The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Crossrodes on June 19, 2009, 05:58:12 PM
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Long story short....I have a stripped centre stud on a valve cover. Instructions I have from somewhere call for a torque value on this stud for between 22 and 26 Newton Metres. I torqued it to 24 and it stripped before I got there.
Can anyone verify that 22 to 26 NM is the correct torque for this stud?
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I can't find a torque value for the nut in the owners manual, I'll keep looking .
If I had to go out on a limb, the torque you stated is at least 2 times what it should have been, but that's kind of obvious now .
The torque you stated is about what the spark plugs should be torqued to .
My normal 'torque', is just snug, I've got a palm ratchet, and I use my non-dominant hand to tighten items like this .
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A HeliCoil will fix you right up, CrossedUp. Available in a nice, economical kit at your FLAP. Have one in the right side head on my R65 thanks to an over zealous, knuckle dragging PO.
Just snug 'em. The center stud and those little studs and nuts fore and aft on the valve covers, too.
BTW, don't buy into the manual's torque specs for the fork lowers drain plug. The proper tightening torque is achieved with a stubby wrench and a gentle tug.
Monte
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Thanks but a heli-coil is not needed. I should have said that the cap nut is stripped...not the stud. I have two new cap nuts ordered.
I got the torque numbers from the Airheads web site. I just re-checked to see if I had misread it...I hadn't.
http://wiki.airheads.org/index.php?title=Valve_Adjustment
Oh well. you live and learn.
I was hoping that torquing it down would solve the oil leak I have from the valve cover. The strange thing is that I torqued down both covers and the other one is OK.
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How does the paper gasket that goes between the valve cover and the cylinder head look ?
When I had the valves and seats replaced, and the exhaust threads repaired about 11 years ago, I got a call from the shop, and they said that the surface on the cylinder head that contacts the valve cover, was warped and needed to be machined flat .
So maybe if you use two paper gaskets, it may eliminate the leak .
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the pound-feet to N-meters conversion is often fraught with turmoil, so I generally stick with my pound feet numbers - and that acorn nut or the (2) valve cover nuts on either side should only go to around 10 ft-lbs or about 13 Newton-meters... maybe you can go up to 15 N-m on the valve cover nuts (upper left/lower right fins side) but that center acorn nut should not go above the 10 ft-lb torque.
I have heard of BMW heads warping and requiring machining to correct - it can happen though no one seems to know exactly why - perhaps the alloy is just a bit soft for the area that it covers, combined with the large valve holes in it..
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The gaskets I used are both new and look good. When I first saw the oil leaking I removed the valve cover and dried the surfaces on both the head and valve cover. I then put a skim coat of Permatex black gasket maker on the lower surfaces of the valve cover and head and re-installed the gasket and cover. It leaks less but it still leaks.
I ordered some new gaskets from the BMW dealer on the phone this morning and asked them why this would leak. The parts guy asked the mechanic (who seems to be fairly knowledgeable) the same question. His response to the parts guy was that I should be sure to TORQUE the centre stud before I tightened the side nuts. Originally I had just tightened the stud and nuts to "wrist tight" using a short ratchet (I don't remember which I tightened first). Then I went looking for the torque value...it isn't in the Clymer manual and I found it on the Airheads site.
Prior to installing the valve covers I had cleaned up the surfaces on the head and cover so that they looked good but who knows how even they are. I expect, now that I have used the Permatex, that the gasket will be stuck to both surfaces and I will destroy the gasket when I remove it. That's why I've ordered more new gaskets. I'll try the mechanic's advice this time by tightening the centre first and then the side nuts. The ironic part is that I've had the valve covers off a couple of times before and just re-used the old gaskets and had no leaks.
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I have used two gaskets before, with good success.
I also gave up on the acorn nuts and the studs, and ran without them, using only the two edge fasteners.
No leaks.
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Maybe the acorn/cap nuts are a good thing if they are designed to strip BEFORE the stud strips in the head....Would BMW have been that smart when they designed the bike???
A friend is going to loan me a new gasket tomorrow so I'll check the head for warpage with a steel rule after I get it cleaned up. If it's warped I'll go the double gasket route.
Thanks for your input all.
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The threads in my heads always stripped before the threads in the acorn nut.
I can't imagine how that could happen. Alloy vs steel? Weird.
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It's early here and we haven't hit the road yet so wanted to add to Crossrodes possible leak fix.
The rocker box cover gaskets on my R65s are thick gasket stock. Under pressure, they actually deboss to fit any small irregularities of the cylinder head / rocker cover. I noticed this during a valve adjustment.
I also noticed a small oil leak at the gasket junction after doing the valves. What the...? Guess what the issue was and how simple it was to correct... I had accidently swapped gaskets side-to-side! Returning them to their home head stopped the leak. No gasket sealer required.
I now use a Sharpie marker to denote which gasket goes on which side and the surface contacting the rocker box cover -face in / face out. OK, this effort may be way too anal but I don't have niggling oil leaks... at least, not at the rocker boxes.
Now... Where's the bar on this tub?
Monte
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Good tip Monte. I had used two new gaskets but I wonder if given a little time that the gasket would form and seal.
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I know you asked about torque but I wanted to mention a reusable gasket that I'm really pleased with. I've had these for about three years and they've been on and off several times with no leaks. I've never used a torque wrench on the covers but like others just snug things up by feel to give it some squish* not to crush it.
rich
http://www.realgaskets.com/
*A term not found in Haynes Manuals = @ 7-10 ft-lbs
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Thanks for that tip. I've added their web site to my favourites. Right now I have a new set of BMW gaskets on order so if that doesn't solve the problem I'll get a set from these folks.
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Wellll it turns out that Rob was right :-[. The cap nut was not stripped (I thought when I looked at the profile of the thread that they were). What was stripped were the threads in the head.
I bought a helicoil kit today and installed it. Boy those suckers are expensive up here...$54 including tax for the kit. This will teach me NOT to believe everything I read on the web :'(.
Incidentally a friend of mine told me that because helicoils are so expensive he uses JBWeld for jobs like this. Comments anyone?
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Someone here abouts once said, IIRC, "There are some folks on this site that would get in a lifeboat made of JB Weld." He was not a fan.
Personally, I'd stay with the helicoil insert. I have one in the right-side head of my '81. As yet, no problemo. Just don't over-torque the puppy. Short wrench and just snug enough. Monte
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Yes I used the helicoil.
It's interesting what you said about a boat. It's a long story but a friend of mine once had the casing of a water pump on a Perkins diesel on his boat crack. He was away at the time and his wife, who was living on the boat, asked me if I could fix it. We were in the Eastern Caribbean and I needed to get this fixed for her asap.
I used JBWeld on the pump and now, 11 years later, that pump is still working. The boat is in New Zealand.
JBWeld is amazing stuff. I just hesitate to use it in an application where you have a threaded fastener.