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Does anyone have any advice on how to remove this stripped aluminum bolt?
I can't find a socket that will fit, an E8 torx is the correct socket for this bolt but that is too big now. Have tried various smaller torx and hex sockets, nothing fits once torque is applied to the wrench, the socket easily slips off.
It's fastening the ignition coil for cylinder #8 on my M157, right at the very back close to the firewall, so I can't really 'push' against the socket to get any purchase.
I don't care about damaging the bolt or coil, they'll be replaced.
The bolt extractor is your best bet. They're designed to bite/grip increasingly with increasing ccw torque. Pliers or visegrips can sometimes work, but usually damage the bolt and lessen the efficacy of a bolt extractor.
Yup, bolt extractor looks like the only way to go here as too much metal is missing. The sharp teeth will dig in, create their own connection and give you a good grip. Might be a good idea to review the tool that did this to determine if it is worn out and should be discarded (or at least put in a dark space in the tool box for those "special" uses where you don't care about whether it survives).
Just an afterthought, have you considered using those sacrificial pigtails on your coils' wiring harnesses that help stop oil wicking into your ignition wiring harness and destroying other $tuff? A cheap method of protection in case there's an oil leak or seepage.
Yup, bolt extractor looks like the only way to go here as too much metal is missing. The sharp teeth will dig in, create their own connection and give you a good grip. Might be a good idea to review the tool that did this to determine if it is worn out and should be discarded (or at least put in a dark space in the tool box for those "special" uses where you don't care about whether it survives).
Just an afterthought, have you considered using those sacrificial pigtails on your coils' wiring harnesses that help stop oil wicking into your ignition wiring harness and destroying other $tuff? A cheap method of protection in case there's an oil leak or seepage.
Thanks, good idea about the pigtails, I have them on my cam magnets. Not sure pigtails would fit nicely under the foam insulation that sits on top of the injectors/coils though. There was no sign of oil contamination in the coil connectors I checked.
So, about the bolt extractors, the set I bought only went as low as 8mm, that's too big for an E8 bolt. Think a 6mm bolt extractor will work. Will report back.
Tried a 6mm bolt extractor.. this did a great job at rounding off what remained of the edges.
Then tried jb welding a socket to the bolt, unfortunately the jb weld was fantastic at bonding to the socket but only barely bonded to the head and base of the bolt. I tried a second socket, but with additional jb weld applied, with the same result (I waited over 24 hrs to allow the jb weld to cure etc).
@JettaRed those pliers look interesting, might order those now, thanks.
Otherwise I'm planning to let my mechanic take a look when the ML is due an oil change later in the year. There is no rush as I was only completing this job (new plugs/coils) as preventative maintenance.
Does anyone have any advice on how to remove this stripped aluminum bolt?
I can't find a socket that will fit, an E8 torx is the correct socket for this bolt but that is too big now. Have tried various smaller torx and hex sockets, nothing fits once torque is applied to the wrench, the socket easily slips off.
It's fastening the ignition coil for cylinder #8 on my M157, right at the very back close to the firewall, so I can't really 'push' against the socket to get any purchase.
I don't care about damaging the bolt or coil, they'll be replaced.
Thanks
Small pair of good vice grips should get that out. But what I would do is take a cut off wheel and cut a slice in the top of the bolt. Use a good flat head screwdriver with that has the machined part below the handle to put a wrench on it. Or one of this impact drivers you hold tension on and wack with a hammer. Just don’t smash it too hard and crack the valve cover.
The bolt's fluted cap likely compromised the efficacy of the 6mm extractor's grip. With the flutes gone, a smaller size extractor might do the job. Harbor Freight has a set of bolt/stud extractors (its Icon brand) for $60, but letting your mechanic deal with it might be your best alternative, as it might require drilling and a stud extractor. I often wonder how the design engineers choose fasteners for each application. I changed the oil in my BMW yesterday. The drain plug is an 8mm hex key and the filter cannister drain plug is a T55 -- no reason both could not be one or the other.
06-18-2024, 04:03 AM
