My 3.0 (V plate) 2000 Omega V6. This car has lost coolant from day one (I've probably only done 500/800 miles in it in my ownership) and is getting increasingly worse.
It's now at the point it is emptying the header tank within 150 miles.
The compression on all of the cylinders is fine and car pulls like a train, there is no misfires. It's probably one of the best pulling V6's I've owned or driven.
The engine appears in good order and unmolested, EG plenum caps intact, everything correctly routed.
It only has a total of 98k miles. The coolant (albeit blue antifreeze) appears to have been well maintained.
All of the pipes around the back of the engine appear dry as a bone, as does the "v".
When running, I can see a very small, intermittent stream of coolant running down the block, as you look down from the top into the crank sensor, oil filter housing area, and back a git where the gearbox bellhousing bolt goes through the block and into the gearbox on this side.
I know it's not a '98 model, but it is a 3.0. I reckon the head gasket has slightly let go in the rear corner on the passenger side, as a few other members (myself included) have seen and experienced.
My understanding is that the firing rings around the pistons on the head gasket remain intact, (hence no misfires or over pressuring) but that the composite material on the gasket between the water jacket and the outside world deteriorates, hence the coolant making a bid for freedom
Any thoughts?