COLD START GRINDING SOUND (REVISED)
[Please read entire post before answering]
When starting my car, there's a horrendous grinding/metallic/vibration noise coming from the passenger-side of the engine block. It is fully apparent when the car is COLD. Goes away after about 5-10 minutes drive time, and is much worse in the morning when it's cold outside. The "grinding" comes and goes in those first few minutes. The grinding almost sounds like "slipping".
- When driving down the street (cold) with the sound, I put the car in Neutral while still moving (approx 20MPH) and the sound was still there.
- After a few minutes, the sound becomes more intermittent. I noticed that it appears at the top of the RPM's as it's changing gears (around 2,500). I also tried this is in manual Geartronic mode and noticed it happened again around 2,500 RPM's and continued as the RPMs fell, then stopped as they were increasing, then reappeared again 2,500-3000.
- After about five minutes, the sound will stop, but will kick in for a split second, as if something is "slipping"
- As the noise dies down a bit, it comes back for a split second when I go over the speed bumps on our street -- and always on the down side of the bump.
- As the noise dies down a bit, I may still hear it when making a hard turn.
- After the car is warm, I feel like it's still there (though much, much quieter) in Park and Reverse (at a standstill with the brake on), but goes silent in Neutral and Drive (again, with brake).\
- After about 15 minutes of drive time, the sound is gone.
MOUNTS: I did notice that the rubber part of the torque rod was cracked and had it replaced. My mechanic suspected that was the problem, replaced it and told me it was fixed, but when I picked it up hours later and started it cold, the noise was still there. (Note: He also did a 52,500 service on the car which included an oil change.)
Unfortunately, by the time the shop can get the car up on the rack, the sound is gone.
So my question is: What can be causing this issue? I guess it makes sense that it could be some kind of mount issue, but why would the sound go away so quickly? Remember, it's completely gone after the car warms up.
Searching the web, I found this video of a Volvo 850 that appears to have a similar sound -- though I will note it is very hard to compare sounds from a YouTube video!
On it, he claims the issue was a faulty bearing in the water pump.
So far (on 2carpros), suggestions have included (1) the power steering pump, (2) loose torque converter bolts/nuts, and (3) belt/tensioner.
Any thoughts most appreciated! Thanks.
Monday, January 28th, 2013 AT 5:42 PM