Joined: Aug 2019 Posts: 1 Threads: 1
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Location: Northern Ireland
Car type: Austin Seven 1931
Could anyone kindly give me some advice, the little retaining set scew that holds the oil filler tube into the crank case sheared its head off on my 1931 Austin Seven yesterday. Can anybody tell.me what thread this is and give me any other advice on removing it, my oil filler tube is still held tight by the set screw minus its head ! When I remove the cap and look down the tube I can see what appears to be the set screw, am I right in assuming that the crank case is threaded and is there a hole in the tube on its neck where it fits into the crank case, any advice welcome or if I should leave it alone. thanks in advance. Alfie
Joined: Aug 2017 Posts: 781 Threads: 26
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Location: On a hill in Wiltshire
Yes, it is threaded, 1/4" Whitworth probably.
Leaving it means it could work its way in and drop into the sump on top of the oil gauze and have a short but eventful life being flung around by the crank.
I would start by drilling holes of increasing sizes, having worked some kind of plug on a string under it to catch the drillings, along with a strong magnet.
The old method of using the tang of a file, or the right sized screwdriver blade, forced into the hole should eventually unscrew it.
I would first get my big electric soldering iron on to it and leave it for a bit, to encourage it to loosen and discourage any Loctite that may have been used.
The worry is that it should never be so tight as to shear. If the thread is seriously damaged it will probably be engine out, better access, drill it out and helicoil back to standard or oversize threads.
Joined: Aug 2017 Posts: 952 Threads: 38
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If it broke off trying to undo it and it is still holding the tube I would leave it alone.
Trying to drill it out in situ will probably end in tears.
If you have a friendly TIG welder nearby get him to weld a washer to the broken bolt, then you can unscrew it, this method has not failed me yet.
Size is 1/4” Whitworth
Joined: Feb 2018 Posts: 80 Threads: 15
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Odd that it would shear but not the strangest thing that will ever happen on a Seven. Both above replies sound pretty good to me, with respect to Simon’s idea I’d suggest the magnet be augmented by a vacuum as nothing good will come from anything falling into the crankcase. It will be tight to get a normal drill in there so a right-angle drill might make things easier. You might need to sacrifice a drill bit and cut it so there’s only 10mm projection from the drill body, that will make it easier to get in to this tight spot.
If you can source it using a reverse drill bit would be a good idea, often just the heat generated by drilling combined with the reverse location is enough to get threads moving in the right direction.
Steve & Tate Davidson
Perpetual Amateur Austineers
Joined: Aug 2017 Posts: 628 Threads: 19
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Location: Sheffield South Yorks
Car type: 1932 RN saloon
You could make a plug from stiff upholsterer's foam, attached to a length of 6mm screwed rod with penny washers either side, drill out the screw remains as Simon says and then use a magnet to clean up the swarf.
Joined: Aug 2017 Posts: 3,391 Threads: 106
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Location: Darkest Bedfordshire
Is enough sticking through that it could potentially be gripped with something from the inside?
Joined: Aug 2017 Posts: 1,745 Threads: 42
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Location: Malvern, Victoria, Australia
If it was tight enough to pull of the head just leave the stub to hold the filler tube in place, which is all it does.
Joined: Aug 2017 Posts: 926 Threads: 22
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Location: Near Cambridge, UK
Car type: 1928 tourer (mag type), short chassis Gould Ulster
I have used a MIG welder to make a lump on the end of a little end bolt which had lost its head. I then used a small Mole wrench to remove the bolt, which enabled me to re-use the piston, but the connecting rod had cracked. Similar lump construction would be a lot easier in your situation.
Robert Leigh
Joined: Mar 2018 Posts: 45 Threads: 6
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Location: Maryland, USA
Car type: Austin Ruby ARQ LHD 1936
Just to add to the welding tricks... I have placed a small nut on the broken bolt/stud/tap and welded a puddle down the hole to the offending stuck thing. Even had luck with stuff broken off below grade. With a MIG, make sure the wire hits the stud first and fill up the nut. While red hot, hit it with a wax candle. Best if you get some fire. The hot wax gets drawn in to the threads. Wait a minute or two and wind it out. We made a few dollars on broken stud removals this way. Good luck !
Joined: Aug 2017 Posts: 952 Threads: 38
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Robert, we’re on the same page
