Unknown engine noise help

[SirRobyn0]

The thing that makes this a little harder is your exhaust. What I mean is your exhaust on the video at least sounds pretty loud, which covers the noise considerably. I would have bet on water pump until you said it did it with the fan belt off. I'd say test it again when you have time. Remove the fan belt, test. Remove P/S belt test again. If the noise is still there try to isolate generally where it is coming from, as in front of the engine or back. Noises can travel in weird ways sometimes and this might require carefully getting under the engine or above it with engine running. This is NOT going to be coming from rod or main bearings. It really sounds like accessory noise, but if it's not something belt driven then I suppose it's possible it could be something from under the timing cover maybe possibly the oil pump. Let us know what you find when you do more work on isolating it.

 

[78C10BigTen]

The thing that makes this a little harder is your exhaust. What I mean is your exhaust on the video at least sounds pretty loud, which covers the noise considerably. I would have bet on water pump until you said it did it with the fan belt off. I'd say test it again when you have time. Remove the fan belt, test. Remove P/S belt test again. If the noise is still there try to isolate generally where it is coming from, as in front of the engine or back. Noises can travel in weird ways sometimes and this might require carefully getting under the engine or above it with engine running. This is NOT going to be coming from rod or main bearings. It really sounds like accessory noise, but if it's not something belt driven then I suppose it's possible it could be something from under the timing cover maybe possibly the oil pump. Let us know what you find when you do more work on isolating it.

Yes my exhaust is very loud, its headers and 3" pipe to flowmasters but i thought the video caught the noise very well. It does sound like the very front of the engine.

 

[78C10BigTen]

I have another short vid of the noise that i took right before i removed the belt but im not sure you can hear it

 

[Scotty D]

How old is the timing chain?
Hopefully it’s not the chain rattling against the front cover, unfortunately I had that happen, wasn’t pretty.

 

[78C10BigTen]

How old is the timing chain?
Hopefully it’s not the chain rattling against the front cover, unfortunately I had that happen, wasn’t pretty.

Honestly i couldnt tell ya.... supposedly this motor came from a stock 76' (i believe) idr exactly, my gf found it on FB when my motor blew. I do remember the guy tellin me it came outta his grandpas stock truck when it rotted out.

 

[bucket]

How old is the timing chain?
Hopefully it’s not the chain rattling against the front cover, unfortunately I had that happen, wasn’t pretty.

It does sound like a chain type of noise. But I've never heard a small block or big block timing chain make noise.

Even this thing was silent right up until it failed:

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[SirRobyn0]

I can hear the noise in the video don't get me wrong, my only point was if you had happen to have a quiet single exhaust the noise would sound so much louder, there would be less exhaust noise interference and it would be easier to pick out subdued tones in the noise. I really can't image what in the front of the engine would a noise like that, other than the belt driven stuff. At the shop we'd remove the belts one by one, the only time I haven't found a noise like that by removing the belts has been on timing belt driven engines, obviously that's not the case here. Also I like to use a long section of heater hose for a listen device, of course be careful. And no I've never heard a chev V8 timing chain make noise, but there is always a first. Let us know what happens next.

 

[Scotty D]

When my chain went, it started that morning on the way to work, went out for lunch and when I went to start it up is where it went boom! Literally, with a backfire and that was it, pulled it apart to find a toothless gear and the front cover ground up from the chain beating on it.

 

[legopnuematic]

Check the fuel pump, the one on my 76 the pin wasn't being retained int the casting and was causing a rattle/click. Pump was not very old either. It would stop sometimes, then start making noise again. One picture is of the bad pump, other is of a good one.

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[79dentside]

Any update on the noise? I would check the front accessories with a stethoscope first (being careful not to put it on anything moving of course).

This is not a Chevy in this video, BUT I had a TERRIBLE knock/and or whine depending on the day that would go away once it warmed up. It ended up on my car being an alternator. It was extremely loud and would go away completely.

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I thought I had severe engine issues/or timing chain tensioner leak down problems.... A stethoscope revealed my awful noise. Check the easiest things first!

 

[78C10BigTen]

Ive isolated it past alternator by running it without the belt. It still makes it intermitently and i have not got time to go further into it.

 

[79dentside]

Ive isolated it past alternator by running it without the belt. It still makes it intermitently and i have not got time to go further into it.

Them stethoscopes are great little tools, I love mine. Good luck finding it, I hope it’s nothing major.

 

[78C10BigTen]

Them stethoscopes are great little tools, I love mine. Good luck finding it, I hope it’s nothing major.

I also did try the long screwdriver to my ear trick but came up with nothin

 

[Doppleganger]

If we're playing Match Game, I'm going with bearing.

 

[78C10BigTen]

I also took a good look at the pulleyes while it was runnin and they all seem good and square, no wiggle or nothing so cant be there either