When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
While I'm thinking about it I'll ask another question. I hear a sound in my engine when it's idling. It sounds like someone has a few of those big marbles and rolling them around in their hand. I can't hear it (if it's even there) when I rev her up but as soon as I let off the gas, there it is. What do you think it is?
I think it's the cam/lifters not getting along. I think the cam has wore down prematurely. I intend to change the cam but it'll be a few more months. It's not coming from the front.
Sorry, most time people say marbles I think main bearings - and you hear them down low but the sound goes away as the rpm goes up do to better oil pressure.
I cut the handle off an old broom and use it to listen to knocks - hold one end against the bottom of the block and the other against your ear - or just behind the ear. By moving the stick around the engine you can find where the knock is loudest - and from that come up with a better guess as to cause.
If the noise comes from down low on the block I would drop the pan and plastagague (sp) the mains.
Thrust bearing?? The crank is walking back and forth "knocking" on the center main. When you rev it up it is forced forward and the noise quits. Once you let it idle it will then start rocking.
Put a close eye on the balancer and rev it up quickly a few times. Do you notice it moving back and forth?? Turn off engine and put pry bar on balancer and put pressure forward and backwards....it should BARELY move, it you can make it thunk then that's the issue. It will continue to try to destroy itself the more you drive it.
Debestus, take all the belts off and listen to it again. Does it have a certain pattern to it? Does it go in time with the engine, half-time with the engine? Run the engine with one spark plug disconnected at a time and see if one of them makes a difference. Main bearing noise is pretty deep sounding, rod noise is higher and more metallic. You can hear rods pretty good when deaccelerating. I guess I don't know what marbles rolling around sounds like, was thinking more of a continuous gravel like sound of them rubbing together.
Perhaps the term "marbles" is not the best one to use - to many of us that term means something serious on the bottom end.
But don't worry, before you do real expensive damage that knock will be setting your teeth on edge - unless you are racing your engine.
For what it's worth, the sound is like some big marbles in a sock, no scraping, just some bumping against each other. Tommorrow I'll try the prybar thing and check the crank as well as pull spark plug wires. I'll be honest, I didn't know how to break in a cam when I installed it. Is it possible that the lobs wore down some?
Not an expert on cams either - but I really don't think so. It is possible that your valve lash needs adjusted - if you do not have adjustable rockers you will have to spot the one that is loose and put a longer pushrod in.
Like I said, use a stick to listen to the knock and see if you can trace it back to the source.
I took the water pump loose-change. I took the spark plug wires off one at a time-no change except it got quieter for #5 (uh-oh). I video taped the motor running w/sound. As soon as I can figure this thing out I'll put it on.
I crawled up under the truck after she got warmed up and heard some stuff from the bottom. I can't distinguish yet whether it's the headers leaking or from inside the motor. It's not a deep knock, more like ticking. I know the crank was put in right. That marbley sounds kinda coincides with the engine's loping. I took out today and you can't hear anything but rumbling when you decelerate, sounds like it should.
I know your gona laugh at this, but I had the same sound, was realy loud at startup, found the sourse . it was that stuped driver side exaust manf Heat flaper thingy. I wired it up so it wouldnt move ( in to open possition ) and no more noise. Maby something as simple as that.
Edit: nevermind I see you have headers, well maby someone else with stock exaust might read this. :P