4.6 head woes

mornin all, another rangey with a head problem! ive got a 1998 4.6 auto with previous head issues which i had sorted, car was runnin fine did feel like it was missing slightly. took the car for an mot and mot guy thrashed the livin **** out the car to help "clear the emission" then left it running for 40mins. anyway car passed mot, i went to start the car and it turned over but wouldn't fire up i looked at the dials the red light was on and temp needle was off the scale. i popped bonnet felt top hose was solid so thought let a bit of pressure out the tank one little turn of the cap, scalded arm and a hell of a lot of water later! i waited 30 mins topped her up with hot water and she started up managed to run 1 mile then same thing happened again pulled over went for a walk returned an hour later topped up with hot water then ran 1/2mile same thing happened but made it home! checked car over thought it was a dodgey fan or thermostat or blocked rad, but they all seemed to be workin. now when the car runs for 5mins it boils up the water pump is workin so ive now taken to replacing head gasket on stripping it down there are no real signs of the gasket failling how ever one of the pistons seemed oily/wet but gasket seemed fine where as the others looked burnt n dry, the only other thing was four of the head bolts werent a tight as the others?? could it now have a warped head? or am i looking at a slipped liner im reluctent to start that job if i can help it for obvious reasons! any help would be much appriciated cheers guys! im wishing i spent the money getting my defender back on the road...

sorry to say it but think you know what is going to be said, sounds like block has let go on you.

^^^^^^^^ i agree with the above..

depends cracked blocks dont show evidence as it happens behind liner unless catastrophic what you have could be caused by block or head gasket failure ,its old enough for gasket to go ,you can test blocks but it isnt a 5min job

cheers guys bin doin sum reading going totry blowing out all water pipes n rad slap a gasket on n pray then if it fails again ill whip the engine out!

Change the state coman for sticking also have the heads pressure tested and skimmed to ensure they are ok