Valve Cover Gasket Replacement Gone Wrong

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2,092
Location
NC
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:
 
Messages
2,339
Location
SD
See last pic...just so I can prove im not THAT dumb. :ROFLMAO:
No, certainly didn't mean to imply that you're dumb...just mentioned it as something to check. I couldn't view your pics at first, but tried again, and apparently just didn't wait long enough the first time. Maybe torque wrench far out of cal?
 

GMFan

Thread starter
Messages
2,092
Location
NC
No, certainly didn't mean to imply that you're dumb...just mentioned it as something to check. I couldn't view your pics at first, but tried again, and apparently just didn't wait long enough the first time. Maybe torque wrench far out of cal?
I know, I'm just poking fun at myself. Believe me I feel dumb at this point. I've never used a torque wrench either honestly. But I figured for something like a valve cover it was necessary. Lesson learned. If torque isn't an issue on valve cover gaskets I would have just used my brain and stopped when it felt tight enough.
 
Messages
25,470
Location
MA, Mittelfranken.de
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:
Time to get a mechanic on the job, seriously. Those bolts are no big deal to get out as they broke going in not seized due to corrosion but you have to know what you are playing at or you can do a some more damage.
Basically I would insert a protective tube and just run the broken piece out slowly with a long left handed bit or a few other methods depending on what it looks like up close.

I would get all new bolts, the ones that didn't break are possibly stretched and strained and may fail with very low torque. Bolts that small I just palm them snug and a hair.
 
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Messages
1,946
Location
GA
I don't know what you did wrong but that should be an easy job to do; maybe somebody mess it up way before you? likely??
your inch/lbs look good on your torque wrench, within specification

also that torque wrench is more for something like tires not for 8mm screws id say

yet, you haven't screw it that bad, any shop or even yourself you can tap that out

btw, good looking engine on the inside

Tekton is doing great torque wrench for small jobs like that
IMG_1718.jpeg


looks like I got mine in 2015
IMG_1722.jpeg
 
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Messages
1,650
Location
TX, USA
84 in.lbs is only 7 ft.lbs. The 1/4" Torque wrench is usually on in.lbs while 3/8" is ft.lbs.

You need to use the 1/4" torque wrench in this case.
Start with half of 84 then moving up to 84 incrementally.
 
Messages
7,936
Location
MI
Oh man, as diyer I have been there/done that type of learning curve numerous times over my lifetime. Trust me, pros make mistakes sometimes also. I, too, have a tendency to kick myself when this stuff happens. In your case, I think I would follow Trav's advice and let a trusted mechanic fix it for you (at least remove broken bolts). Absorb your loss. Lick your wounds. Months from now the extra cost incurred will fade away. Get back on the horse, educate yourself more, and move forward.

My good example: Replacing the 4cyl. spark plugs for the first time on my last Caravan cost me about $150 and took a day. After fighting a glued on rubber plug boot for 1/2 hour, it finally released and my elbow jerked, breaking a plastic $120 MAF sensor. Lucky to find one at a dealer 60 miles away, a few hours later I completed the job.

You made many mistakes with the torque wrench. Never trust a borrowed one that you have no experience with. "Exercise"/practice with it on a small nut/bolt gripped in a vise. Lubing the threads made things worse. I would spend a lot of time on the internet studying how to use one - read mfg. manuals, faqs, and forums about their use. Many believe that using a precise tool automatically gives excellent results. Correct torque wrench use is not as easy as many think. Understand what errors (+/- values) can happen if not used correctly. Heck, most don't realize that torque wrench techniques have about +/- 28% error possibilities due to all the variables.

At my workplace some guys borrowed a 600 ft. lb. wrench and due to it's failure, they caused about $2,000 dollars damage to a commercial wood chipper while replacing the teeth. S it happens!

Thanks for sharing. These reminders help me........sometimes.
 
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Astro14

$100 Site Donor
Staff member
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Virginia Beach
Looks to me like you did it right, but I’ll bet that torque wrench is just a bit off. And that’s enough to snap the bolt.
From the look of it getting this out won’t be too bad. Because of the clearance underneath, you might even be able to continue to turn it clockwise and feed it out the bottom.

Generally, fasteners that break cleanly like that aren’t that tight in the threads. It should turn pretty easily. I once broke off a head bolt. Snapped it right off. Used the right torque specs for the engine, but the wrong year. Turns out the following year, the bolts were much larger. I was able to run the broken stub out of the iron block with just my fingers. So, don’t feel bad, we’ve all broken something, and this isn’t that bad...not compared with my mistake...

I like having consistent torque for this kind of thing. But you need clean threads, no oil. Just clean. If you use anti seize, or get some oil on them, then you just back off the torque 20%.

Might be time to invest in your own torque wrench. I recently bought this one in 1/4” for just such jobs.

Not cheap, but I am certain of its calibration.
 
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GMFan

Thread starter
Messages
2,092
Location
NC
your inch/lbs look good on your torque wrench, within specification

also that torque wrench is more for something like tires not for 8mm screws id say

yet, you haven't screw it that bad, any shop or even yourself you can tap that out

btw, good looking engine on the inside

Tekton is doing great torque wrench for small jobs like that
View attachment 39972

looks like I got mine in 2015
View attachment 39976
I have the exact Tekton torque wrench on order but shipment was delayed . And the only torque wrench I own does 20-100lbs, and I needed ~7ft-lbs . Hence why I borrowed my buddies in the next town over this morning.
 

GMFan

Thread starter
Messages
2,092
Location
NC
Oh man, as diyer I have been there/done that type of learning curve numerous times over my lifetime. Trust me, pros make mistakes sometimes also. I, too, have a tendency to kick myself when this stuff happens. In your case, I think I would follow Trav's advice and let a trusted mechanic fix it for you (at least remove broken bolts). Absorb your loss. Lick your wounds. Months from now the extra cost incurred will fade away. Get back on the horse, educate yourself more, and move forward.

My good example: Replacing the 4cyl. spark plugs for the first time on my last Caravan cost me about $150 and took a day. After fighting a glued on rubber plug boot for 1/2 hour, it finally released and my elbow jerked, breaking a plastic $120 MAF sensor. Lucky to find one at a dealer 60 miles away, a few hours later I completed the job.

You made many mistakes with the torque wrench. Never trust a borrowed one that you have no experience with. "Exercise"/practice with it on a small nut/bolt gripped in a vise. Lubing the threads made things worse. I would spend a lot of time on the internet studying how to use one - read mfg. manuals, faqs, and forums about their use. Many believe that using a precise tool automatically gives excellent results. Correct torque wrench use is not as easy as many think. Understand what errors (+/- values) can happen if not used correctly. Heck, most don't realize that torque wrench techniques have about +/- 28% error possibilities due to all the variables.

At my workplace some guys borrowed a 600 ft. lb. wrench and due to it's failure, they caused about $2,000 dollars damage to a commercial wood chipper while replacing the teeth. S it happens!

Thanks for sharing. These reminders help me........sometimes.
Thanks, appreciate it. Lessons learned for sure!

I dropped the car off tonight at my local mechanic and explained the issue in the note. Thankfully there are pros to bail me out. I don’t want to make it worse, that’s for sure!

I will definitely research more on the things to watch out when using torque wrenches and how to use one properly. Out of curiosity, in your opinion would a digital read out wrench have avoided this issue, or are there still the pitfalls you mentioned with a manual type?
 
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5,461
Location
Roanoke Virginia
Dang that really sucks. Luckily I’ve never had to deal with this yet. I’ve always used a 3/8 normal sized ratchet to tighten the bolts down never a torque wrench on a valve cover which if I did use one it would be 1/4 which I don’t own so I wouldn’t use one. I’d probably take it somewhere to have it done if you don’t feel comfortable doing it.
 
Messages
1,632
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.
 
Messages
1,946
Location
GA
I have the exact Tekton torque wrench on order but shipment was delayed . And the only torque wrench I own does 20-100lbs, and I needed ~7ft-lbs . Hence why I borrowed my buddies in the next town over this morning.
5D5C8CB5-D3F5-4317-9C60-B111F50677F5.jpeg


These your manufacturing specifications so that Tecton torque wrench is exact match for your job intended there; in fact, I’ve been thru that job before, done it on my old M6
 
Messages
7,936
Location
MI
Out of curiosity, in your opinion would a digital read out wrench have avoided this issue, or are there still the pitfalls you mentioned with a manual type?
To my knowledge, all consumer torque wrenches are subject to the variables that can result in +/- 28% error. That number comes from engineering forums and the variables include human error, fastener type, thread condition, wrench error +/-3%, and on and on.

I'm spoiled because I have available at my workplace a Snap On Techangle digital 1/4" inch lb. wrench. It's advantage (along with dial types) is that you can visually see the torque value as it increases vs. waiting for a click.

Still, on low torque cover gaskets it's a coin toss with cork/rubber/composite types. What I learned is that you can torque them to the spec. , i.e., 100 inch lbs.. If you go back again, it seems that the compressed gasket has relaxed and you can tighten it AGAIN to 10 inch lbs.. Before long, you've over squeezed the gasket and ruined it (ask me how I learned!). A better way might be to torque them equally to about half of the spec. with the torque wrench, then tighten them again with plain wrench, all equally 1/4 - 1/3 -1/2 turn.....whatever feels right. You can always tighten it a bit more if it leaks.

When I was shopping workplace torque wrenches, my OCD led me to talk with techs. at the mfg. for advice.....CDI/SnapOn, Precision Instruments, Sturdevant Richmont, Proto, etc... It's the BITOG way! No way am I any kind of expert on this stuff.
 
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