Engine Rattle

[TryMeGT]

I will try to keep this short in explantation. When I was racing, I made a dumba** mistake. Did my burnout in 2nd gear, when I staged, I did not shift into 3rd. During the pass, it started to cut out and break up. Saw 1.9` of KR so I got out of it. Looked down at the shifter and saw I was in 2nd. On the return I hear a rattle under the hood at about 2000rpms. Did not continue racing. My guess is that I overrevved the motor, I know I hit 84-86mph in th 1/8th, don't know RPMs. Drove the car home, the rattle is fully audible above 2000rpm, but it does not show up as knock on the SM or DS. Pulled both rocker shafts and push rods, did not see any cracks and push rods were straight(both are thicker pieces from Postons). Ran a compression test, all cylinders between 140-150psi. They also built up incrementally. I ruled out a bent valve, but is that accurate. I put a stethoscope to the vavle covers, and don't really here anything. I do hear a tick in the cam sensor and the front cover, just do not know if this is normal. Any suggestions of what to look for, check out or review. Thanks for your help,

 

[86 TR]

I did the same exact thing as you. I left the trans. in 2nd gear to do the burnout and left it when I took off down the quarter. Mine had no KR during the run but on the return road I could hear a knock, or rattle on the return road. Got the car home and I knew I hurt something it turned out to be a spun rod bearing.

I think your gonna probably have to take the engine apart and see what is making that noise. Is there any metallic look to the oil?? Im betting you either spun a rod bearing or a main bearing. I could be wrong though.

Good luck.

 

[TurboTnZ06]

Take yer belt off, pull the intercooler and remove the yellow fan. Make sure you crank bolt is torqued down. I had one come loose jsut barely and it cracked and wobbled around making a real rattling sound. I was baffled that I couldn't find it until I started tearing the motor apart and pulled on the fan and it moved in a way it shouldn't move. Just a thought and it is easy to checkk, unfortunately, if it is the problem then you need to buy a new used balancer since they crack very easy.

 

[TryMeGT]

Thanks Guys, I will drain the oil tonight and check both suggestions. The motor has only about 2000miles on it

 

[TryMeGT]

It is number 6 rod bearing. It did not spin but it is chewed up pretty bad. Need to tear her all down and clean her up. I may need a new crank as this one has a slight groove in it and I do not think it will polish out. It is already .010 - .010 and I won't go .020 Thanks for your help

 

[SouthernCal GN]

.020 is fine.

 

[cabech984]

It is number 6 rod bearing. It did not spin but it is chewed up pretty bad. Need to tear her all down and clean her up. I may need a new crank as this one has a slight groove in it and I do not think it will polish out. It is already .010 - .010 and I won't go .020 Thanks for your help

Does a rod bearing knock always stay at the RPM or is it intermittent when it knocks? Did/ Would you notice low oil pressure?