The next day I noticed a coolant pool on the floor at the rear of the engine - it had a slow leak!
Naturally a few swear words were expressed:
That meant I had to flush the coolant again, remove the QMax block, clean the surfaces again and re-install the bar****d!
I'd used a gasket instead of the supplied QMax sealant because the first time it took a long time to bolt it up to the rear of the block and I was pretty sure it had wiped off in many places as I clumsily tried to fit it and get the nut and bolt on and tightened.
A couple of other guys in a video install recommended this too which seemed reasonable - reading through to the end of their comments though, they too re-did the install because theirs leaked and they used the QMax supplied sealant the second time.
Big tip when installing the QMax block, USE THE QMAX SUPPLIED SEALANT, NOT A GASKET!
I removed the block and cleaned the surfaces again.
This time I bought an inspection camera from Hare&Forbes, https://www.machineryhouse.com.au/M697, so that I could actually see what the rear of the engine looked like and if I had any old gasket remaining.
The resolution isn't great, it's not bright enough and the unflexible camera at the tip of the flexible is too long so was nearly impossibly to get angled where I needed it.
The video can be rotated by 90* at a time so it makes it easy to manipulate a tool in your other hand, you can rotate the image so that your hand movements are natural (as opposed to needing to account for the camera's perspective which in this case was 90* from my view).
It was obvious from the inspection camera that there were in fact still patches of the original gasket remaining so over the next few weeknights I worked at removing them.
There were some areas I couldn't see so I popped into SuperCheap and bought this inspection camera:
https://www.supercheapauto.com.au/p/sca-sca-inspection-camera-4.3/563867.html
This one has a bigger and brighter display and the cable is more flexible so the camera can get into places the previous one can't.
Unfortunately the flexible camera cable isn't firm enough and if the camera or cable bumps anything, the camera gets re-oriented far too easily.
A cable with flexibility between this one and the previous one would be ideal.
This camera only allows 180* rotation so it's easier to get the camera aiming at what you need, find a firm resting place for the unit and orient the unit so that it makes manipulating your other tool more natural.
Because the camera is so small and the cable is very flexible, I was only just able to see the entire circumference at the rear of the head and saw a lot of original gasket around the lower stud.
The old gasket was removed over a few weeknights using a combination of razor blades, wet&dry fine-grade paper and a steel-wool scourer and way more patience than I've ever had.
I put a couple of old hard-drive magnets inside the engine to catch any steel wool fragments - worked well.
Other installers reported replacing the QMax-supplied rear bolt with an Allen-key bolt instead because it made it easier/faster to tighten (getting it to start threading is difficult and you can only turn a ring spanner about 1/4 turn at most).
I tried this before final installation (ie. installing the block without the sealant) and shortened the short-leg of an old Allen Key to allow it to fit back there.
Chamfering the Allen key's edges and rounding the corners slightly made it MUCH easier to insert the key and tighten the bolt.
I also chamfered the tip of the Allen bolt and made sure that it would start threading easily.
This 3rd time, I was able to get the block installed relatively quickly and after installing the rest of the coolant system it hasn't leaked for 24 hours.
down the allen key!
)
