After seeing BrilliantBlackBirdy’s install of the DaveFab aluminium header tank from Moss, I gave in to temptation, especially since I know the old plastic one in my NC is original and now eleven years old.
Fitting it was simple, and not a drop of FL22 spilled, provided one remembers a few simple cheats. I also made up some poly-washers from some 1mm sheet I had, to allow that smidgeon of movement with the thermal cycling, and to protect the paint on the cross-member.
The instructions supplied with the tank are basic and will do, but I added a couple of obvious cheats.
Preparation.
I checked the spigots on the new tank for burrs and sharp edges, and smoothed them off with some fine emery.
I then checked the new tank was clean and flushed it out with boiling hot water a few times.
I checked the pressure cap really does fit as claimed (been stung before a few years back with an exchange rad.)
Made poly-washers to sandwich the new tank mounting flanges, easy with magic marker, strong scissors and a leather punch.
Removing the old tank.
Make sure it is all cold and no pressure in the system. Replace the pressure cap fully done-up on the tank.
Remove the battery cover, to improve access.
Use a vise-grip to release the two top hose clamps and move them along the hoses past the end of the spigots.
Pull the hoses off; gentle wiggling/rotating with the vise-grip breaks the seal and makes it easy.
Plug each of those small hose with a 3/8" (ish) drill shank and tie them back out of the way.
Plug their spigots on the old tank tightly with some screwed up paper to prevent later spillage.
Undo the three nuts holding the tank, AND the fourth nut holding the support bracket.
Remove the bracket. This makes everything so very much easier.
Lift the header tank clear of the battery and power steering reservoir, and tilt it towards the front of the car so that the hose underneath it is accessible AND the FL22 level is below its spigot.
Use the visegrip to undo and move the clamp, and then carefully persuade the hose to come free.
Lift the tank out taking care not to spill the FL22 out of this last open spigot.
Installation of new tank
I then placed the poly-washer spacers on the relevant studs, not necessary, but it pleases my OCD sense of rightness.
Fit the hose on the bottom spigot of the new tank, making sure it will not be stressed or twisted when the tank is back in place. I try and set the clamp into its original marks.
Fit the tank to the two studs and fit upper poly-washer and nuts loosely.
Fit bracket, and its poly washers either side of the tank flange, and both nuts,
Tighten all the nuts in turn while checking the tank is free and not stressed.
Remove the drill-plugs and fit the two hoses.
Discover the overflow spigot is pointing in the wrong direction for the bends in the original little hose, reverse the little hose end for end and it will do. Tilt it up for the moment.
Carefully decant the FL22 from the old tank into the new one. Return the overflow hose to pointing down again.
Is it just showing in the sight glass? Yes!
Run the engine until the system is up to pressure and temperature; check for leaks, a torch and dentist’s mirror is useful for the hose underneath.
Replace battery cover.
Take it for a drive around the block; is the header tank hot? Is the sight glass gently oscillating in level as the FL22 circulates? Yes! Success.
Edit. I later took it in for the 11 year annual service and asked them to change the FL22 (and brake fluid) because they were due anyway so I didn’t need to mess about with flushing or burping it etc