I'm at wit's end with this one... I just changed the spark plugs on my E320. I discovered that three of the six-long 5mm screws used to hold the rectangular cap to the valve cover weren't even tight. I figured the previous owner was lazy. I replaced all six-screws with new ones since they were rusty on top and the allen recesses were starting to round off.

I easily got the screws for coil #4 to screw in nicely. I only got one of the two screws on coil #6 to grab, and on coil #2, neither screw grabs. I removed the cover ten-times and tried refitting it - that didn't work. I made sure the three coils were down far enough into position, I made sure the spark plug wires were all in position. I even made sure the rubber piece that goes along the side of the valve cover (under this cap) was in line. I tried screwing the screws into their holes individually without the cap and they all screw in perfectly. It's as if the screws for coil #2 and #6 aren't long enough. I also removed that spongy thin rubber gasket that goes around the perimeter of the underside of the cap to buy me another 1/4 inch or so - no luck. Has anyone else experienced this?

Orig screws were too short ..after many cover removals, the top threads in the aluminum head strip out from over-tightening b/c the orig screws did not have enough thread turns/depth to start with. They just caught by a couple of turns, so they could not hold the tightening torque for more than a few times . [ and some heavy handed wrenches really crank on them] Very Common on 104 DIS engine.
The remedy is to junk the orig 6/1 x 70 mm screws and replace with 6.1 X 75 MM And add a washer. The extra length gets you into the good threads in the head b/c of the added depth of the longer shank.

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A Dalton

No kidding. You mean go to the dealer and get the better screws? The guy who sold these to me wasn't that bright. Or do I go to a hardware store and buy these?

No..you have to go to a place that sells nuts/bolts in metric...if you can't find the extra 5mm in length, you can get the next size up and cut them...it is not a dealer item..they recommned helicoil the head hole, but this is an easier and better solution..that's all..


Got a bolt stretcher ?? ....

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A Dalton

Damn, that would explain why the bolts screwed in alone since the first few millimeters of thread were stripped but the bottom few weren't. My next step was to seek out a longer screw to remedy this but I wanted to make sure there was no TSB on it or maybe that I was doing something wrong. Thanks.

>


You did nothing wrong..it was the guys before you that did...they stripped the starting section of the threads cuz they were Heavy Handed Dumbcoffs ......some wrenching take Finese.................as all us old guys have a feel for .....
We have aquired a built-in torque feel from years of stripping threads.

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A Dalton

Non- recommendated note:

My bolt stretcher remark was a joke, but I had actullay done this on a couple of bolts that required a slightly longer shank.
I slipped the bolt thru a couple of larger nuts that were clamped in a vice [ one on each side of the jaws ] ..... I then put a washer on each end and a correct thread nut on the threaded end , heated the suspended shank in the center of the vice with a torch, and tightened the threaded nut when the shank got red ..As you tighten the nut , the shank lengthens the distance you turn the nut.... let it cool and you have a longer bolt..................
A Bolt Stretcher....

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A Dalton

Interesting, I was actually going to the hardware store soon to look for a "glass stretcher" and some headlight fluid, at least now I can cross the bolt stretcher off the list - whew.

That "Stretcher" thing came from the old carpenters who whould tell the new guys that would cut a board too short..."Better get the board stretcher ".... Then they would say " Measure twice , Cut once "...

I didn't last long on those jobs........

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A Dalton

what are you talking about? spark plug covers, rectangular cap to the valve cover? coils? this could be a matter of terminology but I must say...What?

Which Term/s are you having a problem with ??????

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A Dalton

all right...spark plug covers? rectangular cap? what the heck are you talking about? I still can't figure this out...if you feel like commenting go ahead but this seems beyond me...good luck however

<...good luck however >>

You are Correct ..that would be a waste of time.............

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A Dalton