Hello. I recently purchased a 1972 280se 4.5 in good condition. After I finally got the engine started it had a noise like a lifter was clattering. I changed the oil to Castrol high mileage 20W 50, and it still made the noise. I then removed the valve cover and started checking lifter clearance, and sure enough I had a loose one. Number one intake was loose. The service manual said that all I had to do was adjust the 17mm adjusting screw to the proper clearance. I tried to turn it, but it wouldn't budge. The book doesn't mention loosening the 24mm compensating element. It looks to me like it is a 24mm lock nut that has to be loosened before adjusting the 17mm adjusting screw. What is the correct procedure for adjusting the lifters? Does it have mechanical lifters or hydraulic lifters?

Actually it has no lifters at all. The rocker arms you see act directly on the cam so they are actually cam followers and not rocker arms.

For one to be loose is not unusual. It all depends of the position of the cam to the arm at the time. If the lobe is pointing up then there will be slack on the arm and it is likely it will move some. In operation this is not a problem since the motion of the cam is so rapid there is no chance for the arm to bounce out of position. Plus it is held into place with a spring.

I don't have my books with me right now so I cannot answer the adjustment question. You should post this in the tech section, the vintage section, and ask for someone to tell you the proper way to adjust the valves.

The valves will need adjustment every so often since they are mechanical and there are no hydraulic lifters to self adjust on this engine.

If the lifter arms are dished out they will need to be replaced. Once they are dished it is impossible to adjust them with any accuracy. But they are cheap and easy to come by.

I don't know the Deatails on your specific Engine but way back several I had aquired some Valve Adjusting Tools and looked up stuff on them.

You will need to research it further but what I remember is the outer Part with the 24mm hex is not the Lock Nut.
The Center part is supposed to have a tight Fit and both parts are supposed to be replaced if the Center Part turns below a specific Torque.

So you are supposed to turn the Center Part, get your adjustment and leave it alone. The tight fit is supposed to keep it from moving.

Like I said you need to re-check to see of what I said is true.

It could be there is info in the Repair Links
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84 300D, 82 Volvo 244Gl Diesel

I think I found something.

This is step 5 in the Instructions: 5.If adjustment is necessary, take your valve adjusting tool and turn the adjuster - clockwise to loosen, counter-clockwise to tighten. If your tool won't turn the adjuster, you may have to remove the cam follower and use a deep socket to break the adjuster loose. After that your valve adjuster tool should work.

Step 12 if you need to remove the Cam follower: 12.Removing a cam follower requires first removing the little spring that holds the end of the follower, it should just pry off fairly easily. Then push the valve down, and the follower can be lifted off the adjuster ball and pulled out easily. There are special tools available for pushing the valve down. Note on top of the valve is a little cap with a slot in it that the cam follower sits in. The cap just sits there loose, just be aware of it. Don't forget to reinstall the little spring.

Pagoda SL Group Technical Manual :: Engine / AdjustingValves

Pagoda SL Group Technical Manual :: Engine / Start

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84 300D, 82 Volvo 244Gl Diesel

On the earlier gas engines the interference between adjustment threads was not as tight . So the valve adjustment would creep over time more. Always closing the clearance. Then they made a much greater interference or tighter thread fit on the adjuster.

Even the so called loose ones could be hard to adjust at times. There was a special offset tool you used with a small power bar. It has an open end with a forged loop that placed the socket to put the power handle into right above the adjustment over the arm.

The later ones can be so tight you will have to remove the rocker arm and get a real socket on some of them. Especially if you do not own the right 14mm tool if I remember the size correctly. It too may have changed size over the years. Any adjuster that is fairly easy to move in comparison to others should be checked with a torque wrench and replaced if below specs. Not doing so can result in a burnt valve pretty easy. Some of the later ones where extremely tight.

Expect to have to apply signifigant pressure to move them. A wrench in the hand is pretty much useless to adjust them. Incidentally it is very unusual to have excess clearance occur with that setup. Better have a look at the cam lobe carefully for wear. Mercedes made a lot of cams with the first lobe area quite soft in comparison to the rest of the cam. Or it was an oiling problem. Either way I had to have the lobe built up with weld and the cam reprofiled on more than one car.

If this turns out to be an issue there are probably good used cams out there cheap today for that engine. About the only way you can encounter excess valve adjustment clearance.

If the engine is running well is the lobe is worn unfortunately. Checking it against other lobes with a digital gauge is not a bad ideal. Or someone went at the adjustment with inadequate tools earlier.

In this design I have never seen a valve clearance increase. It always tightens the gap. If one is found the need to replace a cam with a used one might exist. You need the arms that were on that cam and reinstalled in the exact same places on the engine the used cam goes into.

Also I forgot to mention. The arms or cam followers themselves have a thin layer of really hardened surface wear material. On that one cylinder you want to pull the arm or cam follower and it is easy. Look at the area that contacts the cam to make sure that has not worn through. The visual difference between the surface hardness is so great compared to the remaining softer metal underneath it. It is obvious when the hardness is worn through. This is another thing that can cause the excess clearance you ran across. It can get so bad it in effect it machines the cam lobe it rides against.

My point is look for the reason the excess clearance exists in the valve clearance. Not simply adjust it. If it looks like only a very slight wear on the lobe adjusting it is probably okay. Only if you establish the wear is not being caused by the surface arm hardness being worn through.. If it is just replacing the arm or cam follower with a new will do no more harm usually. Do not use a used arm ever in a situation like that. There are existing surface wear patterns to consider.