Segfault

My 2.2 L '03 suddenly developed a knock under camshaft cover, I can hear it inside. Frequency seems to be 1/2 of engine RPM. Otherwise the engine runs fine, steady idle and cruising.
Before I take it apart, what could it be. Is it some typical Cavalier issue or I have to dig deep? May it be one of lash adjusters has gone bad?

EinST

2.2L Ecotec? Before you tear into it, check the oil filter. I've seen some aftermarket filters with a tinny O-ring around the oil filter nipple. If that O-ring fails somehow, you can have inadequate oil pressure despite a full oil level on the dipstick.

Segfault

Yep, Ecotec. I inspected the oil filter and didn't see anything wrong. However, I replaced it and now I cannot hear this knock inside but it is still there when listening under hood.
How should I go about measuring the oil pressure on this engine? How much it should read?

EinST

The oil pressure specification is 50-80 psi @ 1000 RPM. I'm not sure if there's enough clearance to hook up a pressure gauge in place of the oil pressure switch with the starter in the way, though. Are you sure you aren't sensitized to the noise? That engine normally makes all kinds of ticks and clacks. Try changing the oil but send a sample of what came out for analysis to Blackstone Labs or something.

Segfault

First, thanks for helping me with this issue.

I just changed the oil and the filter (aftermarket), the trouble started a few hundred miles after. That's why what you said made perfect sense.
I have two Cavaliers, I started them both with open hoods and the other one is much quieter ... but it also has less miles on it ...
I use Amsoil 10W30 in both.
It may be I'm too sensitive, I do not remember hearing that before oil change ... maybe I just wasn't listening.
I'll drive it for a while and see if it gets worse.

EinST

You're quite welcome, though you've been a steady contributor yourself. I hope nothing worse comes of it with that noise.

Call me an oil filter snob but I make a point of using only ACDelco PF457G filters (made in USA) from RockAuto on the Ecotec. I came across the same filter P/N in Walmart a couple of years back but it was visibly different, including the tinny O-ring around the nipple. That O-ring is the only thing that keeps the pressurized oil from leaking back down to the sump and thus I wasn't impressed. Also, the oil filter cap on the Ecotec went through a couple of revisions (for increased bypass valve relief pressure). The current P/N is ACDelco PF458G which comes with the filter.

Segfault

I purchased a box of WIX filters from RockAuto long time ago. This is the first time one of them failed. But it definitely did. Today I used this Cavalier to commute and it is back to normal. With ambient 85 F, after 35 miles it sounded as before when I parked it at work. (When I took it for a test ride I wasn't sure the oil was warmed up.) Meaning I had to turn off the radio to hear the engine.
I'm kicking myself for not thinking of oil pressure first.
Thousand thanks, EinST, without you I'd be pulling my hair and doing lots of unnecessary work.
If you ever happen to be hereabout please consider you have a friend here.

EinST

You're quite welcome. I can't really take the credit since it was just the first thing that came to mind.