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  #1  
Old 11-07-2010, 02:59 PM
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Adjusting valves - Nut bottoms out

Is it possible for the valve adjustment nut to bottom out? I'm adjusting my valves and it feels like the top nut has bottomed out against the valve stem. The middle nut is loose, and trying to tighten the top one makes the large nut against the spring turn. Is it time to swap my new engine in soon?
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Old 11-07-2010, 03:15 PM
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Originally Posted by 300SD81 View Post
Is it possible for the valve adjustment nut to bottom out?
Certainly. Should we infer that the bottoming occurred prior to attaining the specified clearance?
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Old 11-07-2010, 03:17 PM
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Quote:
Originally Posted by tangofox007 View Post
Certainly. Should we infer that the bottoming occurred prior to attaining the specified clearance?
Yes, its the exhaust valve on cylinder #5, the thickest feeler gauge I can fit in there is .28mm
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1991 Mercedes-Benz 560SEL | Megasquirt MS3-Pro | 722.6 transmission w/ AMG paddles | Feind Motorsports Sway Bar | Stinger VIP Radar | AntiLaser Priority | PLX Wideband O2 | 150A Alternator | Cat Delete
1981 Mercedes-Benz 300SD | Blown engine, rebuilding someday...
1981 Mercedes-Benz 300SD | Rear ended, retired in garage.
2009 Yamaha AR230HO | Das Boot

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Old 11-07-2010, 03:35 PM
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Have you tried actually holding the large hex just above the spring from turning while trying to adjust...?

Sometimes, you get some crud in the threads there and when setting the top cap it can tighten up--even though there is still adjustment there....
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Old 11-07-2010, 04:30 PM
300SD81's Avatar
1981 Mercedes-Benz 300SD
 
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Quote:
Originally Posted by Alastair View Post
Have you tried actually holding the large hex just above the spring from turning while trying to adjust...?

Sometimes, you get some crud in the threads there and when setting the top cap it can tighten up--even though there is still adjustment there....

Yeah, I clamped it down with vise grips, the top nut dosen't want to go down at all
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Ich liebe meine Autos!

1991 Mercedes-Benz 560SEL | Megasquirt MS3-Pro | 722.6 transmission w/ AMG paddles | Feind Motorsports Sway Bar | Stinger VIP Radar | AntiLaser Priority | PLX Wideband O2 | 150A Alternator | Cat Delete
1981 Mercedes-Benz 300SD | Blown engine, rebuilding someday...
1981 Mercedes-Benz 300SD | Rear ended, retired in garage.
2009 Yamaha AR230HO | Das Boot

Excessive speeding? It ain't excessive till I redline!
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  #6  
Old 11-07-2010, 09:51 PM
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Quote:
Originally Posted by 300SD81 View Post
Yeah, I clamped it down with vise grips, the top nut dosen't want to go down at all
When you are Holding the upper Sring Retainer Nut and you turn the upper Valve Nute does the Valve Stem Rotate? If the Valve Stem I rotating while the Upper Spring Retainer is held the Tab that fits into the Slot on the Valve Stem is Broken off.

Also if when you do the above the Valve stem is not moving and the Upper Nut is not moving; can you back the Nut off and close up that 0.2* clearance? To see if the Nut will move at all.
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  #7  
Old 11-08-2010, 10:07 PM
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NUT BOTTOMING OUT

Same thing happened to me. I ended up stripping two valve thrust nuts. Had to replace them. Barely squeaked by with enough clearance. Replacement valve thrust nuts seemed to give me the additional clearance, but that was it, no more. I will probably have to grind down the top of the valve for the next adjust. I think the valves are just wearing into their seats more. You might have a shrouding effect on the valves, but im not too concerned, because the air charge is pressurized. Im sure someone will argue that.

Hard to say its the end, my car only uses about a quart of oil every 10000 miles. And thats including a leak(dribble).

If you accidently strip the nut, thats ok. Only the threads on the nut will give, the threads on my valves were intact.
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