First off, let's get the modpack details out of the way :
FTB Loader-installed Mindcrack 8.2.0 for Minecraft 1.4.7
Optifine HD U D3 1.4.7
MinecraftForge Universal 1.4.7 126.96.36.1994 (was needed to get optifine to work)
Soartex Fanver texture pack
OMG WTF it blew up again ?!?!?!?!?
The basic setup was....
Biofuel tank in the back feeds four combustion engines sitting around (back / left / right / under) a magma crucible.
Each combustion engine has it's own Aqueous Accumulator sitting in a X-A-X arrangement (X being water source blocks, A being the accumulator) with unobstructed / non-shared pipework feeding it water for cooling.
I have a Chunk Loader sitting about 6 chunks away, set to keep a 10-chunk radius square loaded - this has been visually verified with turning the lasers on.
During the startup of this setup, I sat and watched all of the input pipes feed the engines fuel and water with no hassles whatsoever.... the engines built up to the 4900.5 temperature mark and were 'yellow'.... but they were stable for the 20 minutes I sit and watch it, and for the 30-40 minutes afterwards where I wander off outside of the chunkloader area to gather more materials.
I get back from foraging, lava is being output just fine, the MFE is filling up nicely from the thermal generator I have on the end of the lava pipe... so I turn my back for 10 minutes, and *BEWM* the engines/crucible arrangement detonates for no apparent reason. When the smoke clears, one of the combustion engines (the only one left standing) is glowing red.
I'm at a loss - I've checked that the chunks are being loaded, I've checked that the water sources / combustion engines are in the same chunk, there were no mobs anywhere near the reactor at the time, it wasn't a creeper, I've checked the wiki entry....
To use a combustion engine you must first fuel it with Lava, Biofuel, Oil, orFuel and also keep its cooling tanks full of water. Without water the engine will quickly overheat, so it's advised to have an infinite water supply for the combustion engine to prevent explosions. It provides a clear warning when it is overheating: The combustion engine will ONLY become orange or red when there is no water left. While water is present the engine will heat up to 4900.3 degrees Celsius on oil, 4500.5 degrees Celcius on biofuel and 4900.6 degrees Celsius on fuel. The explosion of a combustion engine occurs when its temperature reaches 10,000ºC and is large enough to break 2 layers of stone.
I've made sure that there's sufficient fuel and water being fed into the combustion engines.... and I have two other combustion engines literally 10-20 blocks away from the explosion site - being fed from the same biofuel source, each with their own Aqueous Accumulator feeding them water, and they have been running constantly for the last 12 hours... not the 'less than two' hours that it took for my lava production line to explode.
Can anyone think of why this may have happened ? Quite honestly, I'm at a loss, so I throw myself on the floor of the court (so to speak)..... Hopefully someone has an idea as to why this has now happened twice.