Some white/blueish smoke while idling
 

Hello folks! It's been a while since I posted... I switched jobs back in march and well, this has been a hell of a mess, but now things are back on track and my old benz is now getting the attention it deserves.

My issue is that I'm getting some white/blueish smoke while idling in traffic or while gently accelerating when cruising. The engine is running really good though.

In an attempt to reduce the smoke mentioned before, last week I installed a set of 261 Bosch nozzles that redassag00 sold to me. The job was done by a Bosch certified shop and the results were really amazing. Lots of low end power, reduced fuel consumption and smooth idle. However the smoke is still there.

Last saturday I replaced the valve stem seals and adjusted the valves as well, with the same intention, stop the smoke. I got some nice results, specially in the morning, as there is about half of the smoke there used to be. I also changed the engine oil and all the filters. However, my problem was not solved by doing this.

I've noticed some oil comsuption between changes, about half a quarter every 3000 miles (5000 km). There are no leaks, so my bet was that the valve stem seals were the reason. However I still have the same amount of smoke in the circumstances I mentioned.

Now I'm cofused, as I beleive the rings are in good shape. The engine was overhauled about 60k miles ago and it was properly broke in...

Is there any chance my problem is engine oil mixing with diesel inside the IP? This would be a lot better and easier to solve...

BTW, I've noticed that when I leave the engine idling for a couple of minutes and the smoke starts to appear, it seems like it kind of misses a fire stroke. Not bad as a totally dead cylinder, but you can hear a slight miss and also you can feel it if you're touching the engine...

:confused: Any sort of advice is greatly appreciated

Have you adjusted your injection timing?

Yes timing, also prechamber inspection.

Thanks for the input. I'll have that in mind. BTW, can I make a drip tube from an injector line? Or do I have to buy one from a Bosch dealer? I have a pair of those lines sitting at the shop. If I can use one of those how long should the drip tube be?

As for the prechambers, I understand the pintle or ball should be complete and with a smooth surface. However, how big should it be? Any sort of measurement that can be done?

Now, what do you think about a possible oil leak inside the IP? Is it possible that the engine oil gets into the fuel gallery in the IP?

I think you can make one from an old injector line, some people I think even do it with no "drip" line.

As for the pre-chambers, just make sure your balls are in place. :D

Ok. I'll make a drip tube from an old injector line. I'll check the prechamber as well. If the balls are in place, it would make no sense replacing the prechambers, right? Or should I replace them if I can get them for a reasonable price?

Any thought on my theory of the oil leaking into the fuel gallery in the IP?

You wont get them for a reasonable price. You seem dedicated enough to the cause, you may want to pull them and check for cracks. I assume this smell does not smell like glycol and goes away under load?

Oil mixing and getting into the IP seems unlikely. But I'm interested in this thread, because I, too, have a little white/blue smoke on idle and initial take off, even on Bio. IP timing and new injector nozzles from Sean Watts are on the immediate list. Good luck, but I'm tuning in to see what's causing your symptoms.

I would the do the IP timing before you check the Pre-chambers.
There is a guy on Ebay that sells the drip tubes that he makes from used Fuel Injector Lines. Take a look at the picture of his and you will see what yours should look like.
Also replacing the Pre-chambers requires some special tools so Pre-chambers are not a routine removal item.
What I am wondering about is if there is 60 thousnd miles on an overhauled engine why the Valve Stem Seals would be shot; were the OEM seals or after market seals.

It occurs to me, couldn't you get a fuel sample on the delivery side of the IP and have it chemically analyzed for traces of motor oil?

Has anyone ever seen an IP leak into the fuel?

Im tuning in too... Ive already:

- rebuilt injectors with Bosch nozzles at a Bosch shop
- adjusted timing to 24.5 BTDC
- checked chain stretch (3 degrees off)
- burn 1/2 quart of oil per 1k miles
- no disappearing coolant

And Ive got the same thing - mostly whitish, very slightly blue smoke on startup. not a huge objectionable cloud, but visible.

FWIW it *worse* running bio. anyone else notice this?

Car runs like a champ, purrs and gets 27 mpg.

id love to figure it out...

dd

Thanks for your thoughts guys.

Winmutt, no glycol smell at all and yes, it goes away under acceleration, specially hard acceleration. It only smoke at idle or under very light acceleration and only for a couple of seconds, maybe 5 or so...

Griesl and DieselDan, if a get any further information on this I'll keep you informed. Later today I'll have a chat with a diesel technician at my job. Even though he is a Toyota guy, I'm pretty sure he'll have some advice for me. He has been in the business for 30+ years, so he knows old diesel systems.

Diesel 911, I'll take a look at the auction. Regarding the valve stem seals, I don't think the old seals were completely shot. However I had to do a valve adjustment, so I decided to give it a try and change the seals. I got a really nice set made by Ebi Bilstein for only $20 from a local provider. Very good quality and actually the exhaust seals are coated with something that seems to be ceramic and the lips are made of a funny looking green rubber-like material which I'm pretty sure is not rubber...

I'm still suspecting this has something to do with the IP. Another curious thing I've noticed is that when I put a bottle of cetane booster when I fill up the tank, the smoke seems to go away completely. My theory is that if somehow the engine oil is getting into the fuel gallery, the cetane content will be reduced and therefore the pop pressure and the prechamber temp is not enough to fully ignite the diesel mist. Does this sounds reasonable to you?

Dan, I am bewildered by the same thing--"worse" on bio. Every once in a while, I'll top off with petro to see what kind of mileage I'm getting with bio (I don't have a hose gallon meter), and if I get over 60% or so with petro, the smoke kind of goes away--or at least you really have to look hard for it. I have heard that timing should be around 26 or 27 running veggie or bio. Is that true?

GRIESL,

glad to hear someone else is experiencing this change when on bio.

I have heard on this forum that timing for B100 should be 25 deg BTDC, and for WVO should be 26 deg BTDC. How correct those numbers are I do not know.

Since the factory spec for timing is +/- 1 degree, when I adjusted my timing I put it at 24.5 degrees. I did my best considering the obvious shortcomings of the drip method, but I think its right on.

So I think the problem is timing related. I should re-measure my timing chain stretch using a dial indicator. If its near 4 deg Ill put in a woodruff key - Id be very interested to see if that made any difference.

dd

Pre injection in cold weather will make for really hard starts.