1979 300sd

Adjusted 1st valve (Exhaust) and 2nd valve (Intake) and had no problems.

The 3rd valve (intake) for some reason just would not adjust to spec.
In the end the valve nuts would tighten up right back to where it was previously.

I got my 3rd wrench and positioned it directly on top of the spring so that it would not turn.

I went at it again and noticed that the bottom nut would spin around and would not lock. This had never happen before and so I got worried that I cross threaded or damaged something.

The top nut does lock on to the bottom nut but the bottom nut will not lock on to the top nut, again, it just spins and turns without stopping.

What can I be missing, did I over tighten something, was this nut previously damaged.

Puzzled

Note: If I tighten the top nut on to the bottom nut, the intake valve clearance is too much. I guess its better than being tight.

One other thing, how tight should these nuts be. I try to be gentle as much as possible but I also don't want nuts to be flying around

Please advise

Sounds like the threads on the adjusting nut(s) are shot.

To check this you need to remove the rocker arm set (for the valve with the trouble) and then position the piston at TDC or very close to the top of the cylinder so you can safely remove the valve spring (and nuts) and look at the condition of the nuts and the thread on the valve.

Make sure you know the piston is at the top of the cylinder before you undo those two nuts - dropping a valve in a cylinder is not going to help

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

How do I get TDC on the 3rd Valve?

Doesn't look good

I read thru this thread and it doesn't look good, and riding TDC is going to be a challenge because its valve #3
Frustration with W123 Valve Adjustment!

I can report that I can turn the lock nut clockwise and create space between both nuts, but once I start to turn counter clockwise as soon as it makes contact with the top nut it just continues to spin and not lock.

The top nut (adjusting nut) seems to be fine

OH boy....

Only thing I can say is that its a 5 cylinder vs a 4 cylinder so if there are any tips, please shoot them this way before I send it off to the shop.

Not going to blame anyone but myself. Both nuts were pretty tight before loosening so this indicates that it was probably cause by ME over tightening the nuts..

If you have an air compressor, I have read that an old glow plug drilled out to receive a hose with compressed air to hold the valve up/closed. Then just watch the cam, during the power stroke both valves are closed. Again I have not done it but it makes sense.

The thread you found has the answer in it.

That thread got out of control - so I hope we don't have a repeat of that again!

Here's the bit that might be of interest to you

So if you have the crank showing TDC and the camshaft notch more or less aligned then turn the crank by 216 degrees and the piston in cylinder 3 will be at TDC (half a turn is 180 degrees)

Alternative ways of solving at the problem are:-

1) Look at the valve train. On an OM617: when both cam lobes are pointing up in the air above a cylinder you are close to TDC (both valves are closed) the exhaust cam lobe is pointing left and the intake cam lobe is pointing right (as seen standing in front of the engine scratching your bits thinking how on earth am I gonna get this fixed)

2) Remove the glow plugs (on an OM617) and feel the air being sucked into or blown out of a cylinder. Make sure that air is being blown out - when it stops you've got TDC more or less.

Whilst this does not provide a super-duper accurate positioning of TDC it gets the piston far enough up the cylinder to catch the valve if you undo the nuts.

The use of compressed air (which has been suggested above) was extensively theorised in that thread linked above.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

That above thread did get a little out of hand.

Don`t want to read through it again.

Though there is some good info if you want to sift through it.

The second to the last post, here is what the OP did.

Frustration with W123 Valve Adjustment!


Stretch, you are always level headed and give good advice. Thanks


Charlie


sent from my pos computer

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Wish there was a pictorial to see the valve stem.

I'm just hoping that the lock nut is cross threaded and nothing else.

Not exactly a pictorial but some pictures here



From this thread

300SD OM617 Valve Seal Replacement Help

For example

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Just hoping the valve threads are OK.

By the way, how tight do you guys tighten the nuts.

I'm always paranoid that one of those nuts is going to loosen up

I ordered the adjusting nut cap and the lock nut today. Hope for the best

For some reason or other the valve clearances tend to "tighten" over time / during extended use - I haven't worked out exactly why they go that way and not loosen - must be a reason...

...but anyway chapter 05-210 specifies the lower nut (or counter nut) torque to be between 20 and 30 Nm

(So obviously that's how tight I do mine)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Oh yeah - forgot to say - on the whole (from reports from others) the nuts tend to strip out before the threads on the valve stems go. I think that this is because the threads in the nuts are cut and the threads on the valve stems are not only of a harder metal but probably rolled threads (which are stronger than cut threads).

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I thought you could tell when you were near top dead center when the Exhaust and the Intake Cam Lobe on the Cylinder you are interested in formed a "V" long part of the Lobes up.

If you are not sure how that looks put Number 1 at top dead center using the Pointer and the Crank Dampner degree marks. When it is on the Compression Stroke at Top Dead Center the long ends of the Cam Lobes on that Cylinder form a upwards pointing "V" when viewd from the front of the Engine.

That is what I did when I changed the Valve Stem Seals.

__________________
84 300D, 82 Volvo 244Gl Diesel

So KEY is to first find TDC on the 1st Cylinder, how do I do that?

Then If I find TDC at Cylinder #1 how do I get Valve #3 at TDC?

Is valve #3 on Cylider #2, yes, right?

So I'm trying to get Cylinder #2 at TDC (Top Dead Center)

I have heard of placing a finger in the glow plug opening (plug removed) and when you feel air blowing out, you got it. Sounds easy and thats why I know that its not that easy.

Lets just say I was to get that far, then what? How do I remove the damaged nut?

Do I remove that tension wire (tension bracket) that holds the 2 rockers and then go from there?

How do I remove the tension on the valve spring and how will it be kept compressed so that the nuts can screw off.