irregular loud knock

[Leviathen77]

ok, well it all started when i noticed a slight tick. so i changed my oil and took it for a test drive. after driving about 8 miles i came to a stop and tried going again shifted from 1st to 2nd and then lost 95% of the power i had. and now i have a loud irregular knock. its a 91 gsx i have a built bottom end wiesco pistons eagle rods balance shafts been eliminated. new oil pump with about 1k miles. stock head, t3/t4 turbo full 3 inch exaust from turbo back. and i just installed a act 2600 clutch with unsprung disk. which has maybe 600 miles on it. any ideas? please help.......

 

[LiquidX]

If you can get a audio clip of the noise that would be great and if you can also locate the region where the noise is coming from.

 

[Leviathen77]

ill work on an audio clip. its weird. it sounds like the head but it sounds like the block 2. but i can feel it through my clutch pedal also. im stumped. ive redone timing about 3 times today. ive looked in the valve cover to see if anything looks loose or messed up. when i lost power...... the timing did jump. but it runs 2 good for (except for the knock) for something to be bent. here in a few ima go check compression. but ill try and get the audio clip maybe even video if itll turn out

 

[DeadsEvolution1]

When I spun a rod bearing in my old laser the car ran just fine and boosted like normal. But when at idle or something I could feel it in the clutch pedal or when rev'd the engine it would knock loudly. Drain your oil see if there are metal shavings at the bottom of the pan and/or the bottom of whereever you drain your oil into.

 

[Leviathen77]

thats the thing tho. the car idles fine but has no power. this weekend ima tear it all apart. im thinkin it may have something to do with my clutch that i installed.

 

[jimbob_843]

Yeah that sounds to me like a spun bearing. Did you notice the noise after hitting high rpms or did you not have hardly any oil? The easiest way to tell is to drain the oil in a pan where you can check to see if there are any metal shavings/flakes. If you have metal shavings then you might as well drop the oil pan and pull off a rod cap and see the damage thats been done and pray that the crank isnt scarred(most likely will be). Good luck and keep us updated.

 

[Leviathen77]

i always keep the oil full and yea. but cyl 4 spun a bearing. scored the crank. but thank god my rods fine anyways i suppose i should have replaced all bearings before i put this block in. i have another block with under 100k miles with a good crank. so ill ###### just switch the cranks out. but heres the question now. should i use acl bearings when replacing or should i go with the clevite 77? which is better. the acl i was looking at have a coating thats supposidly awesome. but i know of people useing the clevite with no issues. inputs welcome. thanks

 

[smrogers5771]

Did you balance your crank when getting the engine rebuilt? most people dont realize what this can do.. your crank will flex like a pretzel if not properly balanced and throw either a main or rod bearing.... im sure its a rod bearing you are hearing..


Whoops NVM ya found out ya had a bad crank... I always used Clevite 77's..... but after about 10,000 miles I had to replace them for low oil pressure.... so I duno if it was my crank or if my bearings were shot...