Timing chain stretch causes the cam timing and injection timing to lag the crankshaft. At first it causes no real noticeable problems, but as the stretch increases, the retardation of timing begins to show up as a reduction in power, white/grey smoke especially at idle, and elevated operating temperature due to the late injection timing. If the chain is REALLY worn out, you can sometimes hear it slapping inside the timing cover. Definitely a situation you want to avoid! If allowed to go long enough and assuming the chain doesn't break first, you'll eventually have the pistons hit the valves with catastrophic results. Not to mention the chewed up sprockets in the timing pathway.

The easiest way to check chain stretch is to pop the valve cover off, line up the timing pointer on TDC, then turn the crank until the timing marks align on the camshaft and cam tower then measure your "stretch" in degrees on the crank damper. If you're >5˚, you should consider an offset key and budget for a chain replacement. If you're >7˚ or if an offset key is already installed, strongly consider a chain replacement in the very near future. If you're >10˚ stop driving the car until you get it repaired.

While you have the cover off, grab the chain on the cam sprocket and see if you can lift it off the sprocket. If you can, the tensioner isn't working properly or the chain is very seriously stretched.

For occasional lumpiness/bucking I'd be looking squarely at accelerator linkage rods being out of adjustment and the rubber fuel lines under the hood. All of them. If they're old, or if you haven't personally replaced them, use some 7mm fuel line and NEW fuel injection style clamps and replace the lot. If you have the old style "white handle" primer pump on the lift pump 86 that and get the updated one-piece replacement. Leaky hoses or leaking primer handle will let air into the fuel system and cause all sorts of unrefinement.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Well, i've been a bit held up from progress because my main tool box was stolen out of the trunk a month ago while parked in an area of town that's not so ideal. Gated lot, but creepers will creep. Lost ALL of my various types of wrenches and sockets, and specific hand tools that i had collected for this vehicle. Good chunk of change lost.

I have a question about the lumpiness...
In the next couple weeks I'm going to replace the rubber fuel line hoses and clamps, and also i'm going to drain the fuel tank and clean the fuel tank filter and replace the three rubber fuel lines under tank, but i'm still wondering about something...
Why would lumpiness suddenly dramatically increase when putting the car in park after coming to a stop? What would that indicate? I feel like that has to indicate something...?

I have twice replaced the pre filter in the past week in hopes that clearing the soot from the equation would be the answer. But it's not, the lumpiness still occurs. Will be replacing main fuel filter again too this weekend. It was last replaced in November.

I hope they didn't damage the trunk lid too much when they broke in .

define 'lumpiness' ~ are you talking about lack of a smooth idle ? .

Is there any visible crud in the clear plastic fuel intake screen ? .

There are only two fuel hoses needing changing underneath the fuel tank, be ready for a Diesel bath no matter how you approach it .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Crud: Yes, black specs. Lots of them.
In the fall i put a new pre filter and secondary filter in, when i did the diesel purge.
Last week i replaced it. It had a bunch of black particles.
I ran it for two days, went through a full tank for a road trip with family, then replaced the pre filter again. The 2 day old one i took out had lots of black particles again.
So i'm now on my third pre filter in just under a week. I took a look this morning and there were some black particles but not too much yet.

Lumpiness: It can sometimes be VERY out of control feeling. Almost like all 5 valves are hitting at the same time. It's scary.

-When i start first in the morning, it's smooth in park.. then upon driving a couple blocks and coming to a stop sign, it is VERY lumpy.

-When the car is warmed up, and i pull into park and am about to shut down.. once i put it in park it can sometimes start gradually lumping and if i let it keep rolling for 30 seconds it may end up in full lump action.


Air:
1: If it's air in the fuel system, was it there for the last six months since the diesel purge perhaps causing it?
2: OR, is it that i have some faulty issues with fuel lines that continually leaks air in?

It turns out i have the newer primer pump design, not the old plastic top one that leaks. This one appears fine and certainly works.


Valve Adjustment: Been reluctant to have someone do it because i know i can invest in the tools and do it myself. But now that my tools are stolen i would have to get a whole bunch of tools again so i'm going to just bite the bullet and hire the guy to do the valve adjustment this week.

Fuel lines by tank: I had learned that there are two return lines and one source line, and to replace all three as well as clean out the tank filter. No?

Trunk: i left it unlocked. Doh! No damage though. They just pressed the button i guess. Jerks.

I will get some Biobor!!!!