I bought a 6 year old house, and the Previous Owners did basically zero maintenance.

The oven is a Bosch underbench electric unit, and it looks like the glass cap/protector for the interior light has broken off at some point, so they kept using the oven with the lamp exposed. The lamp does turn on when in use. I expect this has been left like this for at least 2 years, maybe up to 6 based on the condition of the rest of the oven.

This leads to a threadded glass ring welded into the fitting by dried/hardened food/oils, and looks like this:

enter image description here enter image description here

I've got the replacement cover already, and its essentially a very short glass jar with one thread around the top so I know this ring should unscrew conventionally.

I've tried blasting it with conventional oven cleaner to dissolve the shite, but its not getting into the threads.

I've tried some other solvents like "Contact 60" an electrical contact cleaner, and some other household liquid cleaners hoping they'd wick up the threads, but that's made no difference.

There's around 4mm of "neck" exposed so I can grip it with one hand and rotate, but the whole light fitting is loose, and I don't want to overstress whatever mountpoints are there. The glass is sharp too, so can't put too much pressure on it, even with a teatowel to hold it.

  • Do I have to open the oven and remove the whole light assembly, then work it on the bench?
  • Should I try to break the remaining glass with a hammer, or alternating heat and cold like cutting the neck off a beer bottle? Feels risky.
  • Or do I give up and get a service wallah out to do it?

Edit : Here's the new fitting, to show what the old one will be like:

New fitting

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    An old trick to remove a broken light bulb was to wedge a raw potato into the base of the bulb and rotate. But that doesn't solve your loose fitting issue. – bib Nov 27 '18 at 12:30
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    Be sure the light is off before sticking the potato in. :) If you go the route of breaking the glass, a hammer and a nail punch would work. Glasses and gloves first though. – Micah Montoya Nov 27 '18 at 13:09
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    There could be a silicone ring intended to keep cooking vapours away from the lamp. It will now be serving to make it difficult to turn the remaining glass. I think (and it's only my opinion) that it would be best to try gaining access to the back of the light fitting by disassembling the oven. Can you find any sort of service manual for it? – Andrew Morton Nov 27 '18 at 19:47
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    @AndrewMorton yes the manual is a user manual and simply says "unscrew and replace lamp" The brand new cover has no silicon gasket, so its unlikely to have one in there now (but not impossible) I think its just food grime baked in there. – Criggie Nov 27 '18 at 19:56
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    @Criggie Have you tried undoing it while the oven interior is still hot, so that the congealed grease is a little less viscous? Expect to accidentally burn yourself. If the lamp fitting is on the rear face of the oven, it might only need the removal of four or five screws to gain access (once you have got the oven out). – Andrew Morton Nov 27 '18 at 20:03

I have had some luck with a hot oven and needle nose pliers getting stuck fixtures apart, make sure to unplug prior to doing this, also I have found that sometimes turning clockwise (tighting) then back counter clockwise can help break loose whatever is causing the glass to stick. After tightening if it backs out a little then start going back and forth and usually they will come out. Worst case is a small punch to fracture the glass but this is my last resort.

  • I might try a cold oven (easier to work in) and heating with propane torch on the glass ring with needle nose as suggested. Keep in mind tho that heat expands, so this method could make it tighter, but you might be able to burn up some of the greasy gunk too. – Tyson Nov 27 '18 at 21:46
  • Good thinking - I'll start with a hot air gun. The oven should be rated for temperatures even when its coming from something else. – Criggie Nov 28 '18 at 0:52

Good news - it came off!

A Hot air gun was useless as was a butane torch - I suspect the heat was not softening anything and the adhesives were well and truely burned on. Perhaps spraying cold water on the hot glass might have helped crack it, but read on.

In the end I used a teatowel in one hand to cup the entire fitting and then pushed an "automatic punch" against the lip, and one piece cracked out on the first try. Against the other side, it took a dozen hits before breaking the same way, with a vertical crack and a chunk out.

enter image description here

I left the lamp in place to protect the socket from any damage. Its already got oil burned on the glass.

So then I could simply unscrew the remainder and it fell out in two pieces after one rotation, which I caught in the teatowel.

Not sure if it was the increased grip, or if it was the shock which broke the hold but it turned freely after that.

enter image description here

Despite using a damp catching cloth, there were heaps of tiny glass shards in the bottom of the oven. Had I attempted to use heat and cold to crack the glass, it could have made a bigger mess.

enter image description here

Careful cleanup is required here - glass fragments are no fun near food.

  • It would be nice to give credit to the answers and comments that suggested punches and heat by up voting those. – Ed Beal Nov 28 '18 at 3:53
  • @EdBeal fair point - done. – Criggie Nov 28 '18 at 5:56

I just had the same problem. My successful method was to warm the remaining glass and metal housing with a hairdryer, it took several goes to soften the grease etc. Then I had a small plastic tub of my granddaughters play-doh in a drawer which is around 2” diameter at the base and tapers towards the lid.

By inserting that inside the broken cover, pushing up and unscrewing it I was able to unscrew the threaded glass portion of the cover, hooray! Engineer call out had been quoted as £99 inc. vat plus any parts!

Hope this helps others.

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