Rattling and whinning noises

[Dwilsey]

Okay so over the past week my truck began making this terrible loud whining/whirring sound and began making a rattling noise from around the oil pan area. No engine light for low oil pressure or the gauge didn’t seem to be low. I was close to home so I finished driving home due to no alerts.
So, before I proceed any further; allow me to share that over the course of the past 5 or 6 weeks I have had the knock sensors replaced followed by the rear main seal. Anyways, I get home and open the hood to find that my oil cap was never put back on by the mechanic that replaced the rear main seal. Oil was 2 quarts low. I have a video of the loud whinning/whirring noise but not the rattling. Rattling only occurs when in drive going 25 to around 45 mph. So, I am wondering if this could be the oil pump? Or, any other suggestions? My truck is a 2002 chevy avalanche Z71 4x4 with a 5.3L and about 241K miles.

 

[Raekal]

Presuming at least it hasn't been "normal" to see this level of oil consumption even when your rear main was leaking. immediately return it to the mechanic in question. They are liable for any damages caused by their negligence. Or of they are less than trustworthy, take it to a dealer to have it documented and diagnosed. The oil was either never put in there, leaked out, and/or you have the onset of serious engine wear issues. Rattling can very easily be the onset of lower end knocking (or is). I implore you in these situations not to play around with it, be diligent. Document absolutely everything.

Either way, this isn't something i'd feel comfortable telling anyone to hold off on. Once you know the extent of the repair you can decide on what to do next. if you werent going to do the work by yourself, a mechanic will just include the diagnostic fee with the repair and you wont have to guess. You dont want to start doing work on it, and then getting stuck with an engine replacement all because you've done more work to it since the last repair. It's hard to prove anything after that.

 

[Dwilsey]

Nope. It wasn’t even going lower than a half to 1 quart . My wife was getting annoyed (and me too) with the oil leaking and staining the driveway. It is idling very well and in and out of drive, reverse and everything until it heats up. That is when the intermittent rattling begins. So intermittent, I cannot get a video of that at all. Needless to say, I’m not going to have work done on it by the previous mechanic. He just wants to blame it as being an “old truck” and I should be checking the oil frequently. Not sure what that has to do with him not putting my oil cap back on?? However, when I informed him and he informed me he couldn’t check it out for at least a week; I notified him I was having it towed somewhere else and to put the key inside the truck. Interesting enough, I have him on camera putting on a new oil cap.

 

[Raekal]

Nope. It wasn’t even going lower than a half to 1 quart . My wife was getting annoyed (and me too) with the oil leaking and staining the driveway. It is idling very well and in and out of drive, reverse and everything until it heats up. That is when the intermittent rattling begins. So intermittent, I cannot get a video of that at all. Needless to say, I’m not going to have work done on it by the previous mechanic. He just wants to blame it as being an “old truck” and I should be checking the oil frequently. Not sure what that has to do with him not putting my oil cap back on?? However, when I informed him and he informed me he couldn’t check it out for at least a week; I notified him I was having it towed somewhere else and to put the key inside the truck. Interesting enough, I have him on camera putting on a new oil cap.

Yep, take it to a dealer. Save that footage. let them have an engine tech take a look at it. The 5.3l is a gm staple and they know what is/ isnt normal for it's age. I'd check your oil again to make sure the guy didn't sneak any in. When you take the dipstick out, take a flashlight to the oil and inspect for sparkly bits. (might be pretty dark if it's that low). If you have an oil change done, keep the old filter just in case.

The weird thing for me is that realistically, the oil cap really doesnt do anything aside from keeping various vapors inside the engine. The oil level is well below it's opening and if it was getting out though there, you would know. The oil would be covering the engine, engine cover, and on the hood of the truck.