And may I mention that the offending lock nut was very stripped indeed? Can't call it a victory until she's entirely back together and clattering away (I have a personal policy against working late into the night; haste and fatigue are a great recipe for mechanical disaster), but thanks for the help you've all given me so far.

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1992 300D 2.5T 249k - Parked with a bad transmission
1981 300SD 142k - Daily driver

Great policy. I get home from work about 5:30 - 6 since it's a 62 mile one way commute, and my cutoff on car work is 7:45. Saturdays when the body agrees I'll do 10 hours straight .

Same rule on gunsmithing, did some stupid/expensive mistakes before realising things can wait till tomorrow.

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Eric, CPO, Submarines, retired.
Here's a sig line...
Mine: '68 Corvette LS1/4L65E, 83 240D, 2000 GMC 4x4, 08 FLSTC Anniv
Hers: '72 Corvette 454/4spd, '99 MB SLK, '93 Metro vert, 78 240D, '92 Silverado, '65 Fjord Rustang, '59 Fjord Fairlane, '17 Slingshot.

And she's up and running!

The idle is not as smooth as I'd like, I can't say it's smoother than before the valve adjustment. Perhaps the adjustment highlighted some other problem, perhaps injectors? It seems to miss (but not consistently) a little bit, but it's entirely driveable, and I haven't gotten the engine warm yet.

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1992 300D 2.5T 249k - Parked with a bad transmission
1981 300SD 142k - Daily driver

Well, glad to hear it's going! It is worth a doublecheck to make sure you didn't get any intake or exhaust mixed up. I only say this because I have.

The 300CD was a very incremental improvement, it's now as smooth as a gasser, but there is a video in some old post of it shaking like a $20 lap dancer in Esquimalt.

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Eric, CPO, Submarines, retired.
Here's a sig line...
Mine: '68 Corvette LS1/4L65E, 83 240D, 2000 GMC 4x4, 08 FLSTC Anniv
Hers: '72 Corvette 454/4spd, '99 MB SLK, '93 Metro vert, 78 240D, '92 Silverado, '65 Fjord Rustang, '59 Fjord Fairlane, '17 Slingshot.

Consolidated "how-to" for this job:

1. Remove necessary throttle linkage and vacuum lines, remove valve cover, remove air cleaner housing.
Just as you would for a valve adjustment. Removing the air cleaner gives you excellent leverage for the rocker towers.

2. Remove the three (or two) hex-headed capscrews for the rocker assembly you're removing.
These take an 8mm hex key.

3. Rotate the engine by hand to the "sweet spot" where the rocker assembly you're removing doesn't have any cam/spring pressure.
The best spot for the aft group (set of three) is pictured. The exhaust valve for the No. 3 cylinder is at the 12:00 position.


4. Pry up to remove the rocker assembly from its guides (one guide per tower), then lift out.
A medium-sized flat-head screwdriver, as shown, worked well with a little bit of force.

5. Rotate the engine to TDC for the affected cylinder.
The cam for the intake valve will be at 11:00. This prevents dropping the valve into the cylinder when the nuts are removed!

6. Remove and replace adjustment nut and lock nut.
I used the "third wrench" to compress the valve spring while initially threading on the lock nut. After both were on, I used valve adjustment wrenches to compress the spring so I could get the rocker assembly back on.

7. Rotate the engine back to the "sweet spot" for rocker assembly re-installation.

8. Push rocker assembly down onto guides.
Ensure that they're lined up, or they won't seat. Tap them in with a small dead-blow hammer.



9. Coat threads of 8mm hex-head capscrews lightly with crankcase oil and reinstall hand-tight.
These should turn by hand until seated. Resistance indicates that the rocker assembly is not seated properly and should be reseated.

10. Torque 8mm hex-head capscrews to 38 n-m (28 ft-lb).

11. Adjust the affected valve.
Might as well do them all while you have the cover off.

12. Reinstall air cleaner, valve cover, linkage, and vacuum lines

13. Have a beer!
Or two. Responsibly, of course.

Thanks to everyone for all the advice and help on this job.

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1992 300D 2.5T 249k - Parked with a bad transmission
1981 300SD 142k - Daily driver

Nice clear and concise writeup, Thanks !

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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

Maybe this ought to be made into a DIY stickie???

Great write up and pictures.


Charlie

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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

I added it to the list of Engine repair in the DIY links list.
PeachParts Mercedes ShopForum - Powered by vBulletin

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!