Internal engine noise

[pjfellhauer]

Video of engine

from what we have diagnosed its not anything ran off a belt or the mechanical fuel pump, my uncle thinks it could be a loose timing chain, front harmonic balancer flywheel thing, or the oil pump but curious as to what other ears have to offer.

All fluids are normal and it seems to be running just fine besides making an awful noise, gonna do a compression check before I tear down into it, have a feeling it could be a bad bearing as well but

Any help appreciated!!

1978 Chevy Bigten

 

[75gmck25]

Pull both valve covers and check for loose pushrods and rockers. Adjuster nut may have loosened up and the pushrod is bouncing against something.

 

[pjfellhauer]

Will be one of the first things I was gonna check, working on it tomorrow, will update. I trust your ears! Lol

Thanks!

 

[Smtty58]

Pull the distributor cap. Rotate the motor by hand until the rotor just starts to move. Then rotate the engine in the opposite direction, and note how much you need to rotate it until the rotor starts moving. This will give an indication of how much wear is in the timing chain, in case that noise is the chain rubbing on the cover.

 

[Steelbuddha]

Pull both valve covers and check for loose pushrods and rockers. Adjuster nut may have loosened up and the pushrod is bouncing against something.

It sounds top end/valvish to me, too. (From a few seconds of video, anyway.)

 

[Steelbuddha]

Get yourself a mechanic's stethoscope and home in on it before you start disassembling. This one is so cheap I decided to refresh my 45-year-old one: https://www.amazon.com/dp/B0D91VMQR6/

 

[Ricko1966]

Pull the distributor cap. Rotate the motor by hand until the rotor just starts to move. Then rotate the engine in the opposite direction, and note how much you need to rotate it until the rotor starts moving. This will give an indication of how much wear is in the timing chain, in case that noise is the chain rubbing on the cover.

^^^ when you do it though, stop with your crankshaft timing mark as far after TDC as your timing scale goes. Now see where you are at on the scale. Write it down,now when you turn counter clockwise. When the rotor moves look at the timing scale. 8° movement put in a timing set just as maintenance if nothing else. 6° movement think about a chain in the near future.

 

[Smtty58]

Thanks Ricko for adding that. I couldn't remember the go/nogo specs.