My morning started out checking the valve clearance on my just acquired generator with a Honda GX270. Inside was great and clean, clearances passed with flying colors and it all went downhill when I put the cover back on. Couldn’t find the actual spec, other than 27 ft Ib of torque at standard torque valves for 10 mm bolt. I thought it might be too much so I used a torque wrench to take off to see how high it goes. I thought I settle at 15 and here I am, a broken bolt.
Broken valve cover on Honda GX270
- Thread starter NH73
- Start date
Bolts are measured by the thread not the socket size! You have a 6 mm bolt.
I didn't think about the smaller thread size over the bolt size. Yeah, now I know and even after I thought I would do it less. Of course now, that puts your standard torque valves at 7 ft.-Ib. I case anyone wants to know it broke around 11-12 ft.Ib.of torque. Yeah, I know I am a novice. Should I now go buy a new cover and gasket?
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Yes.
The cover is most likely distorted/warped by that torque and it will be difficult to get it to seal properly.
Once you extract the broken one, snug is good enough.
Sometimes by "feel" is all you need and certain torque specs are just to have one.
If it leaks don't keep tightening replace the valve cover a used one is good enough or double gasket and pray!
15 in/lbs is awfully low - just over a ft/lb. I would expect it to be as low as 60 to as high as 90 inch/lbs
Were you able to extract the bolt ok?
Yes, it got done on Friday. Co-worker did it for me. He told me it was one of his easiest extractions he ever done. So much when he drilled the hole, it went in more. He told me the offset in the bolt would have prevented things from getting worse. It wouldn't smash the cover, like some have suggested here. So got her back together, put new spark plug and air filter in. Then got 2 oz. of Mechanic in a bottle to a gallon of gas. Ran it for 15 minutes. Ran fine on half choke and rough with it off.
I tighten these types of things by feel.
Mee too - don't have or need a torque wrench that goes below 20 foot-pounds.
I find that a lot with small bolts. Torque causes more issues than just using a 1/4” ratchet unless you have a calibrated low torque snap on torque wrench. I’ve built 2 stroke race motors turning 10,000 rpms and the small fasteners I just go by feel. Even race mechanics told me the same. “Just tighten them, don’t overthink or overdo it” case/ head bolts is different.
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