So sorta a long story here @Jorvis79 had his 400 rebuilt last year we put it in and it ran great . He drove it to Syracuse for the nationals from Albany (2.5 hr drive) no issues drove around out there no issues all was good. Then on the way home he said he heard a whinning noise as he described it but the truck ran fine, oil pressure fine other than noise everything was good. I an idiot didn’t go listen to it, instead listening to his description said must be the original ps pump that was in it he was going to order cvf serpentine system anyways so I said just order it and after it’s on it’ll probably be fine, we’ll installed it and it’s still there, now that I’ve heard it it sounds like a bad bearing in a mower spindle is the best way I can describe it, I did manage to get it on film, I pulled the valve covers and oil pan off and there’s nothing obvious there. Before that I removed the belts and started engine with no accessories spinning noir still there, was hoping someone out there had an idea what it could be or a place to look, he’s going to stop by engine builder on Monday but I figured it couldn’t hurt to start here first if anyone recognized the sound or had an idea

thanks

 

This is the video

 

That's a tough one, since you've eliminated everything exterior that helps.

Does it get better or worse with RPM, load or deceleration? it doesn't sound like top or bottom end to me. more like a timing chain or something. sort of a spark knock sound but it seems to be running really well, if you retard the timing a little does it change anything?

If you spin the filter off and dump the oil out where you can look at it good that would tell you if you're losing a cam or a bearing. if it's clean you can spin it back on. but I doubt that's it.

 

It’s does go with the rpms, oil and filter is new but when the old was drained it went through a screen to make sure everything looked good and no metal, chain and such is new no guarantee with todays crappy quality parts, I didn’t try to retard it, it’s set to 10 Btdc, factory spec but if builder doesn’t have any ideas to look for inside I’ll throw pan and valve covers on and try retarding it before we do anything else, thanks

 

AC idler pulley, water pump.

 

makes the noise with no drive belts on, but thank you

 

Water pump can do that

 

Is it a manual transmission?
I now have a similar noise from my 400 after a long trip on a newly built motor. I'm thinking my noise is the pilot bearing but not sure yet. I removed all the belts and the noise is still there. Oil and filter were clean. And it runs great. I've been driving it still on shorter trips and it hasn't gotten any worse. Started hearing it on the Monday after mother's day after driving it an hour and a half each way to see my mom.

 

No its a c6, keep me updated though if you find anything and if we get an answer I’ll be sure to put it on here as well

 

A pilot bushing won't make any noise unless the clutch is depressed.

Torque converter or flywheel bolts rubbing or loose could make a noise like that.

 

440,,
I am not a engine builder or guru.
Just asking, could it be the FP ecentric bolt backed out of the cam shaft
Could you remove the fuel pump to see if the noise changes.
In my years, I have heard plenty of rods, mains, crank shaft thrust noises but to me this does not sound like that.

 

I had thought of that too, and that would mean the cam gear is going to get loose also. it would be possible. the aftermarket distributor could be going sideways too.

I agree it doesn't sound like a typical internal noise. a wrist pin drifted over to the cylinder wall possibly, I don't remember if 335's are press fit or has clips.

 

335 is press fit. THat sound seems to me like something in the bellhousing area. maybe remove starter, and listen after engine is running of course, maybe transmission issue, torque converter? flex plate cracked?

 

Well got her all back together noise still there, so at this point at a loss for words I think this video you definitely hear it better but so far pulled trans back made sure flexplate looked ok and bolts tight, starter ok, all belts in front removed to eliminate them -noise still there, swapped carbs, distributors/ no change, when moving throttle by hand you can feel it rattle and it sounds loudest to me in the pan(when off no metal pieces nothing loose), so at this point I feel like it has to be internal

 

I can't hear it well enough here ... but I did notice looks like the vacuum hose isn't on the distributor advance can.