TRAVELINGWITHTOOLS

I worked on this Lamborghini 400GT project back in Colorado several years ago. The car had been stored without the correct mix in the cooling system and the crankcase was broken by the expanding ice. A new old stock crankcase was somehow tracked down, and I was charged with transferring all of the components into the new block. So it was a complete engine build using most of the good parts from the original engine.

As I was close to final assembly, which usually starts with placing the crankshaft into its bearings, I had one last close look at the thoroughly cleaned crank. All of the plugs had been removed from the oil drillings and brushes run through with solvent to dissolve any gummy oil residue, before a final bath with hot soapy water, blown out with compressed air. The drillings were absolutely spotless. But to be certain, each hole got inspected by shining a light into it and having a very close look.

That was when I discovered debris inside the crank that had lived there since the last time it was assembled and somehow did not get washed out. It was a loose piece of an old brass drilling plug that somehow could move around in the hole, but it was trapped and couldn’t get out. I had to break it into tiny pieces to remove it.

It was very strange, because you’d think if it could move inside a drilling that it would simply fall out. Looking back at the photos, I think the hole in the main journal that held the debris was not a through-hole, but blind, so the cleaning brush was ramming the debris to the bottom of the hole. The drilling carrying oil from the main journal to the rod bearings ran diagonally through the neighboring rod journal and there was a pocket where the two drillings intersected.

In any event, the engine lived its previous life with this loose chunk of brass inside the crank, and it neither plugged up the oil flow nor escaped to damage the main bearing. Pretty amazing!

I’m glad to have found it though, because it could have been a show stopper if it got free. Double check that part! And I suppose you could check the anti-freeze before it gets cold…