Help with broken bolt , torqued correctly?

Well, last night, I decided to do another complete oil change with nothing different to the usual. When I tightened the oil hose bolt (2) in the picture to 10 Nm / 7.2 ft·lb

oil_11.jpg

However, things didn't get to 10Nm, before the bolt snapped. Thankfully, I didn't strip the thread on the case. Now my question - I believe my torque wrench to be working just fine (precision instruments model only months old with not much use). I did not clean the bolt of old oil. Could the engine oil have resulted in a faulty torque reading much lower than normal, or did I get it wrong and the torque setting should be lower for this bolt? Don't want to break another, or risk something worse :thumbsup:

Also - any ideas on what the replacement size/thread is?

The bolt holding that oil line in place is a 6mm x 1.0 thread pitch. Your torque spec sounds right at 7.2 ftlb. You really need an inch pound torque wrench to get down this low (86 inlb). That'll get you a more accurate reading. That's not very tight, but it's not a big bolt!

Just tried around to get a replacement - no luck at local Yamaha dealer :awww:, but thought what the heck, I'll try Honda - thanks to the boys in red :thumbsup:, I'm back in business. Total cost $0.00 :devil:

I also broke a bolt a couple of weeks ago changing the oil except it was the long bolt on the top right side of the filter cover. Never could get it out since it broke off about 2-2 1/2 inches inside the motor. Tried tapping it and that still didn't work so I finally got a heli-coil and fixed it. Thats the last time I will ever tighten a bolt without a torque wrench. My wrench is in ft. lbs only so I just set it about 1 lb. lighter until I can get a wrench in inch lbs.

Well, can't say I wasn't nervous tightening up the new bolt. Also set it slightly under 10Nm. I spent $180 on an excellent dial torque wrench from Precision Instruments (0-20Nm) with 2% accuracy in April this year, so I don't think calibration was an issue here (or it had $!#&* better not be). Luck was on my side, and I could get it out with a pair of pliers - otherwise it would have been hell.

Decided to flush my radiator and refill with Engine Ice (gotta love the blue color!) - well, as if it hadn't been a bad day already, but I had not put the dipstick back in. Well, if I didn't splash some fresh hose water down my oil filler :thumbsup:. Oh well, gave me a chance to check all my bolts torque settings again :devil: - dumbass me

I belive I have broken that bolt off, but just at the way end. I did not use a torque wrench though..

There's some bolts on the machine that just don't need to be torqued as specified. Use good judgement, and go by feel. Little bolts with 8 or 10mm heads do fine with "hand torque-ing". I only torque the larger nuts like stem nuts, axles, etc. The manuals say to torque everything for liability's sake. Anything with an aluminum or copper washer should not be tightened down enough to squish the washer either. Especially drain bolts! :thumbsup:

Man...you don't need to use a torque wrench on those bolts, and they don't need to be gorilla tight either. These bolts can easily be torqued by hand and by feel with a 1/4 " ratchet and socket. Think about what you are doing....the bolt only needs to be tight enough to compress the oring and seat the oil filter cover down fully. The same goes for the oil lines.

If you have a low quality or faulty torques wrench, you will not have the "feel" opf how tight it is through the longer handle. You could risk snapping them off. On cam caps and engine internals...always torque. But these bolts...just use common sense.

I've had a problem with twisting off oil filter cover bolts. One was the long one on top and it broke off way down inside the hole. The bolts I broke looked crystalized where they broke. I use a torque wrench and they twisted off way before they were tight enough to do their job. I've been told the bolts stretch rather quickly and need replaced. I've decided the way to go is to replace those small bolts before they have a chance to break. They aren't expensive and it is cheap insurance. I'd rather spend $1.50 than spend 8 hours trying to get a broken bolt out.

It's possibe that the bolt was damaged for a fall :thumbsup: . 10NM wont break a M6 bolt thats in good condition. Even if the thread was damaged the torque wrench would still click off long before the bolt should have broken. The only bolts I torque on my bike are the the head bolts. If you are a complete mechanical newbee , maybe you should torque all bolts for a while 'till you get the 'feel' for whats right.

I also broke off one of the bolts on the oil filter cover. I was lucky and was able to unscrew the broken portion with pliers. I don't torque anything on aluminum anymore. Just tighten it down to where it feels secure and it should be good. You could check it before every ride to make sure there are no leaks if you'd like. After a while you'll start to trust your judgement on how much to tighten bolts.

You're right on this one. Normally, I'd just tighten things up until they feel right, but I had some time and decided I'd 'do it by the book' - well stupid me, it felt 'wrong' using the wrench, so I removed the bolt, checked it for unusual wear couldn't see any, so went about tightening. Next time, I'll go back to using feel....and replacing all of the bolts with new ones, just incase

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