I'm not entirely sure what the bug is here, but the rolling machine operates extremely slowly, and the stirling engine eventually builds up enough backed up energy to explode.

So...what changed your mind to go the RF route? Before I left, about 4 months ago, BC devs were stark against RF and held onto their MJ power system.

I wasn't a BC developer back then. laughs

The main problems were these:
a) Mods were stopping to support BuildCraft. I think the lastthree mods which commited to supporting Minecraft Joules in early September were RailCraft, OpenComputers and Applied Energistics 2. For a mod which is supposed to form the core of a pack, that's fairly little.
b) The BuildCraft 6.0+ MJ API was actually very similar to Redstone Flux in behaviour, just with a lot more abstractions thrown in. But few people know about this.
c) The RF API is a lot cleaner than either the "BC 5" or "BC 6" MJ API.

Low priority, as RailCraft is the only mod left to depend on BC 5 MJ (and it has an RF beta version for private testing!). I plan to kill off the BC 5 MJ API as soon as that happens.

Indeed, and hurray for that! Just thought I'd let you know.

Closed because I do not think I can do anything big about it. Try powering the Rolling Machine with more engines or stronger engines to nullify the effects of energy loss.