previous UOA, and exposition to problem.
i knew it would be a short run, so i emptied the odd oils left on my shelves. this was 4qts Exxon SuperFlo 5W20, and 3.5qts Chevron Delo 15W40. used 400 miles, with a purolator PF1218-equivalent oil filter. i'd gone through the top end a few times trying to track down a noise. during this fill, on the dyno, the noise became much worse. it sounded like it could possibly be a spun rod bearing. i limped the car home and drained.
i started tearing the engine down and found the problem before i got the UOA results back. turns out the gear teeth on the cam sprocket that drive the water pump gear/shaft have been worn off. after much careful measurement, i can't find a cause. it might be that the gear wasn't hardened properly. a search on some f-body and vette forums shows this is something others have experienced, no one seems to know the real cause.
what shocks me is that the UOA looks perfect, yet there were steel shavings all over the inside of the engine (but not in any of the oil galleys). the bearings look great. i don't think i hurt the engine. i'm not sure if good filtration saved it, or if the metal just never made into the oil pickup tube to begin with.
from blackstone:
enjoy!
-michael
i knew it would be a short run, so i emptied the odd oils left on my shelves. this was 4qts Exxon SuperFlo 5W20, and 3.5qts Chevron Delo 15W40. used 400 miles, with a purolator PF1218-equivalent oil filter. i'd gone through the top end a few times trying to track down a noise. during this fill, on the dyno, the noise became much worse. it sounded like it could possibly be a spun rod bearing. i limped the car home and drained.
i started tearing the engine down and found the problem before i got the UOA results back. turns out the gear teeth on the cam sprocket that drive the water pump gear/shaft have been worn off. after much careful measurement, i can't find a cause. it might be that the gear wasn't hardened properly. a search on some f-body and vette forums shows this is something others have experienced, no one seems to know the real cause.
what shocks me is that the UOA looks perfect, yet there were steel shavings all over the inside of the engine (but not in any of the oil galleys). the bearings look great. i don't think i hurt the engine. i'm not sure if good filtration saved it, or if the metal just never made into the oil pickup tube to begin with.
from blackstone:
all else 0. (yes, really, anything not listed above was 0, including Fe!)
enjoy!
-michael
