Snapped valve cover bolt.

myst1100

Joined
Feb 20, 2018
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California
Well, life was going well, lots of good help getting the valve cover access, new gasket and new grommets. Easy install until..

I got a manual (Honda manual) and figured I would look for the torque values for the valve cover.

Honda doesn't have anything called valve cover but they do have cylinder cover and they say 9 ft-lbs.

I don't trust my 1/2 torque wrench at that low of a value so I got a 1/4 torque wrench and it seemed like 9 ft-lbs was pretty tight.

And it was, I snapped off one of the bolts (before clicking on the torque wrench), I'm guessing I need a really sharp drill bit and easy out to remove it but figure I'll ask here first.

Also, I pondered doing hand tight but does anyone know what the valve cover should be torqued to?

Crap, I just looked at the torque wrench and it's in inch pounds, that's even more depressing. I'm thinking that I was backed too far out.

Woe is me..
bob
 
Bummer. If it’s any consolation you’re not the firST, Bob. I use the generic torque values listed in chapter 1: 9 ftlbs/108 inlbs. But hand tight works too. Carefully drill a hole for one of the reverse drill bit easy outs. Others may be along with other options. Good luck.

John
 
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If they're like most Honda cover bolts, they don't tighten like most bolts; the shoulder lands on the flat surface and there's no give.
 
That's bad luck, but can be recovered.
I completed my valve clearance checks last week (all in spec - yeah) and I used a 3/8" torque wrench to tighten the valve covers. However I was uncomfortable in doing so, as 9 ft-lbs is at the low end of the setting range on the 3/8". So I tested the 9 ft-lb setting by putting the 3/8" wrench square in my vice and feeling the torque when it clicked (second opinion). It seemed fair, as I eyed the bolt size. So in went the bolts, still with some apprehension on my part, almost closing my eyes,, but no snapping occurred. Maybe time for a good 1/4" torque wrench (?)
D
 
1/4" or 1/2" have nothing to do with the torque rating. There are inch-pound and even inch-ounce torque wrenches. All have a place. I believe that accurate torque is more important with delicate mechanisms at low torques rather than less. Be sure to mask well for debris if drilling. You might rig up a vacuum nozzle close to the drill point to take away swarf. Mounding grease around the hole works well, but the pieces can go quite a distance. Use as little drill speed as necessary. The pro solution is to fabricate a drill sleeve on a lathe and do it with the cover on. That guarantees no debris; no damage o the thread boss; and, a center hit on the broken stud with the drill.
 
Regarding your current problem, I've never had any luck with ez-outs, they typically break off because they're a fraction of the diameter of the bolt that's stuck. The only luck I've had is drilling the old bolt out gradually until just the threads remain and chasing the hole with a tap. If you don't have much experience with this I'd suggest getting a professional to do the work so you don't end up causing more damage to the head trying to remove the broken bolt.

Not trying to rub salt in your wounds, just posting it again to help prevent someone else from making the same mistake. I wrote this in your other thread a week or so ago:

I never use a torque wrench on the valve cover bolts, they just need to be snugged up by hand because they bottom out on the head via a shoulder at the lower part of the bolt that's hidden inside the valve cover. The grommets determine how much pressure will be applied to the gasket by the valve cover after the bolt bottoms out. If for some reason your torque wrench doesn't release properly when the bolt bottoms out you'll strip out the threads in the head and be sorry you used the torque wrench in the first place.
 
Thanks all, I'm going try to drill out the bolt once my cobalt drill bits get here (not going to trust old bits with this).

I'll just take it real slow and cross my fingers.
 
dwalby said:
...If for some reason your torque wrench doesn't release properly when the bolt bottoms out you'll strip out the threads in the head and be sorry you used the torque wrench in the first place.
Click to expand...

Your caveat is the same regardless of why you had reached for a torque wrench. If the premise is true, then a torque wrench should never be used, because if it doesn't release properly then you risk damage from over-torque to the assembly. You are in less of a fix if you break off a snappy valve cover bolt than you are if manage to you extract the aluminum threads from a 6mm thread into an engine block. There are many of these with 6 ft.lb. (72 in.lb) torques that must be accurately torqued to prevent damage. They are even more sinister than shoulder bolts if over-torqued, because you do not have a step increase in torque when the shoulder bottoms. By time you feel the torque starting to fall off, you have already ruined the threads. With the valve cover bolt, in short order you will have the broken bit out and with a new bolt everything will be fine. Not so the pulled threads in a block.

The possibility of a failure to release is more a reason to have a quality wrench in the proper torque range (middle of the range is best) than it is to avoid the use of one. If you have a risky torque wrench, replace it with a good one. A torque wrench used at too low a percentage of its full scale will be less sensitive and less accurate as accuracy is a percent of full scale. If you think you can manually gauge torque more accurately than a properly sized high quality calibrated wrench, you are deceiving yourself.
 
Agree with your points Lee, and in fact whenever I use a torque wrench I always click it a few times to make sure the release mechanism isn't binding for some reason, and triple check my settings. My point in this context was the valve cover bolts don't need a torque wrench to begin with, and if you torque them lightly by hand you'll know when they're snug enough.

Introducing the torque wrench into the equation unnecessarily adds an additional risk, which the OP found out the hard way. Whenever you use a torque wrench, even a good one, there's a small chance it will not release at the proper torque, or that you accidentally set it to the wrong torque value.
 
dwalby said:
I've never had any luck with ez-outs, they typically break off because they're a fraction of the diameter of the bolt that's stuck.
Click to expand...
Neither did I until a machinist taught me not to follow the instructions when using tapered style screw extractor's explaining that they don't make sense.
Drilling only one size hole in the broken fastener and then hammering in and forcing a tapered extractor is asking for failure. This leaves only a small contact area between the extractor and the fastener where the two diameters coincide. All of the stress on the extractor is being concentrated at this one point.

When I have to use an extractor of this type I drill multiple diameter holes in to the broken fastener- the number of different diameters being determined by the length of the broken fastener. The deepest hole will be sized small enough to allow the narrow tip of the extractor to bite in to the broken fastener in the bottom of the hole. I then drill progressively larger diameter holes that are also progressively shallower working my way up to the diameter drill bit recommended for that extractor at the top end of the broken fastener. These steps allow the extractor to bite in to the broken fastener at multiple points along its length spreading the stress on the extractor over a wider area.
I have been much more successful with the tapered style of ez-outs using this method. However, like you, I prefer to drill to the point where I can use a tap to remove the remainder if possible.
 
beemerphile said:
I believe that accurate torque is more important with delicate mechanisms at low torques rather than less.
Click to expand...
With older click type torque wrenches in particular, their accuracy would drop significantly when they were used at any setting that is outside of 15 to 85% of their range. Using them only within that range used to be a standard recommendation. I wonder if that has changed with newer torque wrenches. Torque wrench technology must have changed as I have seen some are advertised as being calibrated for life and never needing to be checked.
beemerphile said:
You might rig up a vacuum nozzle close to the drill point to take away swarf.
Click to expand...
Another method that works well with ferrous metals is to wrap a piece of flexible magnet sheet around the area where you are drilling. The drill bit will be in a magnetic tunnel that will catch the flying pieces of ferrous metal and hold them in the tunnel.

I no longer have an ST1100 and fortunately I never broke one of these screws when I did. Being a shoulder screw I would think that there would not be any tension on the threads that are remaining in the hole.
For those who have done this- would a left-hand drill bit spin it out quite easily?
 
Andrew Shadow said:
Torque wrench technology must have changed as I have seen some are advertised as being calibrated for life and never needing to be checked.

For those who have done this- would a left-hand drill bit spin it out quite easily?
Click to expand...
I rather doubt that torque wrenches have evolved so much as to change their performance over time. Even the high end T-W's (Snap-on, Mac, etc) offer recalibration services. Not having any idea of what brands you are talking about, I won't go on about this beyond saying those claims need to be checked in some depth.

I've used left hand bits and they work magically. Finding them (I have not looked for them recently) can be a bit of a problem. Fortunately, I have a machinist supply place near me that is very good and I've never had to go anywhere else. While my annual purchases there would not keep them in Whopper burgers for very long, since I was a friend of a v. good customer of theirs who introduced me to the owner and his staff, I've been treated well by them, and they have made brand recommendations to save money or to buy a quality cutting tool. That kind of service is well worth paying for.
 
Andrew Shadow said:
With older click type torque wrenches in particular, their accuracy would drop significantly when they were used at any setting that is outside of 15 to 85% of their range. Using them only within that range used to be a standard recommendation.
Click to expand...
Well, some basic mechanical knowledge should be anticipated... the best, delicate precise tools get distructive in the wrong hands... ;)
The factory torque values for each bold are there for a reason...
PS: it´s also mandatory that torque wrenches are released from tension while not in use/stored....
 
Sometimes when a bolt breaks off, the remaining piece is not tight at all and can be backed out with a small standard screwdriver, a couple of picks, etc... experiment. The bolt didnt break because the threads were tight and the bolt didnt bottom out, causing it to bind. I have had an instance or two that I can remember where I went to drill and the broken piece started screwing in. Give it a shot first.
 
Bmacleod said:
Sometimes when a bolt breaks off, the remaining piece is not tight at all and can be backed out with a small standard screwdriver, a couple of picks, etc... experiment. The bolt didnt break because the threads were tight and the bolt didnt bottom out, causing it to bind. I have had an instance or two that I can remember where I went to drill and the broken piece started screwing in. Give it a shot first.
Click to expand...
Yep, and if any of it protrudes from the hole you can sometimes create an ersatz screwdriver slot with a Dremel abrasive wheel.
 
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