No joy getting those o-rings at Repco, so just cleaned-up to old ones and used Permatex blue per Deano's suggestion. Am pretty sure they are just
normal rubber, feel similar to the NBR o-rings I use in the air suspension on my Rangies. Also changed the radiator hose clamp to a worm type clamp.
The old plenum gasket was a bugger to remove and clean-off the crap left behind, but got there eventually and put it all back together. Topped up the coolant and ran the engine for a couple of minutes to see if I had missed anything. No visible leaks so far, will let it sit overnight to allow the Permatex to cure properly.
Am still shaking my head in disbelief at the location of the thermostat... the designers must be sadists to put it in such an awkward spot at the rear of the engine. Am truly hoping that does not go next.
I dunno if other VZ Commodores and Crewmans are like this, but the Cross 6 has a plastic stone guard underneath that must be removed to access the tap on the bottom of the radiator. Wondering if anyone has devised a hose extension with another tap to avoid the need to remove the stone guard when draining the radiator?
One last question please blokes (and bloke-ettes) - when I had the plenum removed, I could see a pool of coolant on what I assume is a valley gasket beneath the inlet manifold. I had no need to remove the inlet manifold as it would mean another set of gaskets to replace and stuffing around with the fuel rail. Is it safe to blow compressed air or water spray down the valley to wash out the coolant pool?
Cheers, Paul.