My 1hz # 1,2 and 3 big end bearings cooked and ended up like alfoil. There is no damage to the bores or pistons and the cam is fine. The journals on the crank are badly scored and some of the main bearing caps have miner scoring. It got hot going up hill and am left wondering what happened? The oil level was fine, with a full radiator. The odometer says 380,000 klm. The # 1 BE journal is badly damaged. I've got my hands on another 1HZ with 330,000 on it which is running fine. I was thinking of taking the sump off and changing the BEBs ? Is this necessary?