olds 307 knocking?

[ERIC87442]

Haven't done much with it lately. But i did take a recording of the sound and showed my boss at work (he use to build a lot of race engines) he thinks i wiped a cam lobe or possibly broken push rod, rocker, lifter maybe. Something in the valvetrain. This weekend im going to do another tear down but of the upper end and do some inspecting. Being colder out now the noise is much louder. Knock at idle. Holds through when you rev. And still there back at idle.

 

[ERIC87442]

Somebody humor me, a cracked flex plate noise would go away with removing the torque converter correct?

 

[ERIC87442]

95% sure its the lifters. I pulled rocker arms and pushrods on 8. Noise still there. Removed 6. Noise went almost away, Still very very faintly there though. Shut it off and it sounds like something rattling faintly

 

[85olds]

Did you actually remove the flex plate to inspect near the bolt holes? if not, some times you can pry it forward and backwards,side to side while some one holds the crank still,listen for slight ting noise or any movement...

does the engine back fire or miss generally with a tapping sound would lead me to look at valve train (could also use a vacuum gauge to see if the needle jumps indicating valve train issues.(bigger cam in engine can mislead vacuum test)

with push rods out the lifter have no way to move back down and ride on the cam, making noise, still could be a collapsed lifter ?!!

 

[ERIC87442]

I didn't remove the flexplate. I did pry on it. I pulled the rockers, pushrods, and lifters out. I dissasambled a few lifters and found everything intact. I dissasembled 4. Intake and exhaust on 8 and on 6 the ones from 8 popped up upon removing the clip. The ones from 6 did not i had to tap them a bit to get them apart. Thats the only thing i seen different. I am going to replace all of them. My guess one or two wernt priming propperly. I inspected valve springs and nothing was broke.

 

[ERIC87442]

Thought i was on to something. Guess not. Its narrowed down to cyl # 6. I cleaned all my lifters and inspected. I get more oil in the heads now. But the noise is still there. Heres what i did. I removed the spark plug wire from cyl # 6 and the noise was gone. What do you suppose that means?

 

[techg8]

Thought i was on to something. Guess not. Its narrowed down to cyl # 6. I cleaned all my lifters and inspected. I get more oil in the heads now. But the noise is still there. Heres what i did. I removed the spark plug wire from cyl # 6 and the noise was gone. What do you suppose that means?

means its a #6 rod knock most likely or a wrist pin possibly.

 

[ERIC87442]

Thats what my thought... i paid to have the bottem end checked out already too....

 

[ERIC87442]

I never did update this. I tore it apart again and found a melted piston on cyl 6. That was my knock.