Spring has, errr sprung...

[Dukedesmo]

Out of my engine, unfortunately!

Decided to service the Monster today, oil change, new rear tyre etc. getting ready for the spring.

Dropped the oil and found this on my sump plug;



A couple of bits of thin spring, around 1mm thick, 34mm long, obviously from some kind of oil seal. Now the only seals with springs of this size are the valve guide oil seals, aftermarket (AV&V) rather than OEM as the OEM don't have springs.

Some may recall that I had to replace the gearbox on this back in 2021 and whilst in there found the valve guides to be worn so replaced them at the same time. Rebuilt with new valve guide oil seals but luckily (being a bit of a hoarder), I kept the old seals as they basically looked fine and you never know...

Anyway, a quick check with an old seal shows that this is indeed a valve guide seal spring as you can see from this pic showing a couple of seals, one with the spring removed;



So now I've got to dive into the valve covers to find which one is missing a spring. Hopefully the seal is still in place and I can simply slip a spare spring over the end also don't know why it broke, especially into 2 pieces maybe just a case of **** happens?

Wish me luck.

[walkingpictures]

Good luck!!!

[Dukedesmo]

Thanks.

I started removing the valve covers, obviously there are 4 of them and you can probably guess how many I had to remove to find the missing spring?

Yes, thanks to Murphy/Sod, all 4 needed to come off. Turns out it's the vertical cylinder intake that's missing a spring.

No other apparent damage, the seal is still in place and, actually it's probably the easiest to get at as I can do it standing up over the bike but it was the worst to gain access to as I had to remove the tank, battery and battery box to get there.

I suppose it wouldn't do it any harm to leave it as is, no worse than the OEM seals? and that valve isn't sitting in a pool of oil like the horizontal exhaust does plus, I've no idea when it fell off but I'd rather it be right.

Here's hoping slipping a new spring over it is easy enough.

[Mr Gazza]

That's really weird, but well done for identifying it so quickly and finding the offending seal.
Possibly good that it was the vertical cylinder as a horizontal one would probably not have fallen down the drain hole? Or maybe that would have been better?

Have you measured the remains to be sure you've got it all?

[Dukedesmo]

Strange indeed, never seen such a failure before but the good news is that the seal looks fine and a new spring fitted though I doubt it would actually make much difference without a spring? other than maybe on the front cylinder exhaust where the oil pools around the valve.

The (complete) spring is a circle with OD of 12mm, ID 10mm, 1mm thick so call that 11mm overall length, in which case the circumference (C=2pi r) should be 34.56mm and I have 34mm so I'm saying it's all there or at least any remaining fragments are so small that they should get caught in the filter so I can't see it being a problem.

[stopintime]

I found my spring many years ago - didn't like it at all, but after some forum investigation identified it as you did. Replaced at next service. Good to know that they can find their way to the sump. Engine builder said that IF they got close enough to metal parts, gears and such, they would be "eaten" without damage to anything. Probably not 100% safe, but good enough for me.

[Dukedesmo]

Yes, I think I'd agree that the engine/gearbox could possibly 'eat' this kind of spring without too much bother and I would think that's how it broke into 2 pieces because after it had fallen down the rear cylinder oil drain it would have landed somewhere around the gear box.

That said I'd rather not use the gearbox as a 'waste disposal' unit (especially given I only replaced it a couple of years ago) but it shows (again) how useful a magnetic sump plug is.