What's my oil filter bolt got inside it?

[Ashdowner]

Can't really see it very well here but the second hole from the right of the oil filter bolt is blocked by a piece of cylindrical metal (brass?) which has a spring below it (to the open end of the bolt) and this is held in place by a pin (small hole 2nd picture) going through the bolt. My question is what the hell is it? Also the holes in the bolt have all got bits of metal scarf as if the hole doesn't seem to have been finished of properly. Anyone else got the same?. 

[hairygit]

Oil filter pressure relief/bypass valve. If the oil filter becomes badly clogged, the pressure forces oil through the valve to provide unfiltered oil to the crank etc to avoid totally destroying the engine.

[Ashdowner]

Thanks hairygit. My oil change discipline is pretty good so I hope it never comes to that.

[Bryanj]

The technical term for the internals is "Gubbins"

[steff750]

Oil filter pressure relief/bypass valve. If the oil filter becomes badly clogged, the pressure forces oil through the valve to provide unfiltered oil to the crank etc to avoid totally destroying the engine.

yes and the unfiltered oil tends to take bits of crap that has been sitting there with it through the bypass valve ,so you might  still have a engine that is toast?

[hairygit]

Oil filter pressure relief/bypass valve. If the oil filter becomes badly clogged, the pressure forces oil through the valve to provide unfiltered oil to the crank etc to avoid totally destroying the engine.

yes and the unfiltered oil tends to take bits of crap that has been sitting there with it through the bypass valve ,so you might  still have a engine that is toast?

Indeed that may happen and the shells get knackered, but easier to fix than a seizure with shells spinning in the cases!

[mike the bike]

I thought they couldn't do that because of the cut outs / flat bit / whatever the proper name is.

[martin_uk]

I thought they couldn't do that because of the cut outs / flat bit / whatever the proper name is.

The tabs are just to accurately locate.

The shells are a "nip fit" in case/con rod, but if sufficient force applied due to seizure between bearing surface and crank journal, will rotate.

[hairygit]

And if they do spin, there's a chance they'll knacker the crankcases!

[Bryanj]

Thats not a chance its a certanty

[Ashdowner]

Wish I hadn't asked. I can't sleep at might now for worrying. Think I'll change my oil once a day.

[Ashdowner]

Well my pressure relief valve wouldn't have worked at all because the holes in the bolt had scarf attached to them which had locked the piston solid - and it wasn't crap that had got there, it was crap that I had to physically part from the bolt itself because it had been left there from the manufactiure.