Diagnose type 1 engine sound - marbles rolling around

[scrivyscriv]

1641cc type one in a bus, about 10k miles on it since I rebuilt it last year.

I just noticed a sound like marbles rolling around, loudest on the left side by the #4 main bearing. It only shows up at low RPM- I was setting idle speed and found the noise around 600 RPM or so.

Any ideas? It sounds more and more like a "split the case" problem.




Link

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Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[wcfvw69]

Have you run it w/out the belt for the alternator?
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[esde]

I've heard this on an engine with a busted guide for the fuel pump pushrod. It was jammed in sideways and making a racket, but still operated the pump.
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modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that.

[jason]

Check easy stuff first. Fuel pump rod as mentioned, maybe distributor drive spring busted and its jumping around. Check valves and for exhaust leak.

[scrivyscriv]

Guys I'm ashamed to even admit what the problem was.

I have an A/C system in progress right now. The compressor pulley came loose on the engine pulley, so I removed it and tightened the engine pulley bolt back down minus the washer. I didn't even realize the washer is what secures the pulley down!

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Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[esde]

jeez, a human error?! I thought I was the only one that did that..
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modok wrote:
Bent cranks are silent but gather no moss. I mean, ah, something like that.

[mark tucker]

dam you got some real thin wall sockets to do that. and the marbles...were in you head, dont worry we all been there before on short trips and long ones too.Be gladd you made it all the way back.

[busdaddy]

Gotta love that, this went from "case split" to "missing washer", can't beat the simple fixes
And we've all done similar things, don't feel bad.
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[modok]

Darn, I was going to guess right for once.