4.6 strange overheating problems

[russ1]

Morning,

Bit of a strange one for you lot,

Me dad bought a 2001 4.6 vogue a few years back ( even after me telling him not to touch a 4.6 )

He got it back and it had a tapping on the engine, so after the told you that you would have problems banter he just ran the car,

He must have done in excess 20,000 miles with no problems, yes it was losing water but just about the same as my disco 2 v8 ( topping up the tank every month or so )

About 3 month ago I got a phone call saying the temp had started to go up and he had pulled over, told him to let it cool and check the water and top it up bleed it etc.

After this it was fine and he has done another 5000 or so miles

Now he's gave me the rr, and on heading to silerstone last weekend I had done around 200 miles of speeds around 80 I stopped to fill up with gas set off again with in 5 miles temp shot up pulled over rad top hose was solid, let it cool and had to put upwards of 6L of water in, started it up temp was fine so headed on to sliverstone at a slower speed with heaters on max etc. Not a problem getting there,

Next day when it was 100% cold I bleed the system but if I start the car with the header tank cap off after a few seconds it bubbles over, had a quick smell and can't smell any exhaust gas etc,

Set off home on sunday never dropped below 80 and a few bits i was in 3 figure speeds and the gauge never moved!

On talking to me dad he had the same problem leaving the cap off when it overheated with him.

Going to do a comp test sometime this week, there's no water in oil etc,

Rovacom shows no faults

Any ideas?

I have a 4.0 rpi v8 in the garage but it's on gems, are the blocks heads etc the same? Trying to come up with ideas, could I use the 4.0 block and heads and change the crack rods, pistons intake sensors etc? Is it a different cam?

Any ideas would be great!

Thanks

Russ