So you replace or correct your chain because it wears and gets longer.

What event happens to necessitate injection timing adjustment?

The timing chain drives the injection pump. Where as a stretched and worn chain might have caused certian injectors to fire mere milliseconds too soon or too late. With a nice, tight new chain, there is no delay, it fires right on time. Picture this, I have a 10 foot long rope, and we are playing tug of war, the rope is nice and tight, as soon as I yank the rope, you are going to feel it. If the rope is 12 ft long, and there is slack on the ground, I will have to spend a few extra seconds pulling the slack out before you feel the yank. Injectors getting worn out will also change the timing, they pop too early because their pop pressure is no longer 135 bar, or 115 bar for 240d (as stated on the sides of my injectors), Getting higher pressure injectors can also affect timing. Basically, after a timing chain replacement, you are just assuring that the injector pump is still set right. Better economy, and smoother running.

I have a much different take on this situation...
I would assume that the timing had been reset a few times over the years the first chain was wearing... thus a new chain would automatically be assumed to have changed the injection pump timing to where it needed resetting.
It is not all that hard or complicated either... so I would suggest there is no reason not to consider resetting it with a new chain as SOP...

It would be nice if the chain was the only thing that was wearing.

All of the Gears that drive the chain or are driven by the chain wear some.

Also inside of the IP the Camshaft and the Pins, Bushings, and Rollers of the IP Tappets also wear.

Of coures if you are happy with they way your Car is running; your call.

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84 300D, 82 Volvo 244Gl Diesel

That would be my take also.

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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Great Topic! Considering all else either replaced or in good working order (ie injectors, new chain, new rack damper bolt, clean filters/tank strainer, mounts, motor shocks, etc). Would a hot idle shake (never shakes when cold), be the result of poor IP timing OR a weak IP. (270k on the clock).

Compression is good in all pots with minimal/slightly moderate blowby.

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There is not an exact answer to the above questions. One of the other members speculated that it has to do with the total wear on everything in the Engine (or the fact that everything does not wear evenly). The wear in various parts of the Engine adds up and produces a resonance that causes shaking that shows up when the Engine is hot.In my case what took away most of the Shaking I will say 80% was rebuilding the Injectors. After that was new Motor and Transmission mounts. Lastly a new Governor Damper Pin took a way a little more.
I did not change the Timing Chain as it is not stretched much.So it is a lot of little things going on in the Engine that create the shaking.

As far as the IP goes when you rebuild one; one of the things you do is you put a Degree Wheel (the Test Stand has a Degree Wheel on the drive) and you Flow Time/Drip Time each one of the Elements/Plunger and Barrel assemblies to so that each one has the Begin Of Injection timed to the IP Camshaft to the specified degrees. (Some companies use a Degree wheel and you use a Dial Indicator instead of Drip Timing them.)

Depending on the companies IP the tappets are adjusted to achieve the above by way of changing Shims or making an adjustment on the Tappets (Please note you are not adjusting the amout of Fuel delivery but at what degree of IP Camshaft rotation the Fuel starts to be delivered.)

When the Tappet Rollers. related parts and the Camshaft in the IP wear the Begin Injection for each of the Elements can be slightly off.If you read the FSM there is a test to determine this. It has you check the Begin of Injection on one of the other Elements.

Also as the Elements themselves wear more Fuel leaks between the clearances of the Plunger and the Barrel of Elements giving un-even Fuel Delivery.
Hot Fuel is thinner and more hot Fuel leaks by the clearances and this makes Fuel delivery in an old IP more un-even when hot than it is when it is cold.

However, I do not believe it is worth overhauling an IP just to remove a little shaking since the shaking could also be caused by un-even compression.

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84 300D, 82 Volvo 244Gl Diesel

I read that the 'Rack dampner' was designed to correct something due to wear.. thinking ahead on the part of MB engineers...
What was it that it was supposed to fix when used in the fashion it was designed to do ?

If the IPs came with the Rack Dampner Pin when the IP was new how could it be there to correct some sort of wear?

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84 300D, 82 Volvo 244Gl Diesel