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Chevrolet ticking under 1000 RPM

Hello fellow car enthusiasts,
I bought a second-hand car about 2 months ago which started developing a ticking sound from the engine bay. The sound started 2 weeks after putting the wrong weight oil. I put 20w-50 in the car when 10w-30 is recommended. A week or two after the sound started I changed the oil back to 10w-30. The sound went away for a couple of days but returned. Leading me to do another oil change yesterday, the sound went away as soon as the new oil was in but started making noise again today. The sound is coming from the top/passenger side of the engine. This ticking sound is only there when the car is idle. It completely disappears when I go past 1000 RPM. The “Check Oil” light also comes on at random and stays on for 5 seconds at most then goes away. There is also a Check Engine light with trouble codes for the O2 Sensor in Bank 2. Could it be oil sludge preventing proper oil pressure or a dying Oil Pump? Can anyone suggest solutions or causes? I would greatly appreciate your advice!

The car is a 2007 V6 Chevrolet Lumina with 280k kilometres on it. The previous owner did an engine workup (Timing belt, Crankshaft, some bearings, etc.) at around 250k km.

Sounds like lifter noise if it only does it at idle. Are you sure the car doesn’t take 5w30 (not that it’ll probably make much difference vs 10w30)?

I had a 94 Chevy truck that developed lifter noise, very similar to what you describe, and my Buick v6 has a little lifter noise also, usually only notice it at or near idle and when the engine is cold. I’m ignoring it on the Buick, as it isn’t severe and not much can be done as far as I’m aware.

My first thought was lifters, and they may ultimately be ticking, but they won’t trip a fault code.
First get the codes read (the O2 code may prompt you to check or replace that sensor). Then, if it’s still ticking, address the ticking. Injectors can tick, and it is possible (albeit perhaps not probable) that a failing injector is causing both the sound and that unknown fault code.

NOTE: if that oil pressure light is coming on when the engine is idling and/or hot, suspect worn crank and/or rod bearings. This will cause the oil pressure to drop off under the described conditions. Diagnosing this means checking it with a pressure gage.

Oil pumps are relatively imprecise parts that spend their lives awash in fresh oil. I’ve never seen one be the cause of failing oil pressure. In the overwhelming majority of cases in old engines the loss of oil pressure under the conditions described above is due to engine wear.

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That engine has a timing chain, not a timing belt.
He replaced some of the bearings, but not all of them?
:thinking:
I suspect that this engine is simply tired, and badly worn.

I was in line at kfc, and heard a slight ticking at idle, I have an oil life monitor that has never gone off, but usually change my oil regular old dino about 5k or so, I hear nothing if I am not in a drive up lane, so my thought go for an early, 3k mile oil change, maybe upgrade to castrol, I do not want to do a full boat synthetic at this point, but imhop it is not at the disaster waiting to happen at this point. hmm, should go check the oil for color and level.

Looking a little dirty, and getting close to a quart low at 3k miles, go for 3k oil change I guess, anything else I should check? The drops on the white letters look fairly clean.Time for a shot of marvel mystery oil?

Personally, I’d top it off and change at your usual 5k mile interval, but that’s just me.

Probably just normal engine wear, expected at 280K, esp if the routine maintenance & service wasn’t always kept up to date over the past 10 years by the prior owners. You’ll probably going to have to just live with it, keep on driving but drive conservatively, avoid rapid accelerations, going up really steep hills, heavy loads, anything that critically loads the engine. Suggest to replace the oil and engine filter every 3,000 miles going forward, and keep it topped off in between if it ever gets more than 1/2 quart low on the dipstick. Use the exact oil specifications per the owner’s manual. Your lumina probably has variable valve timing, and that technology is very sensitive to the oil specs. Prior to VVT some variation in oil specs could be tolerated, but not anymore. Check the maintenance schedule for your car, if it specifies it needs occasional valve clearance measurement/adjustment, time to do that job.