I own a 1999 Volvo S70 with 97,000 miles on it.
Very recently my engine has began to make a very alarming, very loud metallic grinding/rattling noise. I know it is difficult to give advice based off such a common noise, so I'll do my best to describe how it happens.
It only happens when my engine is hot. I will drive it for 10-15 minutes with nothing, park, drive it again within the next 10 minutes and experience the noise. It happens most commonly when I am accelerating lightly. If I push it up to about 2,000 rpms when I begin to hear the sound, it will usually quite or subside, only to return when I maintain the speed. I also hear this noise when I brake hard. If I hear it with a hard brake, and I let up a bit to come to a slow stop, it usually subsides.
Now for the warning lights. My check engine light is constantly on due to a malfunctioning wheel sensor, so who knows if that is also related. My Brake and ABS light come on occasionally, assuming due to the same issue. Since this issue has surfaced, I have noticed my SRS light is constantly on. Seems unrelated though. The important one: My oil pressure light blinks on whenever I am at a stop, or coasting. I immediately checked my oil and it was alarmingly low. I had it replaced the next day. I had only driven maybe 15 miles with this noise before the oil change. Now that it is full I am still experiencing both the oil pressure sensor and noise. Have driven an additional 15 miles since.
Afterward I read a bit on what happens if you run your car on too little oil. Someone recommended to let my car run a bit, then rub a bit of the oil between my fingers to feel for tiny metal shavings. This was supposed to indicate permanent engine damage. Thankfully there were none.
The first day I heard the noise, I continued to drive despite it because I was working (delivery driver). My manager told me to take it easy on my car until she could find me a replacement. The next delivery I took, smoke/vapor started to pour out of my vents. The best I can describe its smell: stuffy mildewed room filled with old corn. After sniffing at it a lot, trying to place the smell, I got an intense headache around the back lower end of my head and neck. I doubt it is related to the engine issue though, cause I immediately popped the hood and no smoke.
After I had the oil change, I drove it for the second time (besides to get the oil and filter) 3 days later. I had to work and I assumed it was the sound came from the oil issue. The first delivery went fine, then my engine heated up and the sound persisted again. This time I noticed a burning rubber smell (a bit putrid too) in and outside of my car. No vapor from the vents though. I noticed a light smoke around the front end of the car. Hard to tell where it came from. It was a night shift and I only saw the smoke in front of my headlights. I figured out where it was coming from in my car. A small circular hole/vent on the left end of my dash which is blocked when the door is closed.
Again I told my manager I had to stop, she sent me on one more delivery while she called in a replacement. This time my car was making the noise louder than usual at very slow speeds and I noticed my battery light (along with the usual oil pressure light) on right before the engine lets out one last grinding noise before dieing. This happened as I was coasting into a parking spot. At least it had good timing...
After making the delivery I was able to start the car after turning a few times, fainter than usual. I drove home right after and walked to work to clock out.
Also worthy of note: Once while starting my car after a delivery, on the first day, the grinding noise was accompanied with the start-up. That was my last deliver, so I did not start up the car again while hot until after the oil change.
Some engine service in the past year: Upper engine mount replaced. All five spark plug wires replaced and spark plugs wiped clean. Oil got in the terminals and not all 5 cylinders were firing.
If desired, I can attempt to record the noise and post it on youtube, though I believe links are disabled in this forum. I'll find a way if someone is willing to help!
