Name that knock- Solved

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subcom

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Changed plugs last night and started it up and let it warm up. Everything sounded fine and I turned it off. Was going to go for a drive today when I heard this noise shortly after starting it up. Has good oil pressure and can't see any metal on the end of dipstick but noise sounds kind of deep to me. Eyeballed a couple of the torque converter bolts and they look good. The engine is idling around 700RPMs.
 
Rod bearing? It's clicking awful fast at that RPM. Hard to tell 100 percent from the video where it's coming from.
 
You're right, sounds way too fast for a rod bearing.

Rotor in the distributor cap? Distributor cap loose on one side and leaning over?
 
nm9stheham said:
You're right, sounds way too fast for a rod bearing.

Rotor in the distributor cap? Distributor cap loose on one side and leaning over?
Click to expand...

Sounds lower though doesn't it? With how fast it is thought I really wanna say valvetrain. Lifters? Man I hate trying to diagnose over video lol.
 
Lustle said:
Sounds lower though doesn't it? With how fast it is thought I really wanna say valvetrain. Lifters? Man I hate trying to diagnose over video lol.
Click to expand...
Thanks guys. It sounds kind of deep but the frequency seems too high to be a single rod, unless all eight are bad. Unlikely. It has a definite solid thud to it. I'm hoping it's something up high in the valvetrain or external.
 
well , take a wooden broom handle . place one end on the motor as its running and the other end of the handle tight up against your ear . that will transfer the noise straight up to you . now move the motor end of the handle around on the motor , keeping in contact with the motor to find the place were it is loudest . move the motor end all around the block and head . it will help you locate were and what could be hammering . hope its something simple .
 
How does it sound when you rev it up? Rod bearing will usually increase in noise and decrease when you let off the throttle until it settles down into an idle. I would pull a valve cover and check lifters, rockers and springs first.
 
Sounds to me like a cracked flexplate. Bad fan clutch Cracked fan but not so much as a Cracked flex plate. It seem like a deep sound on the crank.
 
Just a guess because it is a video but sounds like the flex plate mentioned above, or rocker noise. Don't sound like a rod. It is possible it's a piston but you need to rev it up a bit.
 
It's definitely more pronounced down low, oil pan area or further back. I poked around with a long piece of heater hose to my ear and crawling under the car it's definitely much more audible.

Revving it I don't hear that decrease in noise when it settles back to idle. It seems persistent. I also pulled the fan belt and the old mech fuel pump to rule out alternator, water pump, and fuel pump.

I need to rule out flex plate and bolts. I built the motor with a new SFI B&M flex plate and ARP converter bolts, secured with loctite, but something may have loosened up. Oil pressure also holds steady when I lightly rev it.

This sucks but hopefully I don't have to pull the motor. Thanks guys!
 
nm9stheham said:
You're right, sounds way too fast for a rod bearing.

Rotor in the distributor cap? Distributor cap loose on one side and leaning over?
Click to expand...
Checked the distro cap also. Looked good. But never thought of that. Thx!
 
let us know if all 4 of the convertor to flexplate bolts are good
and at some point you may want to connect those PCV valves ;)
 
Sounds like valve train.
 
Could this be spark knock? This all started after changing my plugs. I gapped them a little wider than last time. Going from 0.040 to 0.045. Or maybe just coincidence? Usually you don't get spark knock except under load or at WOT... Just thinking out loud. The damn noise has such a consistent cadence to it, it sounds like all cylinders, all the time. Couldn't be a single rod.
 
Mopar Tim said:
Sounds to me like a cracked flexplate. Bad fan clutch Cracked fan but not so much as a Cracked flex plate. It seem like a deep sound on the crank.
Click to expand...
I had this problem with loose flex bolts and had a similar sound, ethier way its easy to get under the car and look.
 
It was a single loose converter bolt!!! I put about a half turn on it as tight as I could and started it up. Noise is gone! The Mopar gods have smiled down on me! And thank you all for the suggestions!!!
 
I'm using the ARP 12 point chromoly bolts. No washers. I'm pretty sure if I didn't have the dust cover installed I wouldn't have had contact between the bolt head and the cover. The gap between the two is pretty thin.
 
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