Hello all,
I have a 1996 Chevy Z28, LT-1 5.7L V8 engine, six speed manual transmission. The vehicle has 147k miles.
Ever since I've owned this car (since about 68k miles, in 2000), it has had a low-RPM "growl" coming from the engine/tranny. This generally occurs between
700-1000 RPM, and starts off low, with a crescendo to peak volume around 1000RPM, then tapers off as the engine revs up. It is a steady growl (no chittering, except when very, very low RPMs cause bogging down) that varies with engine RPM. It does NOT occur when the vehicle is out of gear.Any thoughts on what this could be?
I've had the clutch replaced, along with throwout bearings, etc, and thus this is likely not the culprit. I have also had the differential replaced with a Jasper reman, as the original was noisy and had scored bearings/noisy gears. So I'm pretty sure these aren't the problem.
That leaves me with engine (worn rear main bearings?) or tranny (worn input shaft bearings or similar?). The car runs perfectly, does not burn oil, does not have low oil pressure (generally 50psi or so cold, 25-30psi hot, idling, according to the OEM dash gauge), does not shify roughly; but I have had to replace the rear main seal a couple of times (maybe 3) since I've owned it. Although I've been told this is a common need on the LT-1.
Any thoughts on this low-RPM growl? My spidey senses are saying "input shaft bearings to tranny," but I'd like to get some feedback. Lastly, any thoughts on repair for this item?
Thanks in advance, Josh