2005 5.3 Vortec Sounds Like A Harley
My 2005 5.3L sounds like a Harley! Over the past
few weeks it's developed a low throaty roar in the
bottom of the motor. Originally I had a pretty bad
tapping lifter so I put some Seafoam in the oil and
ran it for a few weeks. Just before that I also
noticed this new noise from the lower engine area.
It's gotten much worse. It gets louder/faster as the
engine revs but then subsides at highway speeds
and also when not under load, like when coasting.
Engine feels rougher now and corresponds to the
noise. The noise goes down in park, but not
completely. It also makes the noise in reverse. It's
almost like a rattle but lower. I don't think it's piston
slap because it doesn't go away and it's getting
worse.
Today I drained the oil and pulled the oil pan off
hoping to at least see something that could be the
problem. Cylinders don't look worn or gouged,
piston rods look fine, no metal bits in the oil or the
pan.
Once I got it back together, the low oil pressure
warning came on and stayed on, and the gauge
needle barely moved until I got driving. Under
constant load at 45mph or so the gauge read just
under 40, then it dives again almost to zero when
the car is stopped. I kind of wonder if this is just
the sensor being screwed up after I cleaned the
pan.
Could it be the oil pump has failed? Or, could the
knocking noise be something else like an exhaust
leak? Any advice on diagnosing from here? I really
can't even afford to have a shop look at it, but I'm
pretty confident I can do whatever I need to on my
own, I just need to know where to look.
I appreciate the guidance!