This is on a 617 but notice that lining up the Pointer and the Tachometer Sensor is to separate jobs.
Timing marks gone from my OM617 engine

E300D timing chain stretch

Also there used to be Prechamber Tools in the Tool rental program.

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84 300D, 82 Volvo 244Gl Diesel

Browsing old posts it looks like if the two cam lobes are +/- 45 degrees with the top oil line, then the piston is at the top of the cycle.

Does that sound right? Does that guarantee the piston is at the top of its cycle or only ensure that the piston is at the top OR the bottom of its cycle?

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1984 300 SD 384,000 Miles

Last question for tonight. In browsing the FSMs it looks like there is an alignment mark built into the engine for setting TDC at cylinder one. I assume once I find that location I can simply rotate through each cylinder until I get to #4 where the cam lobes are pointed +/- 45 degrees with the center?

Thanks again for the help.

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1984 300 SD 384,000 Miles

That would be correct for a four-cylinder engine.

An '84 300SD does not typically have a four-cylinder engine.

Considering that you have previously defined "right" as being "toward the drivers side," is it possible that your informant properly understood that "right" is actually "toward the passenger side?"

Regardless, the intake lobe will never point to the driver side if the (same cylinder) exhaust lobe is straight up.

Ok, thanks for the confirmation. If the lobes are at +/- 45 degrees with the top oil line then is the piston at the top of its cycle?

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1984 300 SD 384,000 Miles

I finished this job last night and was able to hold the valve up using a strong pair of needle-nose pliers fed through the valve spring.

I do not recommend that anyone attempt a valve adjustment until they understand the exact mechanism for adjusting the cap and locking nuts. I certainly learned this the hard way. I was unhappy with the instructions I received on how to adjust the valves so here goes for future people who want to do this job on their own:

After the valve cover is off, take a careful look at the valve stems. There are 10 of them. The valve stem feeds up through the pre-chamber and is held in place by two nuts: the locking nut and the cap nut. These nuts are on top of the valve spring retainer. In my opinion, get yourself the special large third wrench to hold the valve stem. Mine wanted to rotate when I was doing the job. DO NOT MESS WITH JAMMING SCREWDRIVERS and foreign objects into the valve assembly to make it hold. First, I couldn't even get them to stay in place by forcing items in there. Secondly, it's not a wise strategy to force things and do things as not designed: I learned this the hard way by stripping the locking nut.

So there are three items on top of the valve spring, from bottom to top as follows: valve spring retainer - locking nut - cap nut. Realize that each wrench you need fits on each one of these nuts. The locking nut and the cap nut require the same size valve wrench even though the nuts look different. Notice that the cap nut fits ON TOP OF THE VALVE STEM. It cannot be threaded down beyond a certain point on the stem.

You will not need to rotate or adjust the valve spring retainer. The large third wrench I recommend you get is simply to hold the valve spring retainer from moving/turning (and moving the valve with it) as you adjust the cap and locking nuts.

The first thing is to get that third wrench on the valve spring retainer.

Here are the instructions I wish I had when I started this job:

1) The locking nut loosens with clockwise rotation. As you move the locking nut (i.e. the middle nut) clockwise, it pushes down on the valve spring retainer and will generate a gap between the locking nut and the cap nut.

2) The locking nut tightens with counterclockwise rotation. Realize that the mechanism by which it locks is by resting itself against the cap nut at the top of the valve stem.

3) FIRST, loosen the locking nut by turning it CLOCKWISE. There will be some pressure as you loosen it because it is "locked" against the cap nut. In order to successfully do this, you need to take your second wrench and hold the cap nut in place. In other words, hold the cap nut in place and turn the locking nut clockwise to loosen it. You will physically be moving the locking nut DOWN the valve stem so that you generate a gap between the locking nut and the cap nut.

4) SECOND, adjust the cap nut by turning it CLOCKWISE if the valve is too tight or COUNTERCLOCKWISE if the valve is too loose. Remember that you need to check valve clearance using feeler gauges between the rocker arm pad and the camshaft lobe. This is the region above the cap nut and above the pad that rests on top of the cap nut. The exhaust-intake sequence is documented elsewhere on this site so use the search function to find out the sequence of valves. Remember that if your engine is cold you want the exhaust valves measuring 0.35 mm and the intake valves measuring 0.10 mm between the rocker pad and the camshaft lobe. Also remember that the lobe of the cylinder in question needs to be at the 90 degree vertical with the rocker arm pad. That puts it in about the one o'clock position.

5) HERE IS WHERE I MESSED UP: Make sure you have loosened the locking nut enough before you fiddle with the cap nut, especially if the valve is too tight (which it probably is). If you don't loosen the locking nut enough by turning it clockwise (moving it down the valve stem), then the cap nut will quickly come to rest and "lock" against the locking nut (as you turn the cap nut clockwise to loosen the valve...i.e. increase the distance between the rocker pad and the cam lobe). MAKE SURE YOU LOOSEN THE LOCKING NUT ENOUGH SO THAT YOU CAN ADJUST THE CAP NUT AN ADEQUATE AMOUNT TO GET THE DESIRED SPACING. I recommend that when you do your first valve, loosen the locking nut 5-10 1/2 turns...i.e. until you see the gap between the cap nut and the locking nut. This will improve your understanding of what you are doing.

6) Remember that when you are loosening the locking nut by turning it clockwise at the beginning of this job, you need to hold the cap nut still.

7) Remember that when you are adjusting the valve clearance by turning the cap nut (up/decrease clearance or down/increase clearance) that you need to hold the locking nut still.

8) Once you have the desired clearance, TURN THE LOCKING NUT COUNTERCLOCKWISE and it will feed up the valve stem until it rests against the cap nut. Tighten it snugly against the cap nut. Remember that you need to hold the cap nut still when you are locking the locking nut up against the cap nut.

9) Your adjustment might get slightly out of whack when locking the locking nut up against the cap nut. If so, re-adjust. At this point, armed with this information, I think it is fair to say that getting it just right will be an intuitive process.

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1984 300 SD 384,000 Miles

No. Valves most certainly do not penetrate prechambers.

Valve clearance specifications vary by engine.

What is "90 degree vertical?" By most definitions, the cam lobe needs to be 180 degees from the rocker arm pad.

1) I assumed the valves fed up through the prechambers. I guess they don't. If they don't feed up from the prechambers then they must feed up from the actual cylinder.

2) True, check the sticker on the front cross-frame. My car is an 84 300SD.

3) True, that would technically be 180 degrees since the lobe makes a complete rotation. Better phrasing: make sure the lobe is pointing straight up with reference to the pad.

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1984 300 SD 384,000 Miles

This is what I had in mind concerning My comments on writing instructions for someone else to use.
The Person that writes the Instructions understands what the want to say but when it gets into actual Words the thought behind it comes out different.

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84 300D, 82 Volvo 244Gl Diesel

Note that many feeler gauges thicknesses stamped in MM and inches. German engines are in MM and may not have an exact .010 and .035 mm sized feelers. Don't use the wrong gauge or you'll be doing it over. At least the mistake will leave you with loose valves, not tight burned valves.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.