Valve Cover Gasket Replacement Gone Wrong

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Something that small, I have never used a torque wrench on. When you have been wrenching for awhile you get that "IT'S TIGHT ENOUGH" feeling and STOP!
I have installed BOO KOO SBC valve covers. These are the size/kind of bolts I am referring to.
Size of the fastener should not be a determining factor. The purpose of the fastener should be the determining factor.
 

GMFan

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So the shop drilled out the broken fasteners, replaced them and retorqued all the bolts. Picking the car up later tonight. Relieved to have my car back.

I still have to replace spark plugs and drain and refill the MTF with 75w90 as part of my 150k mile service. No torque wrench will be used 😂

I still love how this car drives and runs so I’m hoping with good maintenance I can get 250k+ out of her.

Main reason I get worried on manual transmissions with any oil leaks is keeping oil from contaminating the clutch.
 
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Tomato, Tuhmotto.......... 🤷‍♂️
Point is, I would definitely torque the M6x1 fastener holding on a timing belt tensioner. But torquing the same-sized valve cover bolt that has a built-in stopper? Maybe, maybe not.

But it is good to know what a certain torque value "should" feel like, even when using a torque wrench.
 
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FYI, many fasteners have a “standard” torque to which they are made to be tightened, depending on the type of material. It’s all about the grade of material the bolt is.

Example: 3/8” fine thread bolt grade 8 is approx 40 ft lbs.
 
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I don't think I've ever seen a 3/8" torque wrench with in-lbs on it, only 1/4". Especially your last picture shows it only goes up about 280 in-lbs? That's only about 23 ft-lbs.

Was this a cheap wrench? I wonder if it had the wrong markings on it or something.
 
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CDI has them.

cdi.png
 
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I have this Tekton torque wrench and have used it on the Nissan VQ40 valve cover and transmission pan bolts. I tightened mine in a series of three passes with the final one at 84 inch lbs. I have heard of many folks getting the inch and pound confused with these.
 

BlueOvalFitter

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Point is, I would definitely torque the M6x1 fastener holding on a timing belt tensioner. But torquing the same-sized valve cover bolt that has a built-in stopper? Maybe, maybe not.

But it is good to know what a certain torque value "should" feel like, even when using a torque wrench.
I never torqued differential cover bolts, transmission pan bolts, valve cover bolts, etc. And, none of them ever leaked. Imagine that...... :rolleyes:
 
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Point is, I would definitely torque the M6x1 fastener holding on a timing belt tensioner. But torquing the same-sized valve cover bolt that has a built-in stopper? Maybe, maybe not.

But it is good to know what a certain torque value "should" feel like, even when using a torque wrench.

+1 Small low torque bolts can be found in critical applications as you say and should be torqued. Did chain guids and chain on an Audi all were low torque and had a brown locker on the bolts from the factory. I used all new bolts not being certain as to what compound they used.
 

GMFan

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I pulled the engine cover and it appears the shop used M6 torx bolts to replace the snapped fasteners. I guess extra security to prevent thieves from stealing my valve cover like wheel locks. Although more likely it’s what the shop had on hand in terms of hardware. 😆
 
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Sometimes with low torque like that, its not enough to make a audible click. You may however feel the head of the wrench let loose with out it making a sound.
 
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Today I replaced a leaky valve cover gasket on my 150k mile 2011 Mazda6. Everything went fairly well with disassembly with exception of a couple stubborn plastic grommets to work the wiring harness to clear the valve cover. Some packing tape came in handy to tie it back once it was enough out of the way. Removing old gasket, and installing new was straightforward. I thought to myself "Gee this is going really smoothly." Famous last words...

I borrowed my friends Torque wrench with 3/8" drive. Luckily my neighbor came home while I was working an he let me borrow his 1/4" to 3/8" socket adapter so I could use my 1/4" drive 8mm deep socket on the 3/8" drive torque wrench I had. Such luck.

Buttoning back it up is where everything went downhill fast. So I set the torque wrench to 84in/lbs for the valve cover bolts with the nut head. I start torquing....hmmm. this feels like a lot or torque. I loosen and retry a bunch of times. No clicks from the torque wrench. At this point I get concerned. I watch YouTube video on how to use a torque wrench. A couple more trys and finally on the center bolts I feel the torque wrench click. Ok, its working now. So on the fourth bolt (top left of valve cover) I proceed with torquing and SNAP. That sense of dread filled me. Busted fastener. Crap. Well....I'm too far along now. It's going to be dark soon and I at least need to get all the wiring harnesses back in and this job wrapped up. I call my buddy and he says to use oil on the threads of the bolts because I may not be getting a good enough torque reading due to friction in the threads. So I unbolt all the valve cover bolts and oil with motor oil. I proceed to torque the first bolt and SNAP (The bolt in the center of the valve cover). At this point I toss the torque wrench away and just hand tighten to feel and move on.

The valve cover doesn't spew oil out everywhere, but I only drove it for half a mile and shut it off for the night.

So now that I can calm down from kicking myself I try to figure out my next step. What do with the broken fasteners. The broken fastener in the top left of the valve cover gasket looks like it could be worked/threaded out from the bottom possibly. But the 2nd fastener that broke in the center is the threaded hole between the 2 spark plugs in cylinder #2 and #3. How is that going to come out??? The fastener hole terminates in the engine head. How is that going to come out? How big of a pile am I in here?

Anyway, here are pics of the engine, and the carnage. https://drive.google.com/drive/folders/1ZawSIEiG0TAXekEMQd3JjNt3FvFH-5SD?usp=sharing

Time for a mental cigarette break tonight before I figure out what next steps are tomorrow morning. I may take it in to my trusted mechanic and see what they can do in terms of tapping it out. It's really that fastener in between the spark plugs that's got me very concerned.

Am I just an idiot who doesn't know how to use a torque wrench? I mean, one fastener snapping could be blamed on tired metal, but two? That makes me pretty sure I'm the idiot here. :cautious:
Been there done that bought the tee-shirt. Torque is not really necessary snug them starting in middle and work out
 
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With regards to torque wrench, I bought the 1/2" version of the AC Delco digital torque adapter for torqueing a few 200 lb+ fasteners instead of buying an expensive torque wrench for those few parts. They also make a 3/8 version.
Aside from that application, I use it to verify my torque settings on my torque wrenches before using on the fastener. I just test on a fastener that is more torque than what I am working on, usually a lug nut. I found that one of my wrenches is calibrated to the upper part of the offset line on the wrench's scale. There are some pros and cons to this adapter, but I like the piece of mind to see the numbers as opposed to waiting for the click. Not saying it would have helped in your application, but would have helped verify the wrench calibration.
 

D60

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+1 Small low torque bolts can be found in critical applications as you say and should be torqued. Did chain guids and chain on an Audi all were low torque and had a brown locker on the bolts from the factory. I used all new bolts not being certain as to what compound they used.
This is what I was thinking, too. Valve cover bolts = probably not a big deal.

But when I did a timing set on a Ford 3.5 I torqued everything for chain guides, etc. It's all internal thus can't be visually inspected later and failure is a BIG deal. I also like to torque plastic plenum hold-down fasteners but even then common sense must dictate - if it starts to FEEL too tight stop and quadruple check everything.

OP, a few pointers if you're trying to learn:
A) that Craftsman wrench was probably crap. There are plenty of YT vids on how to calibrate if you want to check it - you basically just need a measuring tape, something kinda heavy and a calculator
B) you should always "warm up" inexpensive torque wrenches by clamping the anvil in a vise and clicking it at desired setting repeatedly. This also affords a "common sense" check; if you're at a relatively low setting and yet you're twisting your workbench around the shop to get a click, something ain't right
C) at low settings many wrenches do not click at all but merely "slip" -- it can be virtually silent and is all about FEEL, not auditory perception per se
 

D60

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This happened to me once before on an intake manifold. I was able to get it out with needle nose pliers by grabbing the shank and twisting it out.

It looks like you can get it out with needles nose pliers and twisting it out as well.
These are a fun and useful addition to anyone's box. They actually have saved my posterior a couple of times, primarily with broken taps or drill bits
 
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Well, it's nice that the shop was able to get it fixed up for you. I've been there- snapped a trans pan bolt on a 4T65E. I'm still not sure what happened because the other bolts went on just fine. To my surprise, it didn't so much as weep at that spot, so I just left it. Torque wrenches have a lot less precision at the extreme ends of its rated torque values, and 7 lb-ft is going to be at the extreme low end for a lot of 3/8" torque wrenches. It sounds like there might've been a mechanical issue with it as well, with the brown fluid leaking out. Either way, lesson learned and hopefully the shop invoice wasn't too steep! Oh, and that is one clean engine. The Duratecs are good engines, but that's also excellent maintenance.
 
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Maybe you were waiting for a torque wrench to click that doesn't click. My 1/4" does not click, it only gives a slight bit when torque is reached.

Regarding the broken bolts, key to extracting is to start with the proper bit that's the right size and of high quality. Guesswork and throwing crap at it will make a big mess. I usually find the Dremel carbide cutting tip to be the best available locally for hard bolts but if the bolt is under say 1/4" that bit is probably too big.
 

CleanSump

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We tested experienced, knowledgeable, Navy/Marine aircraft mechanics from various rates/MOSs to see if anyone knew what "finger tight" was and if anyone could accurately guesstimate torque without a torque wrench.
There's a reason we never put "finger tight" in a manual and always list the proper torque and tool.
If anyone's calibrated wrist or fingers happen to match what a cal'd torque wrench says, it's accidental, not experience.
That was scientific testing by engineers that blew the cockiness out of many a sailor and Marine.

P.S. "Finger Tight" does not have a measurable value. Compare King Kong to Tweety Bird. They both do "finger tight"....

What's tight? Squeak plus a quarter turn.
 
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