loud knocking sound

[scooter122983]

I took my truck out last friday and halfway home the engine sounded like it wanted to blow up. I limped it home it had good oil pressure so I dont think I broke a connecting rod. I checked the pushrods and adjusted the rockers to take up some slack. Then one day it stopped making the noise. The day after that it started back up again making that noise. The best way to describe the noise is like someone hitting a engine block with a hammer. The sound is also consistant with engine speed not vehicle speed. The truck is a 90 K5 350 tbi 700 tranny and 241 case. I need help because i will be out of work for about 10 days and i need something to fix.

 

[Xtremegmc80]

maybe flywheel cracked? , torque converter bolts got loosed? anything external loosed? if not then remove oil pan.. first check everything outside of engine to see if anything got loosed or bad...

 

[tumbleweed1002]

Dose the noise speed up with engine rpm if so it sounds like you might have lost a rod bearing.

 

[35dp]

the other day a freind had this problem and we thought it was a bearing, it turned out to be a warped flywheel. it was hitting the transmission housing. also might want to check the harmonic balancer. just trying to help. Dustin

 

[wicked jester]

check the flex plate for cracks, my '88 did that, went crazy looking for the noise as it was just after a rebuild, turns out the flex plate had cracked around the bolts on the crank.

 

[dyeager535]

Check for loose bolts...flywheel, balancer, pulleys.

 

[scooter122983]

Thanks for some leads i will check those this weekend and next week. I suppose it would be a good time to throw in a better converter while i have it apart.

 

[Mudstud]

Put a wrench on the bell housing bolts too. Good luck