Hi,

I've been lurking this forum and found it to be a great source of info. My problem I'm trying to solve currently is smoking on a 300TD I bought a month ago with 167,000mi on its odometer (who knows what it really is?). The cluster has a nice gash in it where somebody obviously tried to pry it out of the dash with a screwdriver!

Somehow I didn't notice the smoking as I idled the car and walked around it. Yup, I got mesmerized by the car's beauty. It seems to come and go and there is less after hard driving which I did during the test drive. But if it is allowed to idle it comes back. Not terrible James Bond screens but enough to be embarrasing at red lights. Smoke is dirty gray in color. Really obvious in some lighting conditions, and not in others. Not the classic black soot nor the whispy white. Just gray and at idle.

I bought the "why does my diesel smoke book" from Mercedes Source.com and it had some useful suggestions. He has the easy and likely stuff listed first. It is a pretty good pamphlet for $13 (incl shipping).

1) I changed a thermostat because it was cold blooded.(still smoked)
2) I burned out the 1 year old fuel.(helped but still smoked)
3) I readjusted the valves, 3 were tight. (still smoked)
4) checked ip timing, was 8 deg BTDC, I reset it to 24 and it ran like $%#@. I set it back to 15 and it ran better. (still smoked)
5) that night it hit me, why was the timing so far out???!!! checked cam timing marks and they were on - within the resolution of the knotch...I know, I didn't indicate it but it is within 10 deg. (still a mystery, still smokes)
6) tried some Diesel Kleen. This helped but it smoked after I refueled. It may have liked the cetane boost. I was too cheap to buy the Lubro Moly from Mercedes Source. I mean, I kinda wondered because they sell a solution for everything short of new pistons and sleeves. Like a filter kit to stop smoking? For real? I've clogged many a filter but never did it make my diesel smoke. Maybe I was wrong...read on.
7) tried road drafting the severe blow-by (still smoked) -- as you can see I'm getting desperate.

I bit the bullet and bought the diesel compression tester at Harbor Freight for $129.99. I gots to know as they said in Dirty Harry.

Here are the compression results:
#1 220psi, #2 310psi, #3 315 psi, #4 370psi, #5 330 psi.

Not looking too good on #1 but I read here the mbz spec is minimum 218 psi, does anyone know if that means min=will not fire?

Also, I recall reading a piece on MBZ.org about 350SDLs bending rod #1 and scuffing sleeve #1, any thoughts why it was #1?

The real eyeopener was all the guck on the injector tips. All the cylinders had this. It was really fouled with a black and greasey foul. I mean one of the tests in the "smoking book" was to run your finger over the injector tip, heck, I cannot even feel the nib of the tip because there is so much goo on it. I can barely see the periphery where the fuel should come out.

Well, wish me luck, I'm going to take the injectors apart and dump the nozzels in the ultrasonic cleaner and reinstall them. I may have to set my IP timing back to 24 BTDC.

Cheers,
Yoko
79 300TD (old smokey)
82 240D (the evangelist)

obviously 220 is too low. did you try it more than once? did you try squirting oil into the cyl? this may be the source of your smoking. perhaps a stuck ring. using good oil and changing it often may possibley free up a stuck ring. lucas oil treatmen is supposed to work for this if a ring is stuck.

the 370 is too high. may be carbon build up.

using qulait y fuel and cleaners and the lucas oil treat may work it out eventually. the only other solution is a tear down and rebuild.

if the compression readings are correct, the engine probably doesnt idle smoothly. my uncle the automotive engineer always said "if a diesel idles smoothly it probably is a good motor".

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I wouldn' THINK that you should have such low compression with such low mileage. Of course someone could have switched odometers but let's say for now it is accurate. You did set your valves correctly as those will play a role in compression readings? I don't know a whole lot about the 617 engine but this doesn't seem right for such a low mileage example.

Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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Compresion adn leakdown test by someone who really knows how to do it will tell you if its valve job time or not.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Yoko,
Welcome to my world. I have white smoke though. My daughter was lighting smoke bombs last night for 4th of July, and yes, I went and started up "The Smoker". My mother-in-law got quite a kick out of that....
I have even compression, and have done too many things to list. Hope your luck is better than mine has been. If Randy doesn't fix Passion Flower soon so I'll have an idea what's wrong with mine, it may be destined for ebay. A nice project for someone, and a monetary blood-bath for me.
Keep us posted.

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

I thought the low 400's were the optimal readings???

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

The 'flower is on the back burner for the near-term; I have a new diesel-powered, German money pit in the fleet:

Attached Thumbnails

 

__________________
Never a dull moment at Berry Hill Farm.

German?? Green and yellow?
A front end loader AND a box blade?! That is cruel.
Country living is starting to suit you.
Your metal collection has a long way to go, though....

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Hi,

Thanks for the tips. I did set the valve lash. Checked it 2x and it looks good.

I took 2 sets of compression readings, 8-10 crank rotations each just to make sure I didn't blow it on seating the compression test fitting or things moved around. Good point about fluid in the cylinder. On #1, I didn't spray anything in. Some fuel leaked in from the injector line. But this didn't make a difference.

220 sounds extremely low I agree, I'm just in hopeful mode right now. I tore my injectors down and ultrasonically cleaned the nozzels and pintles. I'm going to head out to the dealer and get some heat shields and put it all back together and give it a go.

So, it is pretty obvious that the smoke may be the low #1. Bummer.

I will keep posting my results. I still have my fingers crossed on the gooey gummy injectors having something to do with the smoke. That deposit was hard to clean off. It was really stubborn. I'm thinking if it is on my pistons/ring lands I'm in big trouble.

Reminds me of a car my dad gave me. 79 Civic CVCC that had been smoking so dad put STP oil treatment in it. By the time I got it and rebuilt it the rings were gucked into the landings with STP no doubt. When I checked the bores they were still in spec but the STP job thrashed the engine to the point where it needed to be rebuilt.

Cheers,
Yoko

What's the history on this car? Do you know if it was ever run on alternate fuels? Also, are you dissassembling the injectors to clean them?

__________________
Never a dull moment at Berry Hill Farm.

Hi R Leo,

I bought the car from an indy in Mountain View CA. He said he needed to clear some cars from his lot. It was his around town car. Interesting you asked, because here is where things get funny. The car belonged to him in the 80s, a customer liked the car, bought it from him. Drove it till 2003, died, then his wife sold it back to the shop. The mechanic never registered it, just drove it till the reg expired then parked it a year. His landlord apparently complained about all the cars on the lot (he had a lot) and then I came along with my $1800. So the story goes.

Some aspects of the car were very well maintained when I inspected it. After having tons of problems with balljoints and axels on my 240D, I examined the 300TDs and it had perfect suspension parts - obviously replaced. I got so excited I bought it. The smoking was probably sporadic and I missed it. It was running diesel when I got it. All the hoses were stocker hoses so I don't think it was ever a veggie car. Fuel was pretty clear...but could he have run the dog on waste motor oil from his shop? Dunno. As I said, the car had a funny oil filter system - apparently put in to get around using Mann filters.

Oh yes, and I cleaned the injectors by taking them apart. Under all the goo, they had a mirror like finish and all the material seemed to be there. I put them back together (kept all parts with each indvidual injector and cylinder consistent), adjusted the IP to 24 BTDC and it still smokes. The car does run better.

I had planned to convert the car to WVO like I did to my 240D. Haven't gotten to it yet. My 240 doesn't smoke a bit on WVO but it may have good compression. The 300TD has that marginal cylinder #1 and I'm afraid that is it...low compression on #1 not giving me enough combustion temperature for long enough in the cycle.

Bummer! Next oil change I'll try one of these off the shelf engine flush systems. I don't know how many bum engines (gasser) I've taken apart that had low compression with rings glued to the pistons. If this is it, I'm game to take the head off the car and hit it with the bore gauge just to see how bad the sleeve is. (give me an excuse to get a bore gauge with a 0.0001" readout).

Any other suggestions?

Thank you,
Yoko Kobayashi

When you took your injectors apart and cleaned them.... did you put any new parts on when you put them back in ?

Would valve seals be out of the question? From what you described .....
"The real eyeopener was all the guck on the injector tips. All the cylinders had this. It was really fouled with a black and greasey foul. I mean one of the tests in the "smoking book" was to run your finger over the injector tip, heck, I cannot even feel the nib of the tip because there is so much goo on it. I can barely see the periphery where the fuel should come out."
Sounds like a fish fry oil experiment gone bad!!

__________________
2003 SLK 230 (85000)
1999 E300 Turbo Diesel (388,000)
1991 350SD Turbo Diesel (185,000)

Hi,

I only cleaned the injectors. They looked new under all the goo. No pitting, shiny finish. Of course, I'm assuming a lot here, the springs could have been tired or the spray pattern could be messed up.

Still smokes.

Yep, can be leaky guides/valves. I don't have a leakdown kit. Does anyone know if valve seals will cause smoke at idle? I thought this happened when you nail the gas. Maybe my valve seals are totally zorched?

I guess it is next on the list. They don't look too hard to change. I can snap some new stem seals on.

But...I'm really thinking it is that low #1. I just checked the new online mbz manuals and it looks like the 218 psi number is dead minimum, normal is over 300. So that is looking abnormal and a good cadidate for smoke production.

I'm trying to be hopeful, but the problem is staring me right in the face.


Cheers,
Yoko

You said you checked your timing by looking at the mark on the cam... that is not the most accurate method... and the FSM is very clear that " if there are performance complaints" that the method for checking chain elongation ( which affects your valve timing ) must be checked by using the 2mm movement of the number one intake valve...
The valve timing and IP timing both must happen within certain parameters with relation to the position of the crank ( which determines the piston and compression situation at the time of injection )...for things to be right....
Also, have you thought about checking the condition of the Precombustion chamber pintle and holes ? They are very important with relation to proper combustion of the fuel.

yes, those valve stem seals can allow that...

while that is low on the compression.... it is even more troubling that it is so far off from the others... I think MB wants them to be within 10 percent of each other...... and that is actually more important ( down to a point ) than the actual measurements...

"the problem is staring me right in the face."
I HATE when that happens.....