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Ok so my sister's car (93 MX-6 V6) started making a nasty rapping noise last week. It's been sitting waiting for me to fix it for about a week and a half. So I start it up and listen, rapping, but it doesn't get louder when I rev it, it seems to get faster but drowned out by the motor noise, which isn't much. I always thought rod knock would get louder with the motor revving. It happened while she was driving home from NY, she said it felt like she lost power and it started making noise. She pulled over and waited for my dad, who then followed her home another 10 or 15 miles, and she said it didn't always rap, but always felt wrong. I was thinking it could be the hydraulic lifters, they may have air in them, allowing then to compress and not open valves correctly, but I don't know if it would be this loud. I'd like to get a second opinion before I pull one of the valve covers, since it's a royal pain in the ass on this FWD V6, I have to pull out the huge manifold first.
The engine was rebuilt a few thousand miles ago, during the winter, by me and a friend, so the bearings should be new, but I didn't do anything with the tappets since I didn't really know anything about them. It's been running fine since then.
The engine was rebuilt a few thousand miles ago, during the winter, by me and a friend, so the bearings should be new, but I didn't do anything with the tappets since I didn't really know anything about them. It's been running fine since then.