Troubleshooting white smoke from an OM617

[CenCalBenz]

Hello all

My 1976 300D w115 Has a white smoke issue. The smoke is not sweet and stings the eyes in a way, also leaves a distinct petroleum stench on me and in my nose. I have concluded it is unburnt diesel.

I have performed a diesel purge which did help quite a bit.
The car still smokes a lot upon start up but does go away after driving it hard for some time.

I noticed something interesting after driving the car around today. I let the car idle for awhile after driving it and the white smoke returned after 15-30 min later. Note the car was not shut off.

My theory is that the valves are out of adjustment and when the top end of the engine(the head and valve train) get hot things fall slightly back into specification and the valves open and seal correctly.

That or the injectors are just shot.

Any ideas? I love this car and would like to keep driving it without getting an excessive smoke ticket.

[vstech]

#1 I'd adjust the valves.
#2 I'd pull all the injectors and have them tested.
when the leaker is found, new nozzel installed, before putting it back in, install new heat shields!

[kerry]

Check to make sure there's no oil in the plastic vacuum pump vent line that goes from the vacuum pump over to eithe rthe air cleaner or the intake manifold.

[barry123400]

As the head warms up I suspect the valve clearances actually become less as the valve stems expand. Especially the exhaust valves. Check the clearances and adjust where required. Some of these cars have not had this normal maintenance requirement performed in an excessivly long time. Should be checked every 15k and if seriously out the first time you do them. Check them again a thousand miles later.


I too suspect your issue is going to be injector related though. They are supposed to be checked on a hundred thousand mile cycle. Again many are never done until issues like you have raise their head. Doing the valve adjustment and getting the injectors pop calibrated etc should make the car run much better.


I personally would let the engine idle until the offensive smoke appears. Loosen one injector line at a time at the injector and see what one stops the smoke. You may have to wait a little for the cylinder to clear itself before tightning the line back up and moving to the next injector in line. That way you would know what injector was the prime offender before extracting them . This of course only after a valve clearance check.

[CenCalBenz]

Originally Posted by barry123400

As the head warms up I suspect the valve clearances actually become less as the valve stems expand. Especially the exhaust valves. Check the clearances and adjust where required. Some of these cars have not had this normal maintenance requirement performed in an excessivly long time. Should be checked every 15k and if seriously out the first time you do them. Check them again a thousand miles later.


I too suspect your issue is going to be injector related though. They are supposed to be checked on a hundred thousand mile cycle. Again many are never done until issues like you have raise their head. Doing the valve adjustment and getting the injectors pop calibrated etc should make the car run much better.


I personally would let the engine idle until the offensive smoke appears. Loosen one injector line at a time at the injector and see what one stops the smoke. You may have to wait a little for the cylinder to clear itself before tightning the line back up and moving to the next injector in line. That way you would know what injector was the prime offender before extracting them . This of course only after a valve clearance check.

Thats a good Idea, I will try that too after the valve adjustment of course.

From what I understand the whole injector does not need replacing correct? Just the pin/needle and the nozzle.

[vstech]

the injector may just need cleaning and the pop pressure set, but likely you have open nozzels.
you should also check the chain stretch and the injection timing. that will CERTAINLY produce smoke!

[CenCalBenz]

Originally Posted by vstech

the injector may just need cleaning and the pop pressure set, but likely you have open nozzels.
you should also check the chain stretch and the injection timing. that will CERTAINLY produce smoke!

The smoke being caused by the injectors would make more sense though. I do see a consistency in the time the smoke goes away after driving x amount of miles to get the coolant temp up to roughly 175*.

Dont talk about timing chains. That scares me.

But seriously, how intensive would a timing chain job be for a weekend DIYer with moderate mechanical abilities if mine were to possibly be shot.

[CenCalBenz]

Originally Posted by vstech

#1 I'd adjust the valves.
#2 I'd pull all the injectors and have them tested.
when the leaker is found, new nozzel installed, before putting it back in, install new heat shields!

Sounds like a good approach. Thanks

Originally Posted by kerry

Check to make sure there's no oil in the plastic vacuum pump vent line that goes from the vacuum pump over to eithe rthe air cleaner or the intake manifold.

Ah I forgot to mention that I did check for oil there already. The hose going into the intake was as dry as a bone.

[barry123400]

Originally Posted by CenCalBenz

The smoke being caused by the injectors would make more sense though. I do see a consistency in the time the smoke goes away after driving x amount of miles to get the coolant temp up to roughly 175*.

Dont talk about timing chains. That scares me.

But seriously, how intensive would a timing chain job be for a weekend DIYer with moderate mechanical abilities if mine were to possibly be shot.

Just a check easily done when you have the valve cover off to do the valves. You just want to make sure the chain is not stretched beyond reason and examine the chain guide for excessive wear. Chances are they will still be okay. You still want to know if they are not of course is the reason for the exercise.

[CenCalBenz]

Im going to adjust those valves this weekend and have the injectors pop tested.

While I am in there I will also inspect the timing chain.

Thanks for the help guys

[Diesel911]

Originally Posted by CenCalBenz

Thats a good Idea, I will try that too after the valve adjustment of course.

From what I understand the whole injector does not need replacing correct? Just the pin/needle and the nozzle.

The Injector Nozzle has 2 mated parts to it. The Pintle (needle) and the Nozzle Body. That is normally the only part that wears out.
However, it is not unknown for the Spring inside of the Injector to break.

This may not be your issue but I will add it any way.

When I re-installed my Fuel Injection Pump on my Volvo Diesel I got a large volume of pure white Smoke. And, it smelled like Diesel Fuel.

I looked this issue up in some of my books and found that it said the white smoke was either un-burned atomized Fuel or from Coolant.

One of the causes of un-burned atomized Fuel is late timing. Re-doing the Fuel Injection Pump timing cured my problem.

[CenCalBenz]

valves are adjusted now! It took me awhile because I had to find a good way to turn over the engine. I went on a wild goose chase searching for the proper power steering belt. The old one was worn and glazed so it would just slip.

The smoothness of the engine over all is just wonderful! I am really satisfied, but it didn't really seem to help with the smoke issue. If anything it made it kind of a grey color.

I know that the next suggested step for me is to pull the injectors and have them tested. What if i took the nozzle bodies and pintles and put them in an ultra sonic parts washer full of diesel purge?

Also BTW, what nozzles are recommend or at the very least, is there a brand I should stay away from?

Thanks

[CenCalBenz]

Originally Posted by barry123400

Just a check easily done when you have the valve cover off to do the valves. You just want to make sure the chain is not stretched beyond reason and examine the chain guide for excessive wear. Chances are they will still be okay. You still want to know if they are not of course is the reason for the exercise.

I poked around in there and could not see any wear and the chain seemed tight.

The cam lobes seemed to have been worn from the excessive tightness of the valves. There was really fine shavings stuck to the sides of some of the lobes. I don't think this is anything to be really worried about at the moment?

[kerry]

It would be very helpful if you posted a video. A recent smoke issue was properly diagnosed after a youtube video was linked to the thread.

[whunter]

Originally Posted by CenCalBenz

valves are adjusted now! It took me awhile because I had to find a good way to turn over the engine. I went on a wild goose chase searching for the proper power steering belt. The old one was worn and glazed so it would just slip.

The smoothness of the engine over all is just wonderful! I am really satisfied, but it didn't really seem to help with the smoke issue. If anything it made it kind of a Grey color.

I know that the next suggested step for me is to pull the injectors and have them tested. What if i took the nozzle bodies and pintle and put them in an ultra sonic parts washer full of diesel purge?

Also BTW, what nozzles are recommend or at the very least, is there a brand I should stay away from?

Thanks

Note:
Cam lobe angle for each valve being adjusted is critical.
Valve adjustment OM615, 616, 617 FYI.


If the valve adjustment was put off to long:
Carbon builds up on valve and seat = the valves must be adjusted multiple times with an Italian Tune-up between each adjustment.

Three adjustments on the same engine within one day is not unusual for a poor maintenance vehicle.

You should only need to be this intensive "once" with an unknown maintenance vehicle.



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