My '84 300D has recently begun to smoke... 'seems like just as the turbo kicks in. This car has just turned 78K miles, has lots of power and typically idles fine. Lots of clues here, but I can't seem to put them together.

First, it seems to have what I believe is a vacuum leak that becomes audible just before 2.4K rpm. I've settled on this being a vacuum leak as, if I punch on the heater or AC, the high pitched sound goes away until the movement of the mixing door stops... it then returns. Under load, there is no vacuum leak type sound... it's only as load is just letting up that you can hear it. It can't be heard unless the car is moving and at that 2.4K rpm range. I've climbed above and below the car numerous times and applied a smoke machine to the vacuum system and cannot find a leak.

Secondly, there is a slight bit of oil on top of the valve cover near the fill cap. It looks like there is excessive pressure possibly forcing oil out (perhaps this is where my whistling is coming from?) I've also noticed a couple of drops of oil on the floor after running to town and back (~60 miles) then parking the car over night. It's very difficult to tell where the source of the leak is at this point. The oil leak is minor and there is no noticeable drop on the level on the dipstick.

A third clue is that the car runs very well and has lots of power, however, when I get to a stoplight after having run the 30 miles into town, it runs a bit rough at idle... not horribly so, but enough to make the car shake ever so slightly. Upon returning home and, unloading groceries, the car idles fine for about 5 minutes, then starts to idle a bit rough. I did the last valve adjustment ~ 8K miles ago and all seemed fine... the smoking (and other symptoms) just started in the past 300 miles or so.

Air filter looks fine, Diesel Purge didn't seem to help. Again, the car has a lot of power and accelerates and runs well... as long as I don't look in my mirror as I attempt acceleration.

I thought about injector issues, but does that explain the oil issue? I'm completely stumped on this and am toying with replacing the injectors (cheaper than having them tested!) but wanted to field this before throwing parts at it.

Any ideas would be welcomed!

Thanks!

-l-

__________________
'84 300d turbodiesel (83K miles)
'96 300d (226K miles)
------------------------------------------------
other fine diesels...
'99 Polaris diesel (Fuji Heavy Industries single)
'01 Diesel Trail gator (Yanmar triple)
'95 John Deere 970 (Yanmar quad)
'11 BMW 335d
'12 VW Jetta TDI

****************************************
'00 BMW K1200LT
'02 BMW R1150RS

'15 BMW R1200GSA

Step one for me is to determine whether it's oil in the exhaust or unburned fuel. Is the ALDA installed and intact?

I don't think vacuum is a related issue. The vacuum system is separate from the air intake and charge system. You might be hearing the turbo whining louder than usual under load suggesting worn bearings, but that can't be associated with ACC settings.

How oily is the hose between the turbo outlet to the intake manifold and wastegate actuator? Have you checked in the past as a point of reference?

Sixto
83 300SD

Its possible, there is an vacuum leak and if the egr is still connected....That the egr isn't opening/closing and thus not enough fresh air is getting into the intake....causing smoke...

What color is it?

I believe the smoke and oily valve cover are two different issues...

Low mileage examples, can suffer more wear then a high mileage example....from sitting to long, just going from home to grocery store etc...

There can very well be a large build up of carbon, that needs to be burnt out...with some high speed driving aka Italian tuneup(drive it like you stole it)...

Chances are, you do need injectors...at that mileage I doubt they've ever been changed, injectors that are peeing instead of spraying can cause a host of problems....from melting a piston to excess carbon build up...

__________________

I think your symptoms are screaming turbo / ALDA

Check the line running from the turbo to the ALDA (box on top of the IP on the other side of the engine) for cleanliness / oil and leaks.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Two or three different problems, I think.

Smoke: I'd start with injectors, get a set from Greazzer (forum member), or buy Bosch rebuilts and send them to him for test/adjust of pressures.

Oil: Welcome to the club! You'll need to clean off the entire engine, and then carefully observe where the oil is leaking from. Could be as simple as the o-ring under the injection pump shut off lever or as complex as the oil pan gasket. May be multiple places, just need to dig in and figure it out or pay a mechanic to diagnose and then decide if you want to do the work or pay them.

Noise: I agree with a leak in the intake or exhaust, nothing to do with vacuum. You can confirm by plugging the vacuum lines to everything except the brakes, and then going for a drive. Transmission will shift REALLY firmly, but a short test drive won't do any long term damage.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Another possibility not yet mentioned is valve stem seals.

As stated by others, you likely have more than one issue going on here due to the age and low miles.

Dkr.

Thanks all for the replies. In order...
Sixto/Stretch: The ALDA is indeed there. I pulled the bajo bolt, all is clean and there seem to be no leaks there nor anywhere on the pump. Though it may not be related, I'm certain there is a vacuum leak as the sound I'm hearing stops for ~ 2-3 seconds whenever I actuate anything vacuum related, i.e. mixing doors, door locks and such. The pitch does not vary either... just like someone is blowing a high note on a penny whistle.
Cooljjay: The smoke is black and only noticeable occurs just as the turbo kicks in. 'Tried driving it like the BMW... still smokes. The odd thing is it runs absolutely fabulous!

MaxBumpo: I'm thinking it may be the injectors but I don't know enough about that. 'Raises a question... can't a person just buy new injectors and have them be at spec pressure/pattern?

DKR: sounds like a nightmare... I'm hoping for something that will be a bit less intrusive to fix!

Oil source... it seems (as near as I can tell) having dug into it, that the bulk of the oil leak is coming from the breather on top of the valve cover. After pulling the air filter housing and crawling around, it seems that is the main source of the leakage. I had no idea it was putting out that much oil, but sure looks like the culprit.

Thank you all for your time on this. I intend to dig deeper come this weekend (unfortunately I'm still working for "the man" and don't have a lot of time during the week.) The moral support really helps!

-l-

__________________
'84 300d turbodiesel (83K miles)
'96 300d (226K miles)
------------------------------------------------
other fine diesels...
'99 Polaris diesel (Fuji Heavy Industries single)
'01 Diesel Trail gator (Yanmar triple)
'95 John Deere 970 (Yanmar quad)
'11 BMW 335d
'12 VW Jetta TDI

****************************************
'00 BMW K1200LT
'02 BMW R1150RS

'15 BMW R1200GSA

I would personally separate out these issues:

- Vacuum leaks are extremely common on these cars due to the age and the vacuum lines and associated parts getting brittle. I don't see that as related to any of your other problems. You need to get a vacuum pump on each of the lines, usually to first isolate whether the problem is under the hood or in the cabin and if is is in the cabin, then to isolate each line to figure out which vacuum actuator it is. If it is inside, it is most likely a vacuum actuator on one of the doors.

- The oil leaks are pretty common and require a bit of work to deal with. Some people let the minor ones go for a long time and it isn't a problem as long as you keep enough oil in the crankcase. I always check mine when I fill up for fuel. When you diagnose it, there's tons of info here on what to do for each one.

- The injectors are most likely the cause of shaking at idle. Some shaking is normal as it is a diesel, but most likely you have fuel carbon build-ups inside the injectors and they need to be either cleaned or rebuilt with new nozzles. Diesel purge may help as may an Italian tune-up, but often the injectors just need to be pulled out and cleaned. I believe the maintenance interval is every 100,000 miles but it may be sooner for you due to the number of years and it may be more of an issue if the car has been sitting for a long period of time. I've started adding WalMart 2-stroke oil (1 oz per fuel fillup) and it has helped with idle shaking -- gone from minimal to rarely ever noticeable. Mach4 has a thread on it here somewhere.

- For the smoking, if it is the valve stem seals you will notice it getting rapidly worse over time to the point where it is smoking at idle and then pretty much all the time. I don't believe the issue is mechanically catastrophic, but you will get tired of it pretty quickly.

Dkr.

Here's your test: disconnect and plug the various vacuum consumers, see if you can determine which vacuum circuit is the source of your noise.

No - the Bosch factory spec is a 10 Bar pressure range, but Mercedes specifies a 5 Bar pressure range, so you need to have your injector set "balanced" so the opening pressures fall within a 5 Bar range. The last time I purchased a set of rebuilt Bosch injectors, I took them to a local independent garage to have the pressures checked, and fortunately they all fell within a 5 bar range so no adjustment was necessary.

You may want to replace that breather hose with a new one-piece hose and see if that seals up the leaking. If your engine has excessive blow-by due to carbon coked rings, you may be able to clear that up with a Marvel Mystery Oil treatment (fast) or by switching to Mobil 1 synthetic oil (slow).

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

(Warning I did not spell check.)
There is only a limited number of Vacuum Lines going through the Fire Wall.
The Black one is a vent and simply goes iniside and connects to nothing.
There is a Brown with Blue Stripe and Brown line that are poart of your Vacuum shut off setup.

All of the other Vacuum Lines can be disconnected and the supply sides plugged off.

If you sound is still there after that then it is not likely it is a sound from the Vacuum. I gues to be sure you could move on to disconnecting the Brown with Blue Stripe and Brown just to make sure the sound is not coming from the Shutoff Valve on the Steering Colum Lock.

You can disconnect the Vacuum Line at the EGR and plug the vacuum supply side off. That should keep the EGR from openig.
The test for the EGR itself should be similar to a Car EGR Test of the same year. You disconnect the Vacuum Hose at the EGR and hook up a Mighty Vac or other vacuum sourse to the EGR. As you pump on the Mighty Vac and the vacuum rises the EGR should open and your engine should start runing rough when the EGR opens.

You might try disconnecting the ALDA Line and plugging of the Boost side and go for aride and see if it still smokes black.

You never said if your exhaust smells like burned Oil or simply normal.

If the Turbo Charger is leaking Oil especially on the Exhaust side it will blow black smoke. If you disconnect the Exhaust end near the Turbocharger and look inside if you see a lot of shiny wet looking carbon Oil is coming from some where and getting into the Turbo Exhaust end.

That does not entirely rule out the Oil coming from the Engine. You can see that by removing the Exhaust Manifold and looking into the Exhaust ports of the head. If Oil is coming out of their you will see that shiny carbon.

You can also pull an Injector and look down inside the prechamber. If the carbon in the prechamber is shiny and wet looking you are burning Oil. When the Injector is out you ca look at the base of the Injector Nozzle were the pinte/needle sticks out and see if the metal around it is all burned or erroded away.

The Compressor side of the Turbo Charger can also leak Oil and throw that Oil up into the Intake. If that is the case right after you start smoking black you would expect that if you took a peak in the Intake Maifold there would be Oil. Especially in the area closest to the Turbo. And, you would also expect to see the results of Oil in the precombustion Chambers if the Cylinders closest to the Turbo. That shiny carbon I have spoken of.

You did not say if your crankcase Oil level is falling.

Your Injectors would have to be incredably bad to blow black smoke. I think if it was the Injectors your idle would be worse. Mine had 198K on what looked like the original Injectors the Nozzles of which were in bad shape.

You did not say you were using only Diesel Fuel or if the previous owner had used only diesel fuel.

Of course your Air Filter and Air Inlet need to have no restriction.

I suppose if enough Oil is gettin up into the Air Filter Housing (not the CA Air Filter Housing) from the Blow-by that could also cause balck smoke but you can discnnect that breather tube and go for a drive and see if you still have black smoke. If with the tube disconnected you no black smoke you know it is the Blow-by causing the issue.

__________________
84 300D, 82 Volvo 244Gl Diesel

Well, I've finally had some time to devote to this project and appreciate all your help on this. I think it may be a bit of a drawn out process to attend to the vacuum leak as I can only hear it when the car is moving. I've tried attaching a vacuum pump to the system, thinking that maybe I would be able to hear it at idle, but no luck on that.

I should mention that when I bought this car, it had a Greasecar conversion on it. I think that the previous owner neglected to switch over to diesel before shutting off the car at least once and got solidified crud in the fuel system. I believe that's why I got the car for such a good price... it made the car run lousy. I pulled off the conversion kit, cleaned out the fuel system and the tank, etc.. It took a good 1000 miles to get the car running correctly and all the crud out. As I mentioned earlier, the car runs extremely well now with lots of power and the smoking issue just became apparent recently. I drive the car at least once/week to town (~60 miles) just to keep it from sitting and, again, it's been running very strong... much stronger than my E300. Sometimes it takes me by surprise how the car takes off when the turbo kicks in... it has much more power than I would suspect out of this car.

I run Rotella 5-40 full synthetic in all my diesels (other than the 335d) and have noticed no drop in level on the dipstick.

I found a very good price on a new set of injectors, so during my winter break, will pull the injectors and see what I can see on the old ones and inspect the prechamber. The exhaust does not smell of oil by the way... just diesel as far as I can tell.

THanks again!

-l-

__________________
'84 300d turbodiesel (83K miles)
'96 300d (226K miles)
------------------------------------------------
other fine diesels...
'99 Polaris diesel (Fuji Heavy Industries single)
'01 Diesel Trail gator (Yanmar triple)
'95 John Deere 970 (Yanmar quad)
'11 BMW 335d
'12 VW Jetta TDI

****************************************
'00 BMW K1200LT
'02 BMW R1150RS

'15 BMW R1200GSA

First of all, I apologize for not having specific 123 info for this. It's been ten years since my 123 left the barn, I have no manuals, and memory is starting to fade.

However, I can tell you that there are a only few ways that this happens. The first is that you have a partially blocked exhaust pipe. This can sometimes be fixed by taking it on the road and doing a stretch at high RPM. This is especially true if your car has a DPF, which only regenerates at high temperatures.

A more common problem is an air leak in the engine itself, usually the valve cover or the oil pan. What happens is that when the turbo is engaged, it can draw air through the valve train and crankcase. If everything is sealed up, the only thing that will pass through the vent tube are blowby gasses. But if you have a leak: a bad valve cover seal, oil filler cap seal, breather grommet, oil pan gasket, dip stick o-ring, main seals, etc, then oil-soaked air can be drawn right through the engine and into the air cleaner or turbo. Every Mercedes engine has some sort of oil separator and PCV valve, and while I can't show you what a 123 breather looks like, I've done a little writeup on the 602 which may give you some ideas:

Mercedes Valve Cover Breather

The 603/603 is a particularly poor design, because the only way to service the PCV is by replacing the valve cover. I'm not sure that's true of any other engines.

If your vacuum pump vents into the timing case, then a leak could also explain the noise, as the entire internal engine space is interconnected. So what you want to look for is any evidence that the engine envelope has been compromised.

Well... I hadn't planned on dealing with this today... just a few spare minutes on my hands, so I pulled the injectors. There is some oil on the seat of the injector hole nearest the front of the engine... the others have no oil in them... just, what I would consider, normal gunk. The injectors have some carbon on them but don't look horrible. It does look like the fill cap is leaking a bit... 'not sure, it could be coming from the breather. I also noticed a small bit of oil on the front barrel/intake of the turbo.

Another oddity is that the injector nearest the firewall is not original... stamped that it's rebuild to specs. I find that odd as the car only had ~ 50K miles when I got it...

curiouser, etc...

I am a bit worried about the oil in the seat of that first cylinder...

Back down to investigate...

Thanks!

-l-

__________________
'84 300d turbodiesel (83K miles)
'96 300d (226K miles)
------------------------------------------------
other fine diesels...
'99 Polaris diesel (Fuji Heavy Industries single)
'01 Diesel Trail gator (Yanmar triple)
'95 John Deere 970 (Yanmar quad)
'11 BMW 335d
'12 VW Jetta TDI

****************************************
'00 BMW K1200LT
'02 BMW R1150RS

'15 BMW R1200GSA

Describe the condition of the front drivers seat. Worn side bolster etc. Seat pretty much like new or whatever.

I might start with a compression check of that number one cylinder. Also turn the engine over with that injector removed. Any oil spraying out? Even idle the engine with the injector out and a safety face shield.

The number one injector could also have a broken spring or be seriously cruded up so it does not close properly. I might grab a used injector just to use as a test aid. Or have someone test the existing one.. A simple repositioning of two injectors is not adequate for your issue.

I am trying to suggest that whatever the odometer reading is on these cars is not to be taken too seriously. You got the car with 50K claimed miles. The chances are small that anyone driving that little would have invested in a vegetable oil system. Fifty K miles was only a 1500 mile per year average or so.

Anything is possible though but to judge a 123 cars overall milage the condition of the front seat is useful sometimes. Also in general you finding a rebuilt injector in the last cylinder is very uncommon in a low miles car. At your milage the steering wheels indicated appearance should also be like new.

To research what a new steering wheel looks like check the archives or post a picture of yours for members to evaluate. Also a picture of the driver side bolster of the seat by the door. A car with 80K miles now is different to consider service wise than one with about the normal expected miles. Of the four 123 cars I have I would not bet anything that any of them are an accurate indication of the odometers claim. Well maybe one and a slight chance of another one. Nothing I would bet on though. There are more reasons for the odometer readings to be inaccurate on the 123 diesel cars than any other car I can think of. It just makes it somewhat easier to have some known indication of total miles to determine what is probably wrong.

I was mentally leaning towards turbo seals until you described the first cylinder. Your description of issues and observations is better than some incidentally. This can really help at times.

Thanks for the thoughts Barry... will attend to some testing, perhaps next weekend as time permits.

The interior of the car is consistent with the odometer reading... i.e. the steering wheel/dash/seats/carpet/etc., look close to new. The car belonged to a 93 yr. old woman who, once passed, willed the car to her son (35K miles on it at that point.) They didn't know what exactly to do with it and being "progressive" and from So. California decided it would be "cool" to run it on used veggie oils. They put the Greasecar kit on at 40K miles (criminal, eh?!) and said that the car never was the same afterward. I pulled out the conversion kit when I bought the car and sold it for $1K. While crawling under the car noticed that it was incredibly clean, no rust, pretty much spotless so again, I do believe the odometer reading is correct.

Back to your statements... do you believe a bad injector might allow oil into the one cylinder? That would be awesome if that were the case.

Thanks much for the reply,

-l-

__________________
'84 300d turbodiesel (83K miles)
'96 300d (226K miles)
------------------------------------------------
other fine diesels...
'99 Polaris diesel (Fuji Heavy Industries single)
'01 Diesel Trail gator (Yanmar triple)
'95 John Deere 970 (Yanmar quad)
'11 BMW 335d
'12 VW Jetta TDI

****************************************
'00 BMW K1200LT
'02 BMW R1150RS

'15 BMW R1200GSA