Smoke!!
 

Hi there,

I have an '83 300SD that just turned 200k. Over the past few weeks I have noticed that sometimes at red lights, it will start to smoke. When I pull away there is a cloud of smoke and then it's back to normal. Until two days ago.
I had stopped at a stop sign and noticed the cloud forming and wafting by and thought "here's my cloud again". I pulled away from the stop sign and sure enough, a cloud of white or light grey smoke. Very light color and it smells like burning oil. It did not go away and belched out a cloud of smoke the rest of the way home. Also seemed to lack power. I spoke with a mechanic that seems to know his MB's and he suggested that the tranny modulator valve had crapped out and it was burning ATF. I disconnected the hose going to the modulator and it appeared to be fixed. I then took it for a spin to Home Depot (about a mile) and it looked fine. Until I got to the HD parking lot. Monster cloud! Parked it for about 2hours waiting for a tow and finally got mad and drove it home. No cloud but smoky.
The point I'm trying to make is that it comes and goes. But when it is smoking, there is no way in hell that I could safely drive it.

Any ideas?

Your mechanic obviously knows nothing about diesels. On a diesel vacuum is created by a pump, not the engine. In a gas engine, a leaking modulator diaphragm can cause smoke because it is sucked in with the intake air.

Is the engine using any oil? Is fuel economy as it has been? If injectors get nasty and no longer make a nice, fine spray they will cause smoking.

Good luck,

It doesn't seem to be using oil and the fuel economy is the same. What would cause it to smoke (and I mean really smoke) only sometimes? If you were driving behind me, you probably wouldn't be able to see my car. By the way, I thought about you when I was changing my HOT oil this weekend. ;-)

First thing I would do is crawl under and look for oil or fuel leaks that could be dripping on the exhaust. Second thing is to check for coolant leak. Random smoke is usally some kind of leak My .02

Well, it's got it's share of oil leaks. I'll grant you that. But the smoke is coming from the exhaust. I was just out driving around the neighborhood and it's I could get it to smoke a good bit but not like this weekend.

In the past, I've noticed that if I let it idle in the driveway for 15 minutes, it'll smoke like the dickens for a bit when I start to drive it but that'll usually go away after a block or so and that's something I've been living with. I don't seem to be able to duplicate this in the driveway. This is what I did each time it let loose:
Drove through the neighborhood and tried to get it to smoke. It was smoking a pretty good bit.
Got on the main road (45mph) and drove about a mile. I could see smoke in the rear view but it was dissipating in the air. Also behaved kind of sluggish (bear in mind that the tranny mod was diconnected)
Got to a stop light or parking lot and all hell broke loose while I was turning around. Dense cloud of white (to me) smoke that smelled of burning oil that would obscure your vision almost completely if you were behind me. The smoke hung in the air and did not dissipate quickly.
Coolant and oil look like coolant and oil.
It does not appear to be using oil other than by leaking.
My main concern is does this sound like something indicating bad rings or a rebuild? Or is it more along the lines of replacing parts that are more "external" e.g. injectors etc?

Thanks,

Matt

Check your coolant level. Kinda sounds like a head gasket problem. I agree with Larry, I don't think your mechanic knows quite what he is talking about.

Thanks. The coolant level is okay and coolant and oil look like they should. Each without the characteristics of having being mixed with each other.

I agree with Larry as well. I've been reading the forums for a couple of years so I'm familiar with his posts and have learned alot from them. I would've never considered an MB diesel if not for the wealth of info on this site.

It occurs to me that maybe I'm not letting you guys help me. Reading the forums doesn't make me an expert but it may have given me a false sense of knowledge about MB diesel theory. Having said that, would a bad head gasket generate smoke that smells like oil that comes and goes. I'm in the weeds here. ;-)

Just checked my air filter on my way to the turbo shaft. Eeeww!
2/3 black. Doh! Will replace tomorrow. Any other ideas or supporting theories?

Look up the post in the recent past on high oil consumption. That person was spewing vast amounts of smoke because oil was being pushed into the intake manifold because of high pressure in the crankcase (caused by a kink in the breather hose) which pushed oil past the check valve on the oil separator and up into the intake.

Will do. Please note that I have edited my previous post.
Thanks. It's hard to search on "smoke" in the diesel forum! You might as well read everything.

Low performance and lots of blue oil smoke = dead turbo leaking lots of oil into the exhaust from ruined bearings and leaking seals.

Mine didn't blow the blue smoke, but believe me, you NOTICE the lack of power.

Peter

My 240D smoked bad until really warmed up, then I replaced the injectors. It was at about 200K. With the new injectors, a little at startup but no more misquito fogger.

My 74 240 D put out white smoke so bad that I had to stop driving it. One day on impulse I loosened the IP bolts and bumped the IP a touch toward the block, Presto no smoke ,put it back on insurance.............

William Rogers.......

Guys,
I'm not specifically familiar with the '77 300D's, but I'd like suggest something I've not seen here yet.
My 220D started smoking irregularly and it turned out to be a cracked vacuum pump diaphram. Oil would go up a line into the intake manifold. There may not be an equivalent situation on the 300D with a turbo and it's positive pressure, but this situation threw me for a while as the pump was working well enough for me not to notice a vacuum problem. It did show up as oil consumption.
John

'87 300SDL
'91 560SEC
'47 Dodge WD-21 Pickup
'68 Mustang Fastback
'69 Pontiac Firebird
'78 Dodge D200 Pickup
'72 crappy boat

You won't get excessive oil consumption from the vac pump on an 83, they vent directly to the chain case and not the intake, and have a piston type pump anyway.

You should also check the oil separator -- if the foot valve is bad, all the oil from the blowby is going down the intake instead of back into the pan. this will be worse after a hard run, and will vanish upon sitting as the oild works it's way into the pan.

Peter

Anyway to test this valve...
 

I thought about that the other day and then was trying to figure out how to test it? Is there a spec as to how much vacuum/pressure it should hold? I thought about maybe rigging the mity vac to test it. I did blow through the line just fine and then tried sucking a little on it and it seemed to close okay but I didn't really want to put too much vacuum on it with my mouth...

I'm beginning to think that maybe I did not blow my turbo but rather that my blowby is bad enough to warrant concern that it is back pressuring the crankcase. I came to this conclusion after running the 84 with the breather off the valve cover and man it has hardly any blowby at all. The 81 on the other hand has a good puff, puff going on at idle and blows pretty good at mid throttle. It also blows enough oil on hard run that it dripped three or four drops after stopping for a few minutes after the run. I know this is a dead horse but how in the earth can you tell if you have too much blowby?

Stand behind it while it's smoking if it's white smoke it should have a distinct deisel odor. that means incomplete combustion ,bad rings? IP timing,
or chain strecth can cause it , I always start with the simple one first which would be IP timing , bumping It worked for me, of course the drip method is the correct method to do IP timing..........

William Rogers...........

I replaced my injectors, and the engine is still smoking...
 

My case is a little different becuase I ran my Oil Low due to a pinched breather Hose.
My Car at 300K miles was fine until then though it had other issues causing poor performance. Now I have a lot of the performance issues solved, but I got smoke which I never had before running the oil low.
I am in the middle of a series of tests to solve the smoke. It may be quite simply worn rings. I DID GET NEW INJECTORS. My compression after the oil loss was 330 to 360, and my oil pressure at idle is 1.8 bars

I DO NOTICE this. When the engine is cold, the car starts off like a 2,000,000 ton Cargo ship. When its warm I can literally feel things to Pep up.

I NEED HELP TOO

Checked the timing..
 

I am not being a wise guy, but I wonder how the timing can be ever that messed up.

If you advance it too much, you cant make your fuel pump linkages work and get full play.

And if you retard it too much, your piping wont fit back on no matter how much you try.

Also there are starting issues and vibration that you will notice anyway.

Here's the story ,my 74 240 D 'Pearl' (my first Mercedes) defines the term "been around the block"
and had survived several teen age drivers before I got her.

Pearl smoked a bit when I bought her but being new to diesels I did not worry about it till after many miles and years of driving the white smoke got to the point where it became undriveable . I parked it and bought an 81 SD "Goldie aka Belle"

One day a mechanic friend stopped by and I started Pearl to show him the smoke , we talked about the diesel odor of the smoke then decided to bump the pump toward the the engine just to see what would happen .We could not get the bottom bolt loose so we loosened the other two and with a heavy hammer and a piece of heavy square stock we bumped the IP (lines attached) toward the engine block a small inkerment at a time the smoke lessened with each bump and the enginer smoothed out till there was no more smoke than my non smoking SD I put Pearl back on insurance and drive her mainly on the back roads where we live...........


William Rogers........

Injection timing is fairly important. It will be late due to timing chain wear and some pump wear, also the timer can wear too.

Worst case someone has set it with the engine in dubious condition without replacing the chain, or with the timer stuck, so that it is way off when everything else is OK.

If there is evidence the pump has been pulled and replaced, it could have bein installed improperly, too, and that is a real crapshoot.

A diesel can actually run with the timing almost 180 degrees out if you have enough fuel vapor in the cumbustion chamber when the heat is high enough, but it will smoke terribly.

Best to check.

Excessive blowby is when you get large puffs like a locomotive at idle. Usually a result of worn out or stuck rings. Occasionally, resetting the timing correctly and changing to synthetic oil will free the rings and restore compression, but usually the cylinder walls are worn out and it needs rebuilding.

Worn out injectors will cause trouble, too.

Peter

I'm getting quite an education. Thanks folks. Will keep you posted.

Well... Here's the deal.

I have monstrous blowby. Not so bad at first, but when she gets hot, the valve cover tube chugs like a locomotive. (psfred is the winner of the mink beer koozie) The mechanic thinks that we may have a chance at salvation by changing the injectors (done) and keeping the rpm's up when I'm driving to free up ring gunk. We disconnected the breather tube from the air filter. Runs like a gasser. Very little smoke.

Troubleshooting went something like this:

1. Drive car in default configuration. Oil smoke. Could not duplicate my mosquito fogger symptom.

2. Check for puffing at valve cover. A bit excessive.

3. Run the hell out of it. Puffing like hell and doggie. (poor acceleration).

4. Remove breather tube and run the hell out of it. Smoother and with much less smoke.

5. Replaced injectors and checked that loosening the fuel lines on each injector made a difference with the idle. Based on this test, there are no "dead holes".

6. Run the hell out of it. This thing comes close to hauling ass.

7. My instructions are to keep the RPM's up and check the oil level. It's not using any so far. Not leaking as much either. This is with the breather tube disconnected.

8. If this doesn't work, lower end trouble. He says he's snatched a few from the brink of death by using this program. He seems to have a genuine love for these cars and a knowledge of their history. He even made a house call in "The Worlds Fastest 240D".
It had a 6 cylinder twin cam shoe horned in it. But was still badged as a 240D.

Thanks for all your help. Sorry I took so long for the follow up. Replies are always welcome.

Matt

OPEN THEM UP--its good advice
 

I recently bought a 1987 300D. For a while I thought the turbo was dead, I mean this is supposed to be one powerful car, its a 6 cylinder Turbo that should do 100 easy...

Thsi morning I opened it up WIDE OPEN ...smoke came out of the tail like crazy, then suddenly the car accelerated like crazy!!! and the smoke cleared up....now the car really cruises

It was previous;y driven by a housewife...