Help diagnose knocking issue VIDEO

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gdizzle

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I am experiencing a loud rattle/knock which seems to occur at a specific RPM (maybe 1500-2000), then fades. Also it doesn't appear to be an issue at idle. Happens when I drive it as well.
I dont recall hearing this, until recently when I changed out all wires, cap, rotor, spark plugs, belts, water pump, and oil change.
Note I have only had this car for 6 weeks.
Would you give it a listen and see if you can give me any direction on how to fix?

Also I just adjusted the valves, most were fine, a couple of the Intake needed to be tightened.

[ame]https://youtu.be/cuDIvNJ26gg[/ame]
 
Get a long pry bar out and start putting it on things around the front accessory drive and put your ear on the handle. That will show you where it is. If not there try different places on the side of the block.
 
It is a brand new water pump. i sure hope I dont have to remove it again. I will remove the belt and rev it up.
I did notice that when I installed the pump, there wasnt very much distance from the impeller to the sides on the water cavity. But I thought it cleared when I spun it.
 
Seems like the water pump. The WP pulley seems to move forward as the revs increase.

Is it a rebuilt/remanufactured water pump? I haven't had good luck with remans. They seem to fail for the same reason they failed the first time
 
it is not the water pump, and it is not the fan. and it is not the timing. Other ideas?
 
Flexplate was tight. Not sure how to inspect the flywheel. It looked fine. Infact it was painted a dark green?

Gonna try a compression test today, maybe it will tell me something?
 
Try pulling one plug wire at a time. If the sound changes, it's probably internal. Rod or wrist pin. When you changed the oil, was it really thick? Could be the previous owner dumped some motor honey in there to keep it quiet.
 
When I first listened at a low volume setting it almost sounded as though it were dieseling. I realize you've said it's not timing but does the timing mark advance steady and hold at the rpm when making the noise?

How does your oil look off the dip stick?

What psi oil pressure do you have?

Do what MRL says.
 
Try pulling one plug wire at a time. If the sound changes, it's probably internal. Rod or wrist pin. When you changed the oil, was it really thick? Could be the previous owner dumped some motor honey in there to keep it quiet.

Yes. Very easy to do the spark plug pull test.

This got me a new stroker motor! Yay! :banghead: :cheers: #-o :burnout:]


Sound familiar ?


[ame="https://www.youtube.com/watch?v=gdAm4_RvueI"]340 Rod Bearing gone bad - YouTube[/ame]


[ame="https://www.youtube.com/watch?v=DbT2wgT4puA"]340 rod bearing gone bad #2 - YouTube[/ame]
 
thanks for the great replies guys. Ok I tried the pull one plug out, each time I heard the engine drop a little, then I would go rev it to that point where the noise comes in. It was the same for each plug.
I dont get the knocking when at idle. It is only as the engine gets up to a certain RPM, then it gets real loud, then if I keep going past it, the sound goes away.

the oil was pretty dark and thick. sounds loudest at the rear of the engine, toward the bottom end.
My compression test seems to show #5 is low 100? all the rest are between 120 - 135.

I am still not real sure what any of this means, except I have begun to price a complete engine rebuild, which seems to be costing about the same amount I just paid for the car 8 weeks ago. sigh....
ideas?
 
Did you rev it until it make the noise, then pull the plug? For each?

You are looking for a difference in sound while it's making the noise.

A mechanical oil pressure gauge test like was mentioned above could be helpful.
 
Thanks for the feedback. Do you have any links or info on how I can test the oil pressure like you mention? I did just replace the oil pressure sensor. Is that where you would test it?
I also just remove the PRV but it seemed fine.

any help is appreciated.
 
Yes, just screw in a mechanical gauge instead/where you screwed in the oil pressure sensor.

Here's a dedicated oil pressure test setup at Harbor Freight: http://www.harborfreight.com/engine-oil-pressure-test-kit-98949.html

There is one screw into my motor in those videos also.

Here is one is just at the back of the lifter valley on my motor. Just some brass fittings in the same place you put that oil pressure sensor in.
 

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If it made no noise prior to the tuneup, I also believe it is likely the ignition timing. Sure sounds like it. Not rhythmic enough for a typical rod knock, but possible. Have you tried to twisting the distributor to make the sound worse? Play with th point gap, if so equipped? Good luck.
 
Yeah I've heard that noise about 4 different times. Slant sixes are indestructibllllllllle. Yeah...RIGHT. Sorry, that's a rod bearing.
 
The sound is like a very loose timing chain slapping the inside of the timing cover, but a bit low toned for that, and the engine is running pretty steadily. Does not sounds much like a rod bearing; too erratic, too rattley, too rapid, and not regular enough. But if lower and further back, then I would first go for a loose flywheel or flex-plate bolts, a bad piston pin, cracked piston skirt, or possibly a cracked crankshaft. The regular tapping sounds like an exhaust leak, burned valve, or a valve not seating well.

There are a number of things to check with the engine in the car.

1. Pull the bottom transmission inspection plate and check carefully in there. Look for any looseness of the flexplate/converter, or flywheel.

2. Put a bolt into the threads inside the crank snout (3/4" x 16tpi x 2.5long, with flat washer), or use the fan and belts, to turn the crankshaft back and forth, with the distributor cap off and watching the rotor. It out to reverse back and forth with very little movement of the crank if the chain is tight; if not, and the rotor does not turn for some number of crank degrees when you reverse the direction, then the chain is worn and slack. You can observe the number of degrees of slack from the timing scale. More than 4-5 degrees indicates the chain is getting to or beyond service limits.

3. You can check the thrust bearing by pushing and pulling on the crank pulley; it should move only about .010" or less.

4. I would also double check the crank pulleys and damper.

5. Have you checked this with ALL of the belts off?
 
Flex plate to crank bolts are lose engine pulses rock the converter back and forth .
 
Per another thread he checked those and ruled them out.

What you could do to eliminate extra work checking things to confirm them or rule them out is simply continue driving. If it's a loose bolt, it'll fall out. If it's a loose timing chain, it'll break or fall off. If it's a spun rod bearing, it'll sieze, snap the rod and send what's left through the side of the block.

Then, you can come back and notify whichever person had the correct guess.
 
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