I am looking for an experienced eye here. I am new to the Audi world and this forum so work with me.. Just bought a 2000A4 Quattro with a blown engine. Took it apart enough to see a bearing in the oil pan. I bought a junkyard engine with 58,000 miles. It had been sitting for almost 2 years but it looks to be true in miles and good condition. I had to swap out oil pans and I inspected the crankshaft while it was open. I noticed some blueing coming from the connecting rod journals. The engine that was in the car (and blown) also had blueing but much more. I since have inspected the rest of the connecting rod journals on the blown engine to get a better gauge of what is damage and what is not. (I don't want to tear into the junkyard engine too far if I am going to return it). Although there are a fair amount of areas with blueing around the rod journals the overall damage in minimal. #4 bearing was gone and in the pan. 1 bearing had some scalloping or galling on it. The rest of them looked pretty good considering this engine had 108,000 miles on it. Even the damage from the rod journal with no bearing to the the crank is minimal. So, my question is... Is it normal or acceptable to see any blueing on the crankshaft? Are these motors that bulletproof or are the a weaker Audi design?

 

I have looked at the same thing on my 2.8L, I am fairly sure that the bluing on the crank is from the heat treatment process used on the production of the crankshaft. It takes approx 500 deg F to cause this. As the bearing on my engine are in fairly good shape with 160k on it I am fairly confident that the bluing is cause by the heat treatment of the crank in the manufacturing process. Pop the cap and check to make sure the bearing are ok and you should be fine.