DAYWALKER Posted December 21, 2012 Report Share Posted December 21, 2012 hello. do anybody know if detonation can cause spun bearing. after boosting and have a couple misfire and then a loud knock. after i heard the knock i let off right away but after i slow down i heard knocking noise. car still boosted fine and hold strong at 17psi. the first thing i thought was sh%t i just bent a rod. went home and check the compression. to my surprise all cylinders was at about 175psi and 180psi. so i'm thinking that i must have spun a bearing since the car have good compression and still running smooth and strong. but is that possible to have a spun bearing from a detonation? Link to comment Share on other sites More sharing options...
Tightmopedman9 Posted December 21, 2012 Report Share Posted December 21, 2012 A bent rod will not cause a loss in compression unless it was so severly bent that the skirt was broken causing the piston rings to leak. Link to comment Share on other sites More sharing options...
DAYWALKER Posted December 21, 2012 Author Report Share Posted December 21, 2012 do anybody know any testing that i can do to determine if it is actual the bent rod that is making the knocking noise or a spun bearing. i saw some youtube video that make the same sound that i have and they stated that they have a spun bearing. thank for the reply. Link to comment Share on other sites More sharing options...
prasamin Posted December 21, 2012 Report Share Posted December 21, 2012 whether it's a spun bearing or a bent rod, you'll have to open the block. that's the best way to find out! Link to comment Share on other sites More sharing options...
boxpin Posted December 21, 2012 Report Share Posted December 21, 2012 Was that my video? The reason I knew is because I had dropped the pan and saw it. Plus it was an N/A and pretty unlikely that it was a bent rod. Link to comment Share on other sites More sharing options...
DAYWALKER Posted December 21, 2012 Author Report Share Posted December 21, 2012 can i just drop the pan and take a look or i have to remove the head too. Link to comment Share on other sites More sharing options...
Zappo Posted December 21, 2012 Report Share Posted December 21, 2012 A spun rod bearing will have a random knock at idle. When you rev it, it will be a constant knock, but will go away as the revs come back down until idle, then random again. Bent rod will be like a bad lifter, only louder. If you have metal flakes in the oil, it could be either, but more likely a bearing. My spun bearing didn't sound as bad as this, http://www.youtube.com/watch?v=yQqLgGRhW84&feature=player_embedded Link to comment Share on other sites More sharing options...
volvoguy23 Posted December 21, 2012 Report Share Posted December 21, 2012 Op how do you think this happened? Link to comment Share on other sites More sharing options...
DAYWALKER Posted December 21, 2012 Author Report Share Posted December 21, 2012 yeah the video i watch was boxpin video. why is zappo and boxpin video sound different but both claim to have bad bearing. mine sound like boxpin a constant knock that is louder than a valve lifter. boxpin are you sure it is a bad bearing? if it is the bearing i will just need to drop the pan and replace the bad bearing but if i have i bent rod. i have to pull the head and upgrade the rod. Link to comment Share on other sites More sharing options...
boxpin Posted December 21, 2012 Report Share Posted December 21, 2012 You tell me. http://www.youtube.com/watch?v=MGfYk9fa3lg Link to comment Share on other sites More sharing options...
Zappo Posted December 21, 2012 Report Share Posted December 21, 2012 My bent rods sounded like his video; very constant knock that got way louder when the engine was rev'd up. Spun bearings are usually caused by lack of oil. The video I posted is of Danny's car when he spun a bearing. Link to comment Share on other sites More sharing options...
DAYWALKER Posted December 21, 2012 Author Report Share Posted December 21, 2012 thanks for the quick reply guys. i guess i have a bent rod than. damn this suck. i got ard green tune for my car and i thought it was going to be safe. it was my fault though. i should let off when i felt the two misfire before the knocking sound. this is a dumb question but i have to ask. how long can i drive it with a bent rod? the car still drive really good but with a bad knocking sound. Link to comment Share on other sites More sharing options...
Zappo Posted December 21, 2012 Report Share Posted December 21, 2012 I bent all 5 of mine at the track due to an overboost issue and drove it 100 miles on the freeway after that. I had no block damage, but at the time we didn't think it was a rod either. Others have made it a mile or two and punched a rod out the side of the block. I say you have damage for sure. Pull the pan and inspect it to be sure of what it really is. Bearing is quick to test since the rod will be loose on the crank. Bent rods can be a little hard to see, but look for a curve near the top at the piston. Link to comment Share on other sites More sharing options...
BurgerBob Posted December 22, 2012 Report Share Posted December 22, 2012 Spun Bear: Link to comment Share on other sites More sharing options...
Yea-but... Posted December 23, 2012 Report Share Posted December 23, 2012 /thread Link to comment Share on other sites More sharing options...
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