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-   -   Removing broken valve cover bolt (https://www.miataturbo.net/general-miata-chat-9/removing-broken-valve-cover-bolt-64437/)

falcon 03-22-2012 06:20 AM

Removing broken valve cover bolt
 
Sooo... stupidly back in September I overtightened a valve cover bolt and it snapped clean off into the head. There is nowhere to grab onto it as the break is level with the head. It's quite a small M10 bolt, so what would be the best way to get this out? Silly me decided to leave it when I left for Europe and now I just realized I need to fix that before I can get my car back on the road when I get back in April. :vash:

curly 03-22-2012 10:14 AM

I just did this a while ago. Apparently those bolts are meant to last 4,999 tightenings and not 5,000.

I was pissed that I had to remove the valve cover and buy yet another $23 valve cover gasket, however if yours is flush with the head I might either consider running without it if its in the center or taking it to a machinist. Feel free to use an easy-out at your own risk.

shuiend 03-22-2012 10:16 AM

How far in did it go? Any chance that there is some exposed below the lip on the head and you could unscrew it from below? If that is not a possibility I would probably just run without that one.

falcon 03-22-2012 10:22 AM

No it's not visible from the bottom. I did run without it for a bit before parking the car for the winter and it was weeping out of that area. I'm thinking to just drill it out and if need be throw a helicoil in. what a pain in the arse.

RattleTrap 03-22-2012 10:33 AM

Timesert...
http://www.timesert.com/

viperormiata 03-22-2012 11:56 AM

I did this last year. Luckily I had enough exposed when I took the valve cover off that I was able to grab it with a pair of needle nose pliers and twist it out.

I scrapped all the stock bolts and just brought grade 8 ones at the hardware store.

falcon 03-22-2012 11:57 AM

Yeah, the ironic thing is... I was running ARP bolts on all of them but had lost one when I changed my valve cover gasket. I put one of the stockers in, and right as it was getting tight it just gave way. I'm thinking I may replace them all with a stud/nut combo.

Wildanimal 03-23-2012 02:38 AM

Weld a nut to the top of the broken bolt. Owning a welder is the key to this fix though.

Bryce 03-23-2012 02:41 AM

<- This tool worked wonders on my oil pump housing screws.

flounder 03-24-2012 09:40 AM

Drill into the center of the bolt with a tiny left cutting drill bit and use an extractor. It should come right out and leave the threads undamaged if you don't fack it up.

Make sure you cover the head so no metal shavings end up in the bearings.

rleete 03-24-2012 01:34 PM

Aren't all the head cover bolths through holes? Just get a drill smaller than the threads, and drill it out. Hopefully, the drill will catch, and drive the broken screw right out the bottom. If not, you can now drive a drywalll screw into the hole and thread it on through.

triple88a 03-24-2012 06:12 PM

You can always try cutting a flat on the bolt and turning it out with a screw driver.

Stein 03-24-2012 10:46 PM


Originally Posted by triple88a (Post 853221)
You can always try cutting a flat on the bolt and turning it out with a screw driver.

This. If you get a fine cutoff wheel on a dremel, even if you cut into the flange a little bit on either side of the broken bolt you will be able to slot it enough to get a screwdriver in there. You will likely find that it isn't tight in there at all.

Before doing that you might just try picking it backwards with a dental pick.

Brave777 11-14-2014 07:17 PM


Originally Posted by Stein (Post 853291)
This. If you get a fine cutoff wheel on a dremel, even if you cut into the flange a little bit on either side of the broken bolt you will be able to slot it enough to get a screwdriver in there. You will likely find that it isn't tight in there at all.

Before doing that you might just try picking it backwards with a dental pick.

Holy crap this is gold! Pure simplistic genius. Thanks! :party: (Also holy thread revival!!)


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