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Discussion Starter #1
Hi guys. Can't seem to understand this one. I still have a random noise that sounds like large marbles bouncing around somewhere in the engine bay. It goes up and down with acceleration. The noise is not present 85% of the time, but when it does come around, it will do it cold or hot, and I can hear it from inside the car if I'm close to a wall like at a drive thru.

Car starts right up, oil pressure is good running and at idle, and throttle esponse is great. I swapped out the PCV, which I thought was the culprit, but the noise came back. Almost sounds like its coming from the valve covers, but I pulled the covers, adjusted the valves, and I don't hear it when I use my broom stick stethoscope.

I will say that the last time that I heard it at idle when hot, I 'thought' that I felt it choking the idle very slightly. I was thinking of changing the oil and adding some of the mystery oil to it.

Any thoughts? Thanks!
 

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Hi guys. Can't seem to understand this one. I still have a random noise that sounds like large marbles bouncing around somewhere in the engine bay. It goes up and down with acceleration. The noise is not present 85% of the time, but when it does come around, it will do it cold or hot, and I can hear it from inside the car if I'm close to a wall like at a drive thru.

Car starts right up, oil pressure is good running and at idle, and throttle esponse is great. I swapped out the PCV, which I thought was the culprit, but the noise came back. Almost sounds like its coming from the valve covers, but I pulled the covers, adjusted the valves, and I don't hear it when I use my broom stick stethoscope.

I will say that the last time that I heard it at idle when hot, I 'thought' that I felt it choking the idle very slightly. I was thinking of changing the oil and adding some of the mystery oil to it.

Any thoughts? Thanks!
Is your ignition timing possibly over advanced causing your knock?
 

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Discussion Starter #3
Is your ignition timing possibly over advanced causing your knock?
I don't think so. I'm currently at 10 degrees BTDC, and the car starts right up and shuts down with no issues. Temp is 185 all day long.

Would rod knock be constant or could it be random? I thought perhaps as the engine reached operating temps, the oil thins out, then one would hear the knock, but the knock is random, even with a warm engine.
 

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Hi guys. Can't seem to understand this one. I still have a random noise that sounds like large marbles bouncing around somewhere in the engine bay. It goes up and down with acceleration. The noise is not present 85% of the time, but when it does come around, it will do it cold or hot, and I can hear it from inside the car if I'm close to a wall like at a drive thru.

Car starts right up, oil pressure is good running and at idle, and throttle esponse is great. I swapped out the PCV, which I thought was the culprit, but the noise came back. Almost sounds like its coming from the valve covers, but I pulled the covers, adjusted the valves, and I don't hear it when I use my broom stick stethoscope.

I will say that the last time that I heard it at idle when hot, I 'thought' that I felt it choking the idle very slightly. I was thinking of changing the oil and adding some of the mystery oil to it.

Any thoughts? Thanks!
You should not have to think about changing oil, its cheap, Change it and filter and look at oil for any heavy metal, If you can , cut open the oil filter and look at the paper wrap.
 

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Discussion Starter #5
You should not have to think about changing oil, its cheap, Change it and filter and look at oil for any heavy metal, If you can , cut open the oil filter and look at the paper wrap.
Yes, changing the oil is cheap. I pulled the plug tonight and there was a small amount of sludge on the magnetic tip with a few hair like pieces that disintegrated between the fingers. Not uncommon. I changed it about 500 miles ago, so I'll use a little mystery oil to see if it cleans it up a bit.

My question was in regard to rod knock. I would assume that rod knock would be a constant if that were the issue, but the noise is random.
 

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Yes, changing the oil is cheap. I pulled the plug tonight and there was a small amount of sludge on the magnetic tip with a few hair like pieces that disintegrated between the fingers. Not uncommon. I changed it about 500 miles ago, so I'll use a little mystery oil to see if it cleans it up a bit.

My question was in regard to rod knock. I would assume that rod knock would be a constant if that were the issue, but the noise is random.
You can do an old school test , if the noise is present at the time, remove one spark plug feed at a time , what you will be looking for is a change in sound. The absence of the spark that causing the combustion "load" to that rod may tell you what you are thinking. If its bad, it will show up .
What kind of sound is this? Deep? Light? metalliac knock or tap?
Do this with the vac advance hose disconnected if you suspect a spark knock. Actually you should not have any mechanical advance until 1500 rpm or so. You will have some advance at idle if hose is connected . If your vac hose is connected to ported vac, you wont have any until throttle plates is opened. Just disconnect the dist advance and go from there to eliminate the spark knock. You can run 10° on the crank.

When you had the valve covers off, did you look for any broken springs?

If you suspect its carbon on top of piston, pour a little LoneStar beer down the carb while the motor is running at fast idle. A little , not enuff to lock up motor. In Texas, this normally will knock off the carbon off the heads. :D
 

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Much as I would like to help, I think you need to post a clip with good audio before anyone can do more than venture a guess.

QUOTE: In Texas, this normally will knock off the carbon off the heads.

Don, what if he is not in Texas?
 

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Are you running a stroker ? 383 ?

The crank has tight clearances at the oil pan and between camshaft/rods.
 

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Discussion Starter #10
Thanks for the responses guys. I will definitely take a quick video the next time that it does it, but its just hard to pin down. I took it out all day yesterday, and it happened once for about a minute, then quieted down again. The sound sounds like something is knocking against the inside of a valve cover, hollow, but not too deep. Nothing looked amiss when I took the covers off (i.e. no broken springs, bent rods, etc.).

Just your typical, mild cam 350 Lawrence..nothing crazy. Although, January may be time to build my first 383...

Not sure about the beer Don...how about a bottle of YingLing or a strong Mai Tai? :D
 

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Timing chain possibly getting a little bit of play and contacting timing cover? If too much play the chain can ride up gear teeth a bit causing contact. Just an uneducated guess on my part.
 

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Much as I would like to help, I think you need to post a clip with good audio before anyone can do more than venture a guess.

QUOTE: In Texas, this normally will knock off the carbon off the heads.

Don, what if he is not in Texas?
Milwaukee best? Buckhorn or Pabst? That other stuff he mentioned, never heard of it. Definitely not from Texas.
 

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Discussion Starter #14
Ok guys. I was able to capture a couple of videos today with the knocking. The first video is from the engine bay, and I don't think that you can hear anything except the wind in the iPhone. This is when the knocking was slight, after the car was warmed up a bit.

http://s30.photobucket.com/user/cv2065/media/IMG_0710_zps21fe836d.mp4.html

This second video, from under the car. Sound seems to be louder when cold, but seems to always be there in some form.

http://s30.photobucket.com/user/cv2065/media/IMG_0712_zps93314848.mp4.html?o=0

And here's a video from the other side underneath.

http://s30.photobucket.com/user/cv2065/media/IMG_0711_zps30af77ce.mp4.html?o=0

I still can't find the noise anywhere with my homemade stethescope. You would think that it would be easy to find? :noway:

Watcha guys think?
 

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Discussion Starter #16
I suppose the oil pump is possible, but I don't hear any knocking with my stick against the pan, just the sound of liquid. Sound is more prevalent from underneath as you can hear in the last two videos. Valve covers are 1/4" higher than stock height. I don't hear any knocking when listening thru the covers or the fuel pump. The sound definitely goes up and down with the throttle and you can hear it standing next to the car when cold, that is, when it's doing it.
 

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Just to eliminate the issue of the oil pump being loaded to much from the dist, could you add an additional gasket the the dist base at the intake, just to make sure. One or two gaskets would be fine, you can glue them both together as a spacer with 3M.


Other than a plugged oil filter by pass or a camshaft walking , tapping the timing cover, that's the only thing I can think of but if it was me, the motor would be out on a stand and apart my morning. I hate these things when you exhaust all efforts and can't find anything.
 

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Discussion Starter #19
Don - Would you mind explaining what you mean by the oil pump being overloaded by the distributor? What is the purpose of the washers? Thanks!
 

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Don - Would you mind explaining what you mean by the oil pump being overloaded by the distributor? What is the purpose of the washers? Thanks!
The oil pump is driven by the distributor , dist is driven by cam gear. Sometimes when blocks have been cut or milled or the intake manifold is setting too low into the area between the heads, the distributor shaft tongue will push down on the oil pump via a shaft.
When this happens, the driving shaft on the oil pump, pushes against the bottom oil pump end plate, many times its metal to metal there when the oil pump drive gear( there are two gears, one idler and the main drive gear). There is suppose to be something like .005-.010 or less between the pump end plate and the drive gear.
Remember the oil pump is a positive displacement pump device. Oil is moved between the spur gears and on to the oil passages.

Now when the distributor sets down too far into the motor, its basically sitting on top of the shaft that turns the pump. The gasket you see under the distributor is basically a sealing gasket, then you tighten the distributor down via the clamp and force the dist down a little more.
Normally this does not bottom out but when it does, it causes the pump to be noisy, especially when oil is cold.
When this is suspected and you have checked everything else, I would pull the dist and remove the gasket, reset dist (does not have to be timed and does need to be reset into the pump coupler).
Look at the dist mounting onto the intake seating flats, if you can see the dist standing up and there is a gap (with no gasket) then determine the thickness of the gasket and decide if one gasket will not allow the dist to stand on the oil pump shaft below.

Make sense? This is not normal but sometimes intakes are not machined properly, especially those china knock off intakes. Normally one gasket , .030 is enough but I have gotten into some issues that required a total of .060, that's two gaskets and a metal shim between.
Sometimes excessive block milling , or too tall of an intake valley sealing ends or too thin intake gaskets cause these problems.
If you didn't build the motor your self, no telling what or where it came from or what was done.

Again, its a simple check, if you can't find any other reason for this noise to be there, you just have to start checking stuff.
Fact you mention you hear the noise at the bottom of the pan, is one clue.

One other thing that can cause the oil pump to be noisy is an oil filter adapter being purposely plugged. This is common for a lot of guys, it forces all oil thru the oil filter , thus the oil pump will labor and if the pump or the pickup tube is touching the bottom of the oil pan, the pan will pick up the noise.

I would start with the dist first, since you don't find anything else above.

Maybe someone else will share some knowledge.
 
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