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Bad crap just happened. Broken cyl head cover bolt!


Trobinson

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I was reinstalling the cyl head covers yesterday after checking valve and rocker arm clearances and the threads for two bolts on the left side and one on the right stripped. This morning I started on the left side and put thread inserts in the bad holes. The two front holes are the ones that stripped out. I went to install the cover and the top screw went in nice and smooth, but I had resistance on the lower screw (the rear lower screw also has resistance after having done the same repair about a year ago). I wasn't too concerned up to the moment when there was no resistance at all! I removed the cover and found the screw broken off in the head. With an insert installed will an easy out be the best way of removing the broken screw?

 

http://i1172.photobucket.com/albums/r580/tjrobinson2000/BMW%20R1100%20RT%20Pics/20150531_1129071.jpg

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Very hard for most people to keep a drill lined up to put a hole in the bolt without slipping up and drilling into the soft aluminum at the thread/bolt interface. And easy-outs are brittle and have an annoying tendency to snap off.

 

The #1 concern is the relatively thin-walled boss -- *very* easy to crack and break off a chunk. I picked up a motor that had been down on the left and found a cracked/broken side wall; it took a trip to a machine shop that could TIG aluminum to rebuild the boss and thread it.

 

If you think you have the equipment (drill press) and/or the ability to drill the center of the bolt, you could use a left-hand drill bit to drill into the bolt. The drilling in the "reverse" direction may be enough to walk the bolt out by itself.

 

Otherwise, take the head to a machine shop before the relatively small problem becomes a big problem. They also can address the thread inserts at the same time.

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Afternoon Tom

 

No way an easy out will remove that, easy outs are mis-named as they should be called "easily broken off's"

 

When a screw sticks enough to twist off then it is weld time or drill it out time.

 

You can core drill that one but that one sure isn't the one to practice on (very difficult drilling without a guide to keep it straight & centered). If you do decide to drill it out then start small, then once a straight hole switch to progressively larger left hand drill bits.

 

My personal way of getting those out is to put a (non-plated) washer over that broken bolt, then center weld the washer to the broken bolt through the center of the washer, THEN tack weld a nut to the washer (with the welding heat & expansion they usually back right out.

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After careful consideration (coupled with the fact I do not own any welding equipment) I'm going to pull the head and have a machine shop do the work. I'm going to pull both heads and take this time to de-carbon the pistons if needed and clean up the valves. I'll check the valve sealing, which I expect to be fine, and probably have the machine shop clean up heads.

 

My other thought is to have heli-coil inserts put in the other cover screw holes so I never have to deal with the threads stripping again.

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Tom in the past I have used various snap-on sets with left hand drill bits and they do tend to wander and of course the smaller the drill bit the tougher it is to apply pressure.

The beauty of these is that they are short, stout and you can apply a lot of pressure.

 

The other trick I have used in the past is to use a piece of flared steel brake line with a 1/8th drill bit inside it. Hold the brake line and drill away.

 

 

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I already have the left cylinder removed and will just trust a machine shop to do the work. I think this particular hole will need filling and re-drilling/tapping. I'll also ask them to put an insert in the upper right where there isn't one and I'm going to remove the right cylinder to clean both up and have them pretty much the same.

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Rocketman51

How hard was it to get the head off. My right front top valve cover bolt is only holding by a few threads. Are you putting in heli-coils all around?

 

97 R1100RT

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How hard was it to get the head off. My right front top valve cover bolt is only holding by a few threads. Are you putting in heli-coils all around?

 

97 R1100RT

no need to remove the head to helicoil the cover bolts, slather some grease on the drill bit to collect the swarf and have at it :D

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Rocketman,

I am going to have a machine shop do this for me and put inserts at all holes that don't have them. Removing the heads is pretty easy, but as mentioned not needed just for this work. Cover everything and go easy and you can do it on the bike. I just screwed one up which is why I'm taking them to a machine shop.

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  • 2 weeks later...

I just got the heads back and all the screw holes are good now. I was about to start mounting the right head and found a plastic piece sitting under the lower chain guide which turned out to be part of the upper chain guide.

 

Question now is will it be fine to run as is? I don't know if this piece broke while removing the head or if it was already broken (would expect it to end up in the bottom of the engine if that was the case). It's clean enough to super glue it, but I'm certainly not keen on that solution. The worst thing I see is it will wear down the edge. Thoughts? I don't really have the time or money to tear split the bike and tear down the engine to replace the guide right now.

 

http://s1172.photobucket.com/user/tjrobinson2000/library/Mobile%20Uploads

 

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A couple more questions. One, per the Chilton's manual the right side is supposed to be installed first. Is this really necessary? Two, they show the timing marks on the crank and cam drive sprokets which requires removing the alternator support and front engine case. Again, really necessary?

 

Current state is the left cylinder is at TDC on compression so I figure install this head first, turn the engine one rotation 'til the right side is at TDC (which would be compression) and install the right head. Make sense?

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I just got the heads back and all the screw holes are good now. I was about to start mounting the right head and found a plastic piece sitting under the lower chain guide which turned out to be part of the upper chain guide.

 

Question now is will it be fine to run as is? I don't know if this piece broke while removing the head or if it was already broken (would expect it to end up in the bottom of the engine if that was the case). It's clean enough to super glue it, but I'm certainly not keen on that solution. The worst thing I see is it will wear down the edge. Thoughts? I don't really have the time or money to tear split the bike and tear down the engine to replace the guide right now.

 

 

Morning Tom

 

You have a broken cam chain guide. Not good news.

 

It probably broke when loosening the cam gear bolt-- OR-- the crankshaft was turned with heads removed.

 

Unfortunately that is a difficult repair.

 

Can you run it like that?????? Maybe, I have seen some run a long time like that & others make noise & further break the remaining guides on that side from chain flutter. (kind of a crap shoot)

 

Personally I would repair it now rather than chance future problems. (LOTS of WORK to replace)

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A couple more questions.

 

One, per the Chilton's manual the right side is supposed to be installed first. Is this really necessary?--- No, as that would mean you couldn't replace L/H cyl head without removing the R/H first.

 

Two, they show the timing marks on the crank and cam drive sprokets which requires removing the alternator support and front engine case. Again, really necessary?--- No, you can use the flywheel TDC marks for TDC & use the removed cam gear position for reference of stroke.

 

Current state is the left cylinder is at TDC on compression so I figure install this head first, turn the engine one rotation 'til the right side is at TDC (which would be compression) and install the right head. Make sense?---YES, the engine pistons are at TDC on both sides, whether or not on compression depends on the cam timing when reinstalling the heads.

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I just got the heads back and all the screw holes are good now. I was about to start mounting the right head and found a plastic piece sitting under the lower chain guide which turned out to be part of the upper chain guide.

 

Question now is will it be fine to run as is? I don't know if this piece broke while removing the head or if it was already broken (would expect it to end up in the bottom of the engine if that was the case). It's clean enough to super glue it, but I'm certainly not keen on that solution. The worst thing I see is it will wear down the edge. Thoughts? I don't really have the time or money to tear split the bike and tear down the engine to replace the guide right now.

 

 

Morning Tom

 

You have a broken cam chain guide. Not good news.

 

It probably broke when loosening the cam gear bolt-- OR-- the crankshaft was turned with heads removed.

 

Unfortunately that is a difficult repair.

 

Can you run it like that?????? Maybe, I have seen some run a long time like that & others make noise & further break the remaining guides on that side from chain flutter. (kind of a crap shoot)

 

Personally I would repair it now rather than chance future problems. (LOTS of WORK to replace)

 

I agree replacing it is the best way to go, but the LOTS of WORK part is my dilemma. I need the bike on the road asap as it has been my daily commuter (cars are just way more expensive for my commute). I looked up the cost and it's only $12, but the time involved (plus the dealer is closed today & tomorrow) is my main issue.

 

I don't see how removing the cam sprocket bolt or the crank turning with the head off (I do have a locking pin of sorts in the flywheel) could break this. This is the upper guide for the right side, not the tensioner guide. When running the chain will be pulled against this guide first with the tensioner guide taking up the slack. I've not heard (to the best of my knowledge) any chain slap.

 

Regarding the work involved the Chilton's isn't much help here either. They show everything with the engine off the bike. I'd prefer to do this on the bike. Anyone know of a writeup somewhere?

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I don't see how removing the cam sprocket bolt or the crank turning with the head off (I do have a locking pin of sorts in the flywheel) could break this. This is the upper guide for the right side, not the tensioner guide. When running the chain will be pulled against this guide first with the tensioner guide taking up the slack. I've not heard (to the best of my knowledge) any chain slap.

 

Regarding the work involved the Chilton's isn't much help here either. They show everything with the engine off the bike. I'd prefer to do this on the bike. Anyone know of a writeup somewhere?

 

Afternoon Trobinson

 

If the chain jumps as the cam sprocket bolt is broken free it can break the end off of the chain guide.

 

As to replacing the guide-- Book says the engine has to come out & be split apart, even then it is lots of work.

 

On the few I have done I always do it the correct way & remove engine & split it apart then remove bolt & properly re-seal pin.

 

There are a few that have broken the old guide out (where the pieces go I have no idea) then open the end of slot on new replacement guide ,then slide it on over the lower pin. You still heave to access & remove the upper retaining bolt/pin.

 

I can't guide you on this as I split the engine & do it correctly.

 

If you search the web you should be able to find the cheating method if you look long & hard enough.

 

 

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Dirtrider,

 

Thanks much for your input. I do prefer to do it right as I don't want to have pieces falling into the crankcase. I'll have to think about this a bit and I'm certainly not going to pay a shop hundreds of dollars to replace a $12 part.

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szurszewski

...since "removing" the engine really means taking the bike apart from around the engine, I think you're looking at double digit hundreds to replace that part....

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Alright, the motor is back together and fired up first try! Sounds smoother than before. Now just on to TB balance and she'll be back on the road! I did check the valve clearances and made only slight adjustments to a couple of valves. I left the right upper cam chain guide as is as I didn't see that there would be any problem with it.

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Rode the bike into work today and it feels good! She's still pretty buzzy above 4500 rpm or so, but pulls strong (stronger perhaps? or maybe it's just been so long...). Anyway, no issues and it feels good to have gotten this work out of the way.

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