valve Guids/Seals can cause blow-by
http://www.peachparts.com/shopforum/showthread.php?t=203902&highlight=valve+seals

I do not know what year they changed from Pneumatic to Mechanical Governors on the Fuel Injection Pumps.

If you have a Pneumatic Governor a bad Diaphragm or Vacuum leak in the Housing can cause some issues. There has been some within the last week to 2 months threads on that.

The Marvel Mystery Oil will work only if the Rings are sticking due to Carbon Build up. People say using Synthetic Oil; after driving 200-300 miles will also free up sticking Rings.

Attached Thumbnails

 

__________________
84 300D, 82 Volvo 244Gl Diesel

I'll check it out Kerry. I had some smoking issues before that were solved by a new diaphragm in the vac pump, so I'm hoping this is the issue. I had to swap vac pumps a while back cause the original one was failing, and I was loosing brakes. I plan on rebuilding it completely and putting it back on.

__________________

Which picture are you talking about? What is the hole for? Seems odd that some manufacturers would do it and other wouldn't. I know veg oil is hard on injectors, the original injectors has nearly 300k miles and about 40k of those were veg oil miles before they started nailing. The new ones started nailing after about 15k miles, I don't think I can blame all the nailing on veg oil.

Seems like valve stems seals should be done just cause the engine has 320k miles and they are cheap, and it sounds pretty easy to swap them.

I use the partially synthetic Delo oil, and it's been a few thousand miles since I removed the system, seems like the rings shouldn't be stuck but when I pull and check the injectors I'll drop some MMO in just for good measure.

__________________

Looks like I have a mechanical governor. The pneumatic one is in the butterfly contraption on the intake manifold, which I don't have. That must have been only a 77 thing on the 123s. I've never seen one on any of the 123's I've ever worked on, only on the 115s.

__________________

Thanks, I continue to learn stuff from the Members of this Forum.

__________________
84 300D, 82 Volvo 244Gl Diesel

The part of the pic with the whole Injector has a little circle at the bottom marked #12. To the rignt is a larger Circle parked #12 that has a magnified pic of what is in the little #$12 Circle.
Those little passages are actually drilled into the Tip of the Injector Nozzle Pintle.
I copied this from the FSM:
"The Injection Nozzles with the Bosch designation DNO SD 240 is a perforated Pintle Nozzle.
It differs from Pintle Nozzles by a crosswise bore and a longitudinal bore #14 and #15). In addition, a Maintenance-free Rod-type Filter (13) is pressed into the Injection Nozzle Holder top.
The advantage of the perforated Pintle Nozzle is better injection at lower volume and less load, as well as a reduction of coking on the ring gap."

I read somewhere that Bosch had a Patent on the drilled passages. Also in the FSM the is mention of DNO SD 240/ with the / indicating that the central passages was enlarge. This makes me think that Bosch found out that the narrower passage of the DNO SD 240 carboned up more easily.

I think that if Periodic Diesel Purges are done and the Valves are kept adjusted that it is possible to keep the passages clear of Carbon. But, on my Engine and most of the Injectors I have pulled from the Junk Yard those passages were entirely plugged solid with Carbon.
After that happens I do not think a diesel Purge will work on it.

In any event the later Bosch Nozzles have a Facet (flattened area) on the Pintle that serves the same purpose as the drilled Passages. Monark Nozzles for the 617s also make use of the Facets.
As far as I know Bosil Nozzles do not have either the Facet or the drilled passages.
So I believe the Monark and the Bosio Nozzles are constructed in a manner that they are less likely to carbon up.

__________________
84 300D, 82 Volvo 244Gl Diesel