Just checked my oii and it needs topping up.

Tried to undo the filler cap and found the whole filler tube spinning in the rocker cover.

Is the tube screwed/clipped in or is it supposed to be part of the rocker cover?

I'll have to find something to hold the tube still so I can undo the cap now.

the tube just unscrews. Mine sometimes does it. Just unscrew the whole lot, then when it's out undo the cap. Alternatively, get some mole grips or eagle beaks to hold tube whilst you undo the cap.

Mine does that too. Sometimes wrapping a rag round the tube when holding with one hand gives enough grip to remove the cap. Otherwise I use one of those Boa Constrictor rubber strap wrench thingies to hold it. Works fine.

Those Boa Constrictors are expensive for what they are but occasionally the only thing that will get you out of trouble without unacceptable marking or other damage to whatever you are holding. I've got three, full size, baby and an even smaller unbranded beast, probably out of Poundland / Poundshop or similar, intended for bottle and jar opening. Funnily enough the unbranded one has teeth on the back of the belt which logically ought to give a stronger pull whilst the Boas are just a plain band.

Rag underneath trick for extra friction helps if something is really stubborn. Tried too hard once and broke the strap on Baby Boa. Which got fixed as tightwad 'ere wasn't splashing out that much on a new one!

Clive

There should be two lugs inside the tube so you can turn or hold it in relation to the filler. Mine came right out when I did an oil change before setting off for France last weekend and I found that my pliers were a decent fit inside so used them to screw it back in after I'd got the cap off.

Mine does the same thing! Used strap wrench to put it back as hadn't noticed Gilbertd's lugs!
Would probably put a bit of Loctite on it, if I could be bothered...

Or don't tighten the cap too much, they don't come loose easy (plastic on plastic).
I used a leather straptool for oilfilters to undo the cap and fitted a large O ring between cap and neck.

I've never noticed the lugs before and have used a strap wrench on the odd time it decided to try to come loose. It was only this time that I unscrewed it completely and noticed them while trying to work out how to grip it to remove the cap.

Same here. It's obviously a factory fitted feature!

Same issue only maybe worse on the Jag engine'd L322s.

Age related problem. Umpteen hot to cold thermal cycles on a large, shallow, thread in aluminium alloy will eventually loosen it. Doesn't help that there is a temperature gradient along the thread too.

Aluminium alloys do funny things when it comes to stress and thermal cycling. Something the designers have to be well aware of when choosing materials for seriously designed things. Sort of thing that bites you on the ass several years down the line when, as with rocker covers, only basic design like cheap, casts well and can be painted are considered.

Alloy wheels still worry me as fatigue life of the materials used is both finite and seriously shortened if the folk who make them don't do it right. Gawd knows what effect back street repairs have. Nice fat P38 tyres mean such is probably no worry for us but the modern rubber band tyred breed suffer badly when kerbed and I'm certain that many are repaired when they should have been scrapped.

Clive

Agree totally on alloy wheels. Other half has a 2004 Merc and one of the tyres kept losing pressure so I took it in to get the rim cleaned off and sealed. They dunked it in a water bath only to find it was leaking from a 2 inch long crack on the inside of the wheel. No sign of it having been kerbed and it runs 65 section tyres too so not the low profile ones a lot of cars run these days. I was able to find a replacement matching wheel on eBay as I wasn't keen on he idea of getting it repaired, I've seen some repairs in the past that I wouldn't trust.

I’ve found they normally come unscrewed when the foam has worn and they grip each other, I cut a new ring out of memory foam, just finger tight now holds it tight enough to not come undone

no10chris, is this foam inside the filler cap or between the rocker cover and the tube?

I didn't do the cap up unusually tight last time, not sure why it's chosen this time to seize. I tried it again once it had all warmed up but it's still not going anyway.

The repair will need to wait until the weekend - it's a bit cold to have the baby out on the driveway while I do it and mummy will be home from work at the weekend.

I take it you've started you paternity leave then?

Yep - no more work for me until May!

The sponge is in the cap, it squished down over the years, then without knowing your cap locks on, come across more than a few of them, lol