Hi all,

Just completed a valve adjustment. Did everything by the book, got her all in shape. Double checked all the clearances before buttoning up, they were all if anything a tad loose, but the next size bigger feeler gauge wouldn't fit in there, so I figured it was ok.

It probably my imagination, but I'm thinking I hear a new knock. It does seem to be coming from under the valve cover. It is a lighter tap rather than a dull thud. It is barely noticeable, if at all, above 1,000 rpm. Under 1,000 rpm I can pick it up a little from in the car, better with the hood up outside.

Now I also have a very slight fuel leak coming from the number 3 injector. I'm assuming that this is because the injector return lines are worn out anyway, and I disturbed them when removing the valve cover. But I've read a little and maybe the injector could be bad?

I was careful to lock the bottom nut against the top adjusting nut when doing my valve adjustment, and did double check, but could I have left one loose and thats the problem? Car is running great otherwise. Maybe I'll try to get a video if the sound will show up at all on it.

__________________
1985 300D, 237k.
1994 F-350, 6.9 diesel, 5 spd manual, Banks Turbo. 261k.
Sold: 1985 300CD- 267K

It seems unlikely that you left a lock nut loose, since you have to tighten the two nuts together in order to check valve clearance. Just a thought here....when you did your valve adjustments, did you adjust the top nut to the proper gap..check with feeler gauge, and THEN tighten the lock nut? If so, you cant do it this way...when you tighten the lock nut, that will change the gap. When you do this adjustment, it requires a little trial and error before you get a feel for the interplay between the top nut and the lock nut, and whether you tighten the lock nut up agains the top nut, or tighten the top nut down onto the lock nut, or a little of both. You must tighten the two nuts together to their final tightness and THEN check clearance. When I do the job, after all ten valves are adjusted, I rotate the engine for one more go around and check all valve clearances...invariabley, there is one or two that I feel needs readjusting.


Another possibility is that you may have made a mistake and adjusted an exhaust valve to the intake spec, or vice versa. This could certainly result in a new tapping noise, since the gap is quite different between the two.

Good luck.

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

Agreed. BTDT.

I think I may have done this too.... Oh well. And I accidentally adjusted my dad's car the N/A exhaust clearances.... (.30mm rather than .35mm) So I might just pull both covers back off this week and double check/adjust them again. Oh well...gives me something to do. (school break week ) I did it right on our 300D (then again I spent way more time on it, since EVERY SINGLE valve was VERY tight) man does that one run better now....

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Hey, I thought I was the only one that did that!

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Sam

84 300SD 350K+ miles ( Blue Belle )

Talk about crestfallen.........first drive after five months of layup.........new head ........new valves...........new prechambers.............new starter..........new water pump.............new belts.........

...........and a definite ticking sound from the engine...........

Well, hmm. I did check the clearance after locking the nuts against eachother, and after I had it all done I rotated the engine once more and checked every exhaust and every intake valve to make sure they were all good. Maybe its just my imagination. I'll probably pull the valve cover again just to make sure, but will I need a new seal even though its new?

__________________
1985 300D, 237k.
1994 F-350, 6.9 diesel, 5 spd manual, Banks Turbo. 261k.
Sold: 1985 300CD- 267K

No you won't need a new seal (I am assuming you mean the valve cover gasket). You only need a new one after it becomes brittle with age and starts to leak...usually a couple of years. You can take the valve cover off several times during this period and you will be fine.

Just a hint here about leaking valve cover gasket....sometimes you will develop a leak even with a brand new gasket because the valve cover bolt pillars become distorted with age and dont allow you to tighten down on the gasket...instead you can only tighten metal to metal (you need to take a look at this next time you take off the cover and it will be apparent. To solve this, you need to file off about .5 to 1.0 mm from each bolt pillar...this will allow you to tighten the gasket more. You do need to be carefull, because this is designed in this way to prevent you from clamping down too tightly onto the gasket and distorting/cutting it causing a leak. You want to evenly snug-up the four bolts, then drive it. If there is a slight leak, then snug another quarter turn on each bolt.

regards,

Mark

__________________
1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)