Valve head cover bolt broke...

[neb4152]

Been worrying abouth this for several days... Was checking my valves for the first time at 7000 miles about a week ago. They were fine. Didn't think they would be out of spec but I love working on this scoot. Followed all instructions putting the head cover back on with gasket sealant and broke a bolt with my torque wrench. Had the wrench set correctly so I don't know what really was wrong. Was it the bolt? torque setting? Just to be safe I replaced all 4 bolts, although they were 2mm shorter than the ones I replaced. Set my wrench to 20 pound feet as specified. But...my wrench never indicated I had reached the specified torque and I stopped torquing before I broke another bolt. I felt I was well beyond 20lbft on all 4 bolts. I had tightened each with a regular socket wrench and then the torque wrench. Usually I reach a point in torquing and feel resistance and hear the indicative "click." Not on those 4 bolts. I don't understand. The wrench works. Used it yesterday for my clutch and variator. 100 miles since and no issues from underneath. Any concerns or advice for next time? Probably in 5000 miles. I guess the big question is should I check the torque again (and risk breaking a bolt?).

[Mel46]

One of the bolts is broken on my wife's PCX but it hasn't had any problems. Heck, it was broken back in 2013 but still no problems. I think we had the same situation. While torquing it to correct spec it snapped off. Don't worry about it if it doesn't leak. It might be that the spec is wrong.

[you you]

It’s a cover so if it’s not leaking it’s fine.

[springer1]

20 pound feet

I forget what the bolts look like, but they can't be much. They're just to hold a small valve cover on - no stress or load to that and threaded into aluminum or alloy as well.

http://www.portlandbolt.com/technical/b ... torque-gr2

[pcx888]

Just hand tighten. and 1/4 more. Thats all thats needed.

[gn2]

Broken bolts and stripped threads are why I stopped using a torque wrench.

[easyrider]

That torque spec is probably for new bolts.. Too many heat cycles on the old ones and fatique. I agree with above there are times when a torque wrench is not necessary and that is probably one.

[fish]

I never use a torque wrench for small fasteners, like cvt cover bolts, valve cover bolts, engine oil or gear oil drains, etc.
Fellow on Kymco forum stripped one of the 2 small studs holding exhaust to the engine. Pulled the stud right out of the head after installing new rear tire. He is a very particular & fussy owner, so used a torque wrench, of course. New tire became an expensive fix.
Working on aircooled VWs for decades....taught me the danger of torque wrenches on fasteners into alloy metals.
Just snug, with a small ratchet. It's a scooter, not a moon shot.
Breaking the bolt was lucky - could have stripped the head.
Fish

[homie]

Be tough to get after the remaining bolt with (easy out) at that angle in the limited space but it could be done. As for leaking oil, I think not. Not much pressure or oil moving under the rocker covers. Upper or lower bolt?

[you you]

It isnt a lbft, ftlb thing?

Use Nms like the rest of the civilised world

[springer1]

It isnt a lbft, ftlb thing?

Use Nms like the rest of the civilised world

Good thinking, might be. Anyways, small fasteners like that need small (length) wrenches, larger stuff like torque wrenches makes for too much leverage.

I also use anti-seize on almost everything. Especially when there's aluminum / alloy threads involved. It galls so easily, as does some stainless grades. Hell, I use it on spark plugs and even use it on wheel lug nuts. I bet 90% of owners who do their own wrenching never bought a tube of it, probably don't know what it is. When I got my (new) Stella years ago, first thing I did was go thru every fastener I could, backed them ALL off and re-installed with anti-seize. Even if they had lock nuts or nylocks, did them all. When I did BSA & Triumph restorations, I used it on every single fastener, even fender stays.

[easyrider]

It isnt a lbft, ftlb thing?

Use Nms like the rest of the civilised world

Good thinking, might be. Anyways, small fasteners like that need small (length) wrenches, larger stuff like torque wrenches makes for too much leverage.

I also use anti-seize on almost everything. Especially when there's aluminum / alloy threads involved. It galls so easily, as does some stainless grades. Hell, I use it on spark plugs and even use it on wheel lug nuts. I bet 90% of owners who do their own wrenching never bought a tube of it, probably don't know what it is. When I got my (new) Stella years ago, first thing I did was go thru every fastener I could, backed them ALL off and re-installed with anti-seize. Even if they had lock nuts or nylocks, did them all. When I did BSA & Triumph restorations, I used it on every single fastener, even fender stays.

Me too..although some say not to use on spark plugs threads,but I use it everywhere with great success..Many specs however say you cannot get a proper torque reading when using a lubricant ie lug nuts. I never had any problems however.

[BarryPCX]

It isnt a lbft, ftlb thing?

Use Nms like the rest of the civilised world

Good thinking, might be. Anyways, small fasteners like that need small (length) wrenches, larger stuff like torque wrenches makes for too much leverage.

I also use anti-seize on almost everything. Especially when there's aluminum / alloy threads involved. It galls so easily, as does some stainless grades. Hell, I use it on spark plugs and even use it on wheel lug nuts. I bet 90% of owners who do their own wrenching never bought a tube of it, probably don't know what it is. When I got my (new) Stella years ago, first thing I did was go thru every fastener I could, backed them ALL off and re-installed with anti-seize. Even if they had lock nuts or nylocks, did them all. When I did BSA & Triumph restorations, I used it on every single fastener, even fender stays.

You need to be a bit careful with this. The torque specifications tend to assume a 'dry' thread as far as I am aware. Lubrication can lead to over-tightening and potential breakage.

[aguim]

20 FOOT-POUNDS !!! Are you crazy ???

M6 valve cover bolts should be 8-9 foot-pounds, no more.

I think you misread the manual. 20 foot-pounds would be ok for M8 cylinder head bolts, not tiny valve
cover 6mm ones !

[you you]

20 FOOT-POUNDS !!! Are you crazy ???

M6 valve cover bolts should be 8-9 foot-pounds, no more.

I think you misread the manual. 20 foot-pounds would be ok for M8 cylinder head bolts, not tiny valve
cover 6mm ones !

Hurray

Everything isn't idiot proof. I feel alive.

[gn2]

Everything isn't idiot proof. I feel alive.

Every time man creates something "idiot proof" nature has a way of creating better idiots.

[you you]

Everything isn't idiot proof. I feel alive.

Every time man creates something "idiot proof" nature has a way of creating better idiots.

Witness the torque wrench

[Kristopshu]

Just a word of advice. With torque wrenches you need to be aware that they have a margin of error in both ways. Depending on a quality (and scale) its from 2 to even 8-10Nm for wrenches up to 150Nm. The bigger it is, the bigger the margin. So putting it against a worn bolt that requires 8Nm you can actually give her 50% more of its factory default. That's why if you don't need that kind of precission - don't do it. If you do - buy new, original bolts

[neb4152]

Thanks for all the replies. no problems since replacing the bolts. In a few thousand miles, I'll probably find those 4 new bolts are about to break. First time checking valves and I shouldn't have used the wrench. Those little bolts can't handle the big wrench and it isn't made for little bolts. I still use it on the variator and clutch and wheels, but only on the big bolts and nuts. The rest is torque gun or by hand.

[zroger73]

THANK GOODNESS I saw this thread before I reinstalled the cylinder head cover on my 2019 PCX follow a valve clearance inspection and adjustment at 631 miles. I'm "OCD" about doing things exactly per the instructions (including torque values). I was unable to find a torque specification specifically for the cylinder head cover. I was going to use 20 lb-ft based on the specified torque value for the "cylinder head nut". It did not occur to me at the time that "cylinder head nut" and "cylinder head cover bolt" were two different things (I should have known better - I guess the lack of a torque specification specifically for the cylinder head cover bolts was throwing me).

I tightened them to 10 lb-ft and even then my instinct told me that was a little too tight. While dropping off my 2019 PCX at the dealer this morning for warranty replacement of the factory IRC tires which were both out of round, I confirmed with the service manager that the correct torque value for the cylinder head cover bolts is 7 lb-ft (10 N-m, 1.0 kg-m).