Freshly Rebuilt 1958 Olds 371 Knocking at Idle

Old December 26th, 2018, 04:01 PM
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1958 Olds Dynamic 88
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Freshly Rebuilt 1958 Olds 371 Knocking at Idle

Hello Everyone,I recently rebuilt my 1958 Olds 88 371. On initial startup engine sounded good but smoked a lot (Moly rings?). Rebuilt carb, replaced fuel pump, changed oil, changed plugs. my first fuel pump leaked fuel into oil pan but I did not drive more than 100 miles until I replaced pump and oil. Hoping it did not mess up my bearings .

Oil Pressure has always been 30-40PSIWas able to finally able to set rings for most part and does not smoke as much. Compression is all good in each cylinder. My engine now has a knocking/rattling sound at idle and appears to be getting worse the more I start it up and idle her. When I rev the engine it appears to go away or lessen.
I listened to engine block with stethoscope and did not hear any different or louder noises from cylinder to cylinder and noise appears to be coming from the lower rear engine/ front transmission area. One of my friend thinks its "thrust bearing". Another friend thinks it might be transmission related. I pulled the starter and flywheel cover to check to see if flywheel is loose or cracked but and all bolts are tight. I also verified very little flywheel play/movement (1/4"?). Before I drop oil pan to see if bearings are loose/damaged, could the knocking/rattling sound be something in transmission? Thanks Erol
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Old December 27th, 2018, 06:30 AM
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Old December 27th, 2018, 08:54 AM
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If a 58 is like a 55-56 it is a bitch to get the pan off and away from the engine enough to get to the rods and mains without loosing the transmission and motor mounts, pulling the distributor and a bunch of small stuff. Can you get us a youtube video of the sound you here. It's really hard to advise on a sound we can't hear. Have you herd wrist pin knock before? One other maybe..... Tedd
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Old December 28th, 2018, 09:55 AM
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Originally Posted by Rockabilly Hooligan View Post
I also verified very little flywheel play/movement (1/4"?).
If you mean front to back movement 1/4" is waaaaay too much. Crankshaft end play is usually in the neighborhood of .010" and hardly noticeable when prying the flywheel back and forth in the engine. If you really have 1/4" then that is more than likely your noise.
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Old December 29th, 2018, 01:13 PM
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Originally Posted by BillK View Post
If you mean front to back movement 1/4" is waaaaay too much. Crankshaft end play is usually in the neighborhood of .010" and hardly noticeable when prying the flywheel back and forth in the engine. If you really have 1/4" then that is more than likely your noise.
1/4 inch sounded like an awful lot of play to me, too?

Last edited by D. Yaros; December 29th, 2018 at 01:29 PM.
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Old December 29th, 2018, 02:28 PM
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