Strange grinding/scraping/rattle after overheat.

[olly]

Hey, I just finished the install of a new/used longblock into my car and was out doing a bit of driving, nothing rough. While sitting a stop sign the stock temp gauge quickly jumped into the red. I turned the AC on so I knew I would have at least one fan on. There is no AC compressor in the car. The temp gauge jumped back to normal (pretty much in the center). After that I shut the car off and pushed it across the street into a parking spot and let it sit for about 5 hours. I started it back up and its making a strange rattle. drove the 300ft to my house from where it was parked and the rattle persisted. I got home and began to check some stuff out and found that my harmonic balancer bolts had stretched and began to back out. I replaced them and used some loctite this time but the grinding/scrape/rattle is still there but significantly less. It seems to be coming from the back of the engine. It doesn't really sound like rod knock to me. The car still has oil pressure. I am at a loss to what it could be since it wasn't all the harmonic balancers fault. I'm not spinning the front balance shaft either. Other than that the car is mostly stock except for the free mods. Any insights would be great. Thanks.

 

[luv2rallye]

Water pump bearing? Harmonic balancer seperation?

 

[olly]

Would harmonic balancer seperation be obvious or would I have to take it off the car to find out? I don't think its the water pump because the pump is relativly new and like I said the noise is coming from the back of the engine it seems, could it be a balance shaft bearing?

After starting the engine again, it's a definate grind or scrape rather than a rattle. Tightening down the harmonic balancer got rid of the rattle.

 

[mmkd]

Any followup to what the problem was? as I'm having the exact same problem....

 

[olly]

I've been rather busy as of late. But I did get out yesterday and pull the harmonic balancer off and turn the engine over by hand. Nothings binding up or grinding. Water Pump spins free. Nothing in the oil, the oil pressure is fine. I cant find another reason why the harmonic balancer would have backed off if it wasn't starting to go south. It's getting replaced as soon as I get my bills paid.

 

[olly]

Well I got the new harmonic balancer and installed it and got the car fired up today. No issues with rattle or scraping, but It sounds like the balance shaft closest to the firewall of the car is bouncing around or wobbling inside the engine. I also changed the oil after I installed the new harmonic balancer and ran a magnet through it and didn't have any metal bits come out with the magnet. I suppose I will try removing the balance shafts.