Torque wrench broke head bolt. This sucks.

[Lzybmbjj30]

I set the torque to 20 lbs on the first go around. I wasn't able to pull the wrench in on smooth turn because of the damn hood in the way so I kept having to reposition it on the bolt. It worked on the 20 lbs setting but seemed to not want to click on the 30 lb setting on the 2nd go around. It felt like I was pulling with more to hand 32 lbs and then the bolt snapped. Luckily I was able to unscrew the broken ends from the block but now I have to replace the brand new head gasket.

Is there some reason the torque wrench isn't clicking at the right poundage?

 

[North Idaho Wolfman]

Did you oil the threads of the bolts?


Put the torque wrench on a bigger solid bolt and try to see if it clicks, if not you'll need to replace it.

 

[1970cs]

Another tip is to run a tap into each hole and used compressed air to blow the debris. Also a small amount oil or spray lube under the head of the bolt will help.

Pat

 

[Lzybmbjj30]

yes I put oil on the bolts but it's possible that the wrench wasn't calibrated properly.

 

[armylifer]

Another thing to consider is whether you were using a socket extension or not. Or, if you were using a swivel joint on the wrench, that could also affect the torque applied. Most torque wrenches that I have used are most accurate when used straight on a bolt head without an extension.

 

[Tooljunkie]

If the head gasket wasnt compressed with bolts to full torque value and its not scored or damaged i see no reason you cannot carry on with it.
Best results with clean bolt threads and block holes.
So this torque wrenc doesent ratchet? Go find a better one. I own 5 torque wrenches,all for different circumstances.

 

[Lzybmbjj30]

I have the old head bolts and 11 of the new ones. I think I need to replace the gasket as generic of ring seems to have compressed and pressed the gasket hole around it wider than it was. It's hard to explain. Also the old bolts I don't remember what holes they were screwed into. Do I need to replace all the screws? Does anyone know if the d722 uses torque to yeild?

 

[Wild and Free]

Torque wrenches need to be calibrated fairly regular, We have all of ours done once a year, when I was still pulling wrenches for a living most all shops paid to have all the mechanic torque wrenches calibrated yearly. I am lucky we have a calibration shop right in town close to me and also the mine I work for has other tools jobbers who do it as well for us.
In need to have my personal ones done again here soon too.
One ag shop i worked at had holes stripped out of a block on an engine overhaul that started the wrench calibration regiment, was a lot cheaper to have it done than to repair a block.
Today things are way more critical than the days of old for using a cheap old torque wrench not knowing if its calibrated or not.
Lots of softer metals like aluminum and specialty alloys now that need very strict torques and then the miss matched metals like cast to aluminum and the need for precise torques becomes even more critical as does the need for use of the correct fasteners for the different alloys and metals that expand and contract at different rates makes ones head spin.
Here is the local to me calibration shop.

http://www.teamtorque.com/

 

[Southernfarm]

I agree with Tooljunnkie, if you haven't torqued the bolts to full spec, your gasket should be fine. I was given this hint from a mechanic for small aluminum car engines. Get some cheap aluminum (color) spray paint. It contains small amounts of aluminum. Spray both sides of the head gasket and put on the engine and bolt it down. The aluminum will spread around and melt into the tiny holes. I have no proof for this for Kubotas, nor have I used it for that, feel free to comment or shoot this down.

 

[cerlawson]

There are old fashoned torque wrenches that have a pointer and a metal numbered plate near the handle. If you can borrow one and compare results that may help you. There are other ways, such as with a spring scale that you can rig up. I'd check the accuracy of the wrench first.

 

[Wild and Free]

Like previous poster mentioned the dial / needle pointer torque wrenches require no calibration they are either good or bad but one needs to take the torque reading as a "General Guideline" for the range of torque they give for any given fastener and not an exact for critical stuff.

 

[North Idaho Wolfman]

I would normally say you could reuse the gasket, but the fact that you were able to tighten one down to the point of breaking makes me think it's possible that you have squashed it a little too much, safer to just replace it.

An no that kubota engine does not use torque to yeild, that's normally used on soft metals like aluminum blocks.

 

[adventure bob]

Torque wrenches, regardless of whether they are a click, or beam need calibration. beam torque wrenches do get out of whack due to rough handling and age. An extension or socket that is in line with the rotational axis of the torque wrench has negligible bearing on the torque applied. Now a crows foot or an offset adapter has to be accounted for in your torque calculation.

http://www.engineersedge.com/manufacturing_spec/torque_wrench_1.htm

or

https://www.belknaptools.com/support-library/extensions-calculator/

This has the basic principle and math it your using an offset adapter. If your just using a straight extension and a socket the moment arm of the torque wrench isn't changed and thus no corrective math is needed.

 

[Creature Meadow]

My profession has been calibration for the last 18 years and I often calibrate torque wrenches.

I have found dial type to be more reliable the click type. I find the click type out of tolerance much more often than dial.

Most all manufacturer's recommend an annual verification/calibration of their torque wrenches.

Many torque wrenches have a tolerance of +/- 6% full scale, some of the top brands will be in the 2% to 3%

I also calibrate in both directions, clockwise and counter clockwise.

If you have a dial torque wrench tighten a bolt to the desired torque then use your suspect wrench and see if it clicks at your desired torque you just tightened.

Hope this helps.

Also you have both inch and foot pound torque wrenches, verify you are using correct one.

Jay

 

[Wild and Free]

I would normally say you could reuse the gasket, but the fact that you were able to tighten one down to the point of breaking makes me think it's possible that you have squashed it a little too much, safer to just replace it.

An no that kubota engine does not use torque to yeild, that's normally used on soft metals like aluminum blocks. ;)

I agree with the blueish text above.

I disagree with the text in red, I work on heavy equipment and almost all we torque is torque to yield anymore. Most things want a loaded torque in a way so there is a stretch put on the fasteners causing it to clamp more consistently. This is where one needs to follow the recommended torque procedures of whatever one is working on, heck on our Cat equipment they even switch back and forth so one needs to stay on top of the part# and service procedure changes as time goes.
I do agree that things don't change much on the small stuff here on the Kubota stuff so following the service manual is best.
Heck even working on Cummins they have switched back and forth several times over the years on head bolts from static torque to torque to yield but when one gets an OEM bolt kit it has directions on the procedure to use for said fasteners.

 

[Lzybmbjj30]

So how to I calibrate it if it's off? Do I need to take it somewhere? Also it's brand new. It wasn't the most expensive but I would think it would be pre packaged as calibrated.

 

[Tooljunkie]

Snap on dealer calibrates right on the truck. Click type are usually good for 1,000 clicks before needing re calibration.

Im suprised you broke a bolt. Unless it was corroded,or previously stressed and cracked. Would have to see the break to verify.

Had a ford supercoupe (3.8 supercharged) that used torque to yield bolts. Cleaned,chased threads and lubed as manual described, twisted 5 NEW bolts before i quit and reused old bolts.check for necking (narrow spot on threads with straight edge) and twisting (roll on a flat surface to look for wobble)

No necking or twisted/bent bolts should be good to reuse.

 

[Wild and Free]

So how to I calibrate it if it's off? Do I need to take it somewhere? Also it's brand new. It wasn't the most expensive but I would think it would be pre packaged as calibrated.

Any quality wrench comes with a certificate of calibration testing results if it was calibrated before selling, most common brands i have seen have this with them in the case for the last 10 years or so.

I posted a link to a reputable calibration company in one of my previous threads, check around there may be others more local to you.

http://www.teamtorque.com/

 

[RCW]

So how to I calibrate it if it's off? Do I need to take it somewhere? Also it's brand new. It wasn't the most expensive but I would think it would be pre packaged as calibrated.

I have no idea the size/brand of torque wrench used, but found with mine if working at the lower limit of the wrench you can't hear the "click". You can feel it more than hear it. Don't ask how I learned that many years ago......

If it goes down to 20 or 30 ft/lbs, not sure I could hear my 1/2" drive at all, but can just feel it.

Now I have 5 torques, 3 are simple Harbor Freight at $12 each on sale. I try to use a torque wrench whose mid-range is for the stuff I'm trying to fasten.

I've figured out ft./lbs to in./lbs for low-torque stuff, and used a smaller/better wrench before, just to be safe.

Just a thought from a similar, bad experience. Been there, done that, so I know your pain.

I'm not re-building engines everyday, so my click-type work, but there are more accurate options.

Good luck!

 

[Lzybmbjj30]

I'm guessing there was a calibration issue but I'm also thinking it had to do with the fact that when I torqued the bolts they weren't done in one smith turn. The hood was in the way and I should've removed it first. I would twist the bolt incrementally and then have to put it back on the bolt head to twist it and reset several times for it to click. I'm thinking that this threw it off somehow. The first turns I set it to 20 lbs. When I set it to 32 lbs it snapped the new bolts before it clicked.