Dreaded engine knock
 

Hey guys,

So our 220 has had a knock for awhile, when it idles it varies in volume like tah tah tah tah TAH TAH TAH tah tah TAH TAH tah tah tah kinda loud and metallic sounding... The only reason I decided to really look into it is because we just had the injectors replaced, got the car back yesterday hoping it would fix our smoking issue because she threw out lots of smoke.

Well we got her back and the knocking almost seems a bit louder to me, and she still throws out lots of smoke as well, some white smoke I saw with lots of black. I was thinking of doing a diesel purge but is that even necessary since the injectors are new? I've looked a lot more into the issue and all i'm really seeing that knocking is mean impending doom :(

Have I come to the crossroads of this doom???

Have you done a compression test ?
Are you sure the valves are properly set ?
Does it do more smoke upon start up than later when it is warmed up ?

I haven't done a compression test or know if the valves are set correctly, on the smoking issue, I would say warmed up, I mean she throws out some smoke on the initial start up but when building up speed to go to second and third/fourth gear there is a good amount of smoke, to where people move to the next lane constantly when behind me. On the freeway, if I step on it to go faster I see it in the rear view mirror and when I let off the accelerator I get a cloud of smoke.

Are you using a lot of oil... or does this appear to be unburned fuel making the smoke?
You need to check your chain elongation...
then set your IP ...
did you pull the precombustion chambers and be sure the little holes are clean...and the pintle ball is there... ?

I want to say we would add a quart every 2-3 weeks if we were driving her all the time, possibly unburned fuel not too sure.

I'll check the chain and see if there is any play, should it be super tight? How would I set the IP? I hate to admit that I'm not to familiar in this area of the engine, mostly just the front belts and whatnot.

1st things 1st.
SET YOUR VALVES.

Will do!

Check your alternator tensioner bolt to see if it broken. Some of the early w115s had a curved, long tensioner bolt which has a tendency to crack near the bend. I am talking about the type shown here:
New Original Mercedes Alternator Belt Adjust Adjuster Tensioner Bolt Support Kit | eBay
Anyway, mine is cracked and makes a metallic tapping sound as a consequence. This obviously wouldn't solve all your problems, but it is worth glancing at.

If someone has not mentiond this if it has a Pneumatic Governor if there is a leak in the Governor Diaphragm or the Housing where the shaft the Vacuum Leak causes excess Fuel.

Also if the Governor Diaphragm is not leaking it can just plain be stiff.

There is several threads on testing and replacing.

Governor Diaphragm Test
http://www.peachparts.com/shopforum/diesel-discussion/313733-74-240d-grey-smoke-questions.html

What are the symptoms of a bad IP Governor Diaphragm? Has Symptoms, Cost of Diaphragm, description of how governor works.
http://www.peachparts.com/shopforum/vintage-mercedes/223548-what-symptoms-bad-ip-governor-diaphragm.html

Governor Diaphragm
What are the symptoms of a bad IP Governor Diaphragm - PeachParts Mercedes ShopForum

What does the Exhaust smell like. Fuel or Oil burning?

I would consider that a lot of Oil being replaced if you are not on the Freway for like a 100 miles a Day.