Ticking from engine bay

MRFALKY

MEMBER
2007 CHEVROLET LUMINA
3.6L
V6
2WD
AUTOMATIC
173,983 MILES

Hello ladies and gentlemen,
I bought a second-hand car about two months ago which started developing a ticking sound from the engine bay. 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. I have even tested it in a tunnel to make sure it disappears. This only happens when the car is warm as well. When I start the car in the morning the sound is not there and does not come until the car has been driven/warmed for a bit. The previous owner was a very old man in his late seventies and he had no crash/maintenance logs. He never drove the car above 90 KM/h when he had it in his possession. When we first bought the car it was near perfect until I pushed it to around 120 KM/h a week after we bought it. It started making the sound from that day. We thought maybe the oil is bad so we went and did an oil/oil filter change. The sound went away for around a couple days then came back so we took it to a mechanic. He disassembled the engine and told us what the problem was but I am not a car-savvy person and do not remember what he told us. I only remember him saying that the "crankshaft" needed changing. Once he gave us the car back the sound had completely disappeared. It stayed like this for around a month until the sound came back around two weeks ago. From then we have changed the oil/oil filter twice. Each time the sound disappeared for a couple of days and then came back. I wanted your honest opinion before we have to take it back to another mechanic and get ripped off again.
This car listed above has a four speed transmission with 280,000 KM mileage.
Check engine light on.
Oil being used: Mobil Super 1000; 20W-50 XHP.
Link to video of my car:- https://www.youtube.com/watch?v=zMfMyhurojE&t=1s
Recent maintenance - Transmission oil change only because of leakage (not filter).
A/C compressor electricity wire was loose.

P.S.: I live in the middle east where the temperatures can hit 40C mid-day.

1 Reply

JACOBANDNICKOLAS

MECHANIC
108,295 POSTS

First, the manufacturer does not recommend that heavy of an oil. Check the oil cap. It most likely recommends 5w30. Since the temperatures are that high, I would strongly recommend checking the owner's manual to determine what the manufacturer does recommend under those conditions.

Next, the crankshaft is at the bottom of the engine. Thus, a ticking at the top has nothing to do with the crankshaft. If there is a bearing issue with the crankshaft, you will experience more of a knocking sound rather than a tick. Which leads me to my next suggestion.

Since the sound is at the top and specific to one side, it sounds like a lifter issue, which has nothing to do with the crankshaft. Also, a slight exhaust leak from one of the exhaust manifolds can make a ticking sound. If you are confident it is not an exhaust leak, I recommend checking the oil pressure when the engine is warm. When the engine is cold, the oil will be its heaviest. Hence the lack of ticking. When it warms up, it will think due to the heat. If the pump is going bad, it will most likely begin to lose pressure then.

That is where I would start. Keep in mind, the present oil pressure sensor is electric. I recommend using a mechanical gauge for the most accurate reading. Additionally, I strongly recommend having the computer scanned to determine why the check engine light is on. It may be a misfire resulting from a head gasket. If the gasket leaks, it could allow coolant to mix with the engine oil. That may be why after the oil is changed, there is no noise for a period of time.

I hope this helps.