Time to play ... Name that Noise!

[cshanek]

I noticed coming home last Friday in my 64 C20, that she would go in and out of a loud diesel sounding noise (seriously sounds like a large diesel engine) coming from under the hood. I was fortunate enough to have experienced an engine knock from my POS Neon about 20 years ago, and this noise certainly isn't that loud or pronounced, though it does sound a little too loud/thump-like to be a lifter tick. The noise comes and goes at all RPMs, with or without me applying gas, and in every gear. Sometimes at red lights, sometimes while driving. It usually last for 1-3 minutes or so. I recording the transition (at about 13 seconds) from "diesel" noise to standard tonight after letting it idle in my garage for about 10 minutes. I should also mention I put a bunch of 10w40 in when I got it home after buying it, because it was completely dry, and that was all I had at the time. Any thoughts?

For now I plan on trying Rislone and/or Motor Medic, changing the oil filter and filling her up with 10W30.

https://drive.google.com/open?id=0B6...2pIeVNpcnpybGc

[TopFuel1966]

Sounds something like piston skirt slap.

[shp4man]

I'm not liking the "completely dry" oil part of the story. Which engine is it?

[53lowdown]

Sounds like lifters/rocker arms - I'd like to know what your oil pressure gauge was reading. If you were that low on oil you were probably intermittently losing oil pressure and intermittently the hydraulic lifters were running dry.

[cshanek]

It is a 283. I only recently (bought about 2 months ago) noticed this noise come and go.

[shp4man]

The thing with engine noises is they usually aren't intermittent. When it's making the noise, does it change with engine load? Like louder, or a double tap instead of a single tap? Does it run rougher?

[cshanek]

It's very intermittent yes, it does get louder as the engine gets louder, higher RPMs before shifting, but I do not notice any loss of power or other change in how the truck runs when it makes the noise.

I will try to get a high quality recording tonight, since the one I posted really doesn't do it any justice. The engine noise easily drowns out the normal operational noise.

[cshanek]

Originally Posted by TopFuel1966

Sounds something like piston skirt slap.

I watched some skirt slap vids and yes it does sound very similar (https://www.youtube.com/watch?v=Wbwkz9833eg) though it gets a bit more "knocky" at high RPMs. Any idea why it would come and go?

[cshanek]

Originally Posted by TopFuel1966

Sounds something like piston skirt slap.

Another curiosity about the piston slap idea ... doesn't that usually get better as the engine heats up and the skirt expands? Mine does not make any noise until the engine is warm, and then it comes and goes.

[geezer#99]

What carb?
What distributor?
Where's vac advance hooked to? Ported or manifold source?
What's your initial timing?

[shp4man]

Grab the fan and try to shake it back and forth. Possible water pump issue?

[cshanek]

Originally Posted by geezer#99

What carb?
What distributor?
Where's vac advance hooked to? Ported or manifold source?
What's your initial timing?

Don't know yet on all of these things. I just got the truck about 8 weeks ago and have not gotten that far (or needed to yet) under the hood.

[cshanek]

Update:

So I decided randomly to check my oil again last night during my 15 mins of free time, and the dip stick was dry again. I leak a little bit nightly in the garage ... something to the tune of 1-2 inch diameter spot on the garage floor, but certainly not quarts, so I guess I am burning oil, which might explain a little bit of smoke I get when I stop at lights. I still do not know what part is causing the noise, but I would imagine low/no oil could have something to do with it. Perhaps cracked rings is causing me to burn oil?

[63C20]

piston slap or wrist pin slap , usually a wrist pin will get a diesel sound

[The Rocknrod]

Mine sounds something like Brrrrrrrrr, tink...wham.

[cshanek]

So I filled her up with Oil again, added some Rislone, and ran her for about an hour, and she was just purring like a kitten. Unfortunately I am leaking a little oil (see pic) and probably burning a lot, so I will be doing a compression test sometime this week and hopefully it will just be a head gasket issue.

[andyh1956]

Check the right side of the timing chain cover to see if a worn chain has rubbed thru the cover & is leaking oil.
As to the noise, IF you have a lifter intermittently collapsing on an INTAKE valve this could be the "Thump" you describe. If the piston starts down on an intake stroke & the intake valve don't open at the proper time the piston will generate a higher than usual negative pressure, and when the valve does open late, the resulting rush of air will "Hit" the piston & cause a "Thump". This phenomenon is more prevalent on diesel engines with worn cam lobes than gasoline engines though.
What does the correct answer win?

[TJ's Chevy]

Ya'all wanna hear what toasted lifters sound like????

Meet my 292 I6 gas version of a cummins!

Recessed valves and 95 psi compression, but Man she pulled hard with that 4 barrel! Had 15w-40 in this vid.


Skip to 1:27 for clatter.
https://www.youtube.com/watch?v=0H6MOkFshSU

[cshanek]

Originally Posted by andyh1956

Check the right side of the timing chain cover to see if a worn chain has rubbed thru the cover & is leaking oil.
As to the noise, IF you have a lifter intermittently collapsing on an INTAKE valve this could be the "Thump" you describe. If the piston starts down on an intake stroke & the intake valve don't open at the proper time the piston will generate a higher than usual negative pressure, and when the valve does open late, the resulting rush of air will "Hit" the piston & cause a "Thump". This phenomenon is more prevalent on diesel engines with worn cam lobes than gasoline engines though.
What does the correct answer win?

Winner gets this:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[cshanek]

Originally Posted by TJ's Chevy

Ya'all wanna hear what toasted lifters sound like????

Meet my 292 I6 gas version of a cummins!

Recessed valves and 95 psi compression, but Man she pulled hard with that 4 barrel! Had 15w-40 in this vid.


Skip to 1:27 for clatter.
https://www.youtube.com/watch?v=0H6MOkFshSU

Wow, I recognize that sound ... exactly like mine when it does its thing. Now that I have oil lifter noise is gone, but every now and then I get a little pop you like you do. Mine is at about 85k miles.