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?

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Matt Camara
'83 300SD
'85 Celica
'98 Harley Springer Softail

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. ;-)

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Matt Camara
'83 300SD
'85 Celica
'98 Harley Springer Softail

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

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Ricali

03 C240 4matic wagon
95 300E 234,000
7 prior 240;s 5 still going
81 300sd gone
65 230sl gone
49 Studebaker Champion
90BMW convert.167,000
60 Dodge D-100

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

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Matt Camara
'83 300SD
'85 Celica
'98 Harley Springer Softail

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.

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

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?

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Matt Camara
'83 300SD
'85 Celica
'98 Harley Springer Softail

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.

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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

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.

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Matt Camara
'83 300SD
'85 Celica
'98 Harley Springer Softail

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

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

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.

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79 240D (no name yet) 203K Miles Maple Yellow
98 2500 4x4 HD Dodge 24 Valve Cummins TD
83 Chevy Van (Dead-Trans. shot)

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

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

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?

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique