Update:
She's not been my daily driver for a few weeks as the engine mounts properly 'bottomed out'. I've been 'planning' to sort them out for ages so this weekend I got on with it at last.
There is mixed information about filling 360 engine mounts with Sikaflex so I thought others might be interested in my 'experience'.
Won't cover removing the mounts - Haynes manual typre stuff & pretty easy, although we
did find it necessary to remove the mount-to-body brackets despite it being said elsewhere on these boards that just lowering the engine frees the 'canisters' for removal!
Exactly how to drain & re-fill the 'canisters' is the least clear thing about all this. Little bro has more hands-on experience of bodgi... sorry, FIXING cars than me so we had a few discussions ...
Levering out the ball-bearing 'valves' allows some of the old liquid to drain. A lot of shaking, standing, then shaking again is needed to get it all out though. Spraying brake cleaner in, then forcing air in from a compressor (which blasts everything out when 'released') seemed to help - mind your eyes!
Going on reports that there are 2 chambers inside each 'canister' I gambled & drilled a hole about half-way up the sidewall 'opposite' the valve. This went through two metal layers & into a 'rubber bag'. Forcing air into this new hole pushed the relevant threaded attachment out & excess air through original 'valve' appature; proving I would be putting Sikaflex where liquid was before.
We altered our approach as we went along but have concluded the best way to refill is through the original 'valve' apperture. Eventually the Sikaflex makes it's way through the two chambers & excess comes out of the newly drilled hole.
Following advice in other discussion we also drilled into each of the 'castellations' on one end of the mounts. This stops the 'rubber bag' expanding. I reasoned that this sealant is in compression (where it should be happier) so there will still be some resistance if the stuff in the 'bag' (being in tension) fails in some way ... & the mount will still have some effect...
A pictures paints etc...
Circled in red to the left is the original "ball bearing valve" hole
Circled in red to the right is the new hole I drilled
Circled in green are the holes to 'pack' the canister & limit expansion of the 'bag'
NOTE: There is only
just enough sealant in a 300ml tube to do the two mounts. In fact I had to use a small amount of another sealing product because I wasted some Sikaflex after a bit of an error
(as Sikaflex is specifically named for filling, I mixed this in where it seemed less critical ie as 'padding' between rubber bag & metal outer).
As long as you don't go overboard on the first mount, one of these should do the job...
The mounts are compressed in a vice as we speak to be re-fitted after at least a week as recommended by others. I will let you know how they perform once they have been back on for a few miles...