I had posted this on another forum with no response, a friend suggested I retry it here as a last ditch effort.

1987 300 SDL, 250k on the odometer, good old car, looks like crap (paint is shot) but ran well, was my wife's daily driver until last Feb, it started to miss or drop a cylinder at idle, when this happened it would then emit large volumes of blue smoke from the tail pipe that smelled like unburned fuel. Upon acceleration, just above idle it acted like a switch was flipped almost, as it would smooth out and the smoke was gone. It would run all day like a dream at highway speeds. Around town it was a PITA because of the miss/hesitation and people flipping us off for killing the planet with the huge clouds of smoke. We bought her a different vehicle.
I began to research, and finally decided it had blown the oil passage at the front of the #1 cylinder and was dumping engine oil into the #1 cylinder. I read that a tell tale sign was to remove #1 injector and see if the prechamber was full of oil. It was, so I figured that I had surely found the cause.
The car sat most of the summer, I finally tore into it last month, but after pulling the old head gasket I could not see where it was blown. The #14 head was delivered to a machine shop, they checked it for warpage, and cracks, there was none. I re assembled it with a new Victor head gasket and new bolts. Also the intake side of the turbo looked wet with oil so I rebuilt the turbo as well, also new engine mounts and was able to procure a set of injectors out of a 603 engine with only 65k on it, that ran beautifully. The owner was looking for a low fuel economy problem so he ordered new injectors, he let me have his old ones for the core fee. His new injectors didn't make one bit of difference for him either.
Anyhow, got it all back together, and fired it up last Saturday and it's doing the same exact thing, no difference, except maybe a little quieter idle, due to the injectors I think. The timing chain does show about 8 degrees of stretch, I know that is out of spec, but not sure it will cause this problem. I owned a 300d that had a chain so far out it chattered like crazy and it still did not exhibit this problem, this one is quiet with no chatter in the chain. I have not done a compression check because I don't have the proper equipment.

I am at my wits end with the car, it has some other problems too, so my wife wants me to stop spending money on it and call the junkyard and have them come get it. I am almost in agreement with her, but now starting to think it may be something in the injection pump that broke and is causing it to over fuel at idle. I have owned 5 of these OM603 engines over the years and they all run rough upon start up, (some worse than others) then smooth up fairly quickly, this acts like that only a little worse and never smooths up at idle. Is there a temp sensor that richens the mixture when cold then as the engine warms up, it changes the mixture?? Maybe it is always thinking the engine is cold??
I read somewhere it could be an internal spring in the injection pump, that broke but couldn't find much more about it.

If a fairly simple and economical solution cannot be found then the car will be sold for parts/scrap in the very near future.

Any help or ideas, would be greatly appreciated.
Thanks in advance.

You spent all the money, time and effort and you did not do a compression test? This is a MUST. I have similar problem with 1 or 2 cylinders having low compression. I overhauled the engine by removing the top, dropped oil pan and honed the cylinder. Reinstall the rings or new rings if they are worn or broken. I managed to bring the compression from < 100 to > 300 psi with engine cold. This simple overhauled method saved 2 300SDL.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

Yes, I suppose I am an idiot for not doing a compression check, I am a DIY'er so maybe not up to speed as much as I should be with these engines.
I kind of figured with the mileage these engines are known to be good for, and the head gasket and head cracking problems that these cars are known for that the short block/bottom end is fairly bullet proof.

Guess I was wrong, but I'm also probably not willing to open it back up to do a complete overhaul on it. Rest of the car is not worth spending that kind of money on the engine.

1998.5 Dodge Ram/Cummins 375k
1987 300 SDL 252k (broke)
1987 300D-T 73k (beautiful original car, 'Crème Puff')
2013 VW Jetta TDi 6k (Purchased New)
2993 Mustang LX 5.0 convertible (just for fun)

I am a more DIYer than you. I am trained as a software engineer, not a mechanic. I do not like throwing money at old cars. Overhauling the engine is cheaper than you think. Disclaimer: this is what I did and others may have different opinion.

1) Head gasket set about $70
2) Clean the piston grooves and reuse the 2 top rings. I replaced the oil rings, about $12 each including shipping.
3) Hone the cylinder, cheapo honing tool is about $20.
4) Examine the rod bearings. Reuse them if OK.
5) Oil pan gasket, about $15

I would take a chance and reuse the HG you just put in. It should be OK as it has minimum mileage. I did the same with 1 SDL. If the car is worth keeping then spend the sweat labor and overhaul it. It not then just junk it. Good luck with your decision.

btw: A compression tester can be had from Harbor Freight for $30.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

IDK, I would not hone a cylinder and put the old rings back in. I also wouldn't reuse a crushed HG.

If the cylinder has low compression, the rings are tired. Honing the cylinder makes it rough. You'll put 20 years of wear on the old rings if you run them in a honed cylinder.

Head gaskets that aren't metal tend to squish a little and some have a small bead of tacky sealent that is squished and dries in place. I would only reuse a metal HG because they don't deform as easily.

The labor to pull the head is so large that I'd be PISSED if I had to take it off a third time because I reused an old head gasket.

If you do a compression test and find poor results, you'd have to make up your mind on what to do. It'll cost you the gauge and some heat shields.

If you get good compression, you know to look elsewhere.

__________________
'84 190D 2.2 5MT (Red/Palomino) Current car. Love it!
'85 190D 2.2 Auto *Cali* (Blue/Blue) *sold*
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OK, I have overhauled a couple engines in the past mostly Chevy, but a Ford and Chrysler small block also, tinkered with a Jag and did a head gasket on a Volvo once.
I'm not all that smart, but I don't understand what is to be gained from what you are advising? Not trying to be snotty just asking. You say hone the cylinder walls to break the glaze, I get that, but you say reuse the 1 & 2 top rings. Those are the compression rings, all the oil ring does is distribute oil onto the cylinder wall. If my compression is bad then I wouldn't think keeping the top rings is going to solve anything, maybe make it worse since deglazing the cylinder wall is going to make the cylinder ever so slightly larger, the old rings if worn already, will just have a worse time seating and sealing. I understand now that I could have broken a ring which is letting the engine blow oil and lay down at idle, I never really considered that before.
And, the best thing about the car was the engine when it was running good. Now that the engine is not running right, I really do not have much of anything. The car is complete, and has good tires and now a rebuilt turbo, but what I have now are a few good parts and that's about it.

I wish the engine still did run good, might make a fun project to put it a Jeep or something, but I have so many home improvement projects that need done I don't see it ever happening, this is also why my wife is nagging at me to quit messing with the SDL and start doing other things that need done.
Thanks again.

Mechanics also reuse rings. HG is debatable but I reused my newly installed HG again with NO ill effect. The choice is yours and yours alone and that is why I put a disclaimer there. It is your car, your money and you make the best decision with the all the info you have at the time.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

It was a bad injection pump when I had the same problem. My compression was good, newer chain.

__________________

Present
1987 300SDL
1991 300SL
1990 560SEL
2001 ML320

Past
1969 200D 1979-82
1983 300SD 1984-85
1972 250C 1982-02
1995 S350 2011
1997 S320 2012

I wish someone could elaborate on injection pump problems. I did a search and really couldn't find much, apparently they are very reliable as a rule.

After more research I still stick with my original diagnoses. I know, I know, I never performed a compression check. But I had all the symptoms of a blown head gasket at the front oil galley. 1. Noisy lifters-Yep, 2. blue smoke at idle-Yep, 3. Miss at idle that goes away at higher speeds-Yep, 4. increased oil consumption-Yep, 5. Oil leaking toward the front of the engine and coming from between the head and block-Yep. In other words everything pointed towards my inevitable conclusion, no compression check needed.
Also, I have read on other sites that replaceing the head gasket is not always sucessful, one poor fellow claimed he did his 3 times before he could get it to seal. In the end he could never get the #14 head to reseal, after doing the head gasket 2 times he found a #22 head did the whole job the 3rd time and that cured the problem.

As an aside, I was tinkering with it some tonight after work, I turned the little idle knob from 4 to 5 and the idle increased and when it did, most of the blue smoke went away and the miss was much less noticable. I really think my head gasket replacment was unsuccessful.

Now I just have to decide if I'm willing to tear it all apart and do it again, I don't think there is much use unless I install a different head at the same time. since I don't really want to spend any more money on it, I think it will be put up for sale for parts in the very near future.

If anybody is interested in a parts car, you can PM me but better to email at ebrobb69@gmail.com. The car is located 35 miles SE of Des Moines, Iowa.

After being discouraged and irked after having the same symptoms and a seemingly unsucessful head gasket replacment, I decided to do some more tinkering this evening.
When I initially fired the car up after completing the job and the same problem existed I drove the car around the block once to confirm then parked the car and walked away pissed.
Tonight after work I decided to make sure all fluids were topped up and take the car for a highway drive, we live right on the edge of town so I got the car out on a country highway and up to speed. At first the miss and smoke were still there, then the miss went away like it usually did at highway speeds and the smoke subsided. I went about 4 miles or so then turned around for the drive back, and I noticed the miss did not return at idle, nor did the smoke. I was able to return home with slightly less power than I recall but I haven't really driven the car for months.
I pulled in our drive and the car idled good, of not great, but the miss was obviously less severe and there was no smoke. I got out and walked to the rear of the car to make sure I wasn't just dreaming.
It still doesn't idle the greatest but didn't before either, I'm thinking now that the somewhat rocky idle now could be that the timing chain is so far out of spec.
Is it possible that the piston rings on the #1 cylinder were so soaked and loaded with oil from when the original head gasket was leaking that it just took some highway driving to get everything cleaned out? I'm not sure what happened but so far I like it and am more encouraged that my effort was worth it.
I am going to do that same thing tomorrow night and report back, as it was totally dark when I quit this evening.
Oddly the heater began working correctly as well, during my drive this evening I had good even heat, before it would fry you or nothing, maybe the car has decided it is going to the junkyard if it doesn't behave!

Keep us posted.
I am the one who on the other Forum recommend that you post here.
Perhaps Prayer really does help?

I forgot to ask this on the other Forum; is the top of your Fuel Injection Pump dry with no Fuel Leaks?

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84 300D, 82 Volvo 244Gl Diesel

Yes the previous owner had done the delivery seals on the IP and the glow plug replacement with all the necessary reaming involved. He said it was a real PITA.
Now that I had the head off the machine shop hot tanked it and the prechambers looked great when they got done.

If I fire the old girl up tonight and fiddle with it more over the weekend and it doesn't go back to doing the billowing clouds of smoke thing and miss, I may consider doing the timing chain at some point in the near future. I'm sure it would help with the idle and smooth it up quite a bit. But until I put a few more miles on it I think it's too early to tell yet, but I'm hopeful.

And, Yes I believe in prayer. about 1 1/2 years ago I was down in the back with a blown disc and a pinched nerve. I had an MRI done and it clearly showed my herniated disc. My friends at church and my Mom's church began to pray that I would not have to undergo surgery, because we had heard horror stories about people that had had many complications after having back surgery. And I never had to have surgery, my disk healed itself, but my improvement started the day after I was put on the prayer chain. Maybe I should have been praying more over the old 300SDL before now.

Thanks for the help!

Have you checked chain elongation and IP timing? Eyeballing chain elongation is as simple as aligning cam sprocket and cam tower marks and reading off the crank pulley. Average a few readings for confidence. Then center the RIV tang in the inspection port by eye if you don't have an IP locking tool and read off the crank pulley.

You can also loosen injector lines with the engine idling to see if you can isolate the miss to a cylinder. Swap injectors if you find a suspect so you know if its the injector or the cylinder.

Sixto

Yes that is how I determined that the chain was had 8 degrees of slack in it, I lined up the camshaft timing marks, then looked at the crankshaft pointer, I turned it over by hand several times. Sometimes it came up about 6 degrees, and sometimes it came up 10 or even 11 degrees. I kind of averaged it to 8 degrees.
I have never attempted to look at the IP indicator through the port on the injection pump, I was planning on doing more research on this and thought I probably needed some kind of diesel timing device, but I guess I could line up all the marks and then look with the engine not running, see how close it is.
The engine fires immediately when you barely even bump the key, if that means anything, an old mechanic told me once if they start easily then timing is fairly close. Maybe he was nuts.
I loosened each injector line last night one at a time, Seems like the one that made the least difference when loosened was #4, before the head gasket job it was #1.

Thanks, gotta get back to work.

If it starts easily, compression must be good. You might force the issue by trying to start it with the glow relay disabled. All four 603s I've been through are notorious non-starters without glowing, though, despite decent cold compression test results like 350psi or better.

This the RIV tang you want to center in the inspection hole -



The locking tool is a positive method but you can trust your eyes with a mirror or use a (6mm?) soft dowel that just fits the hole and give it a tap. Extract the dowel and see if the indentation is centered.

Swap injector 4 with a neighbor and see if the 'lower contribution' stays at #4 or moves with the injector.

Sixto
87 300D