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08-18-2006, 12:19 PM
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#1 |
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Registered User
Join Date: Aug 2006
Location: Pittsburgh
Posts: 3
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Engine problem
I have a 1985 chevy C10 with a 1974 350 in it.
Coming home the other day it statrted making a loud rapping noise. I pulled the valve covers, checked all the rods and lifters. I pulled the oil pan, there are no metal shavings, the crank looks good as do the bearings. I also checked the fly wheel. I'm stuck here any help? The engine was just rebuilt both top and bottom end 900 miles ago. |
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08-18-2006, 01:22 PM
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#2 |
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Parts and more parts
Join Date: Nov 2003
Location: Lebo, Kansas (middle of nowhere
Posts: 6,821
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Re: Engine problem
Did you replace the fuel pump when you rebuilt it? If the fuel pump rocker arm starts to fail, it can sound like a really bad rod knock. I quess you need to clarify if the "Rapping" noise sounds as if it is from the top end or the bottom end. Maybe the camshft, lost a lobe.
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08-18-2006, 01:36 PM
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#3 |
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Registered User
Join Date: Aug 2006
Location: ocala fl
Posts: 19
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Re: Engine problem
go over it with a stethescope while it's running, you'll find it quick enough. post when you find it.
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08-18-2006, 01:38 PM
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#4 |
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Registered User
Join Date: Aug 2006
Location: ocala fl
Posts: 19
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Re: Engine problem
any loose sheetmetal on the engine that can be "flapping in the wind?" or does it do it at idle OR always?
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08-18-2006, 02:49 PM
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#5 |
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On a budget like Fred Sanford
Join Date: Oct 2005
Location: Topeka, KS
Posts: 2,031
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Re: Engine problem
I'd pull the intake and check the lifters for sure. Only way to know if you wiped a cam lobe or not. Just went through that myself.
__________________
'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread '98 Camaro z28: 370ci twin turbo 370ci build '01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD |
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08-19-2006, 12:56 PM
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#6 |
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Registered User
Join Date: Aug 2006
Location: Pittsburgh
Posts: 3
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Re: Engine problem
I checked the fule pump and it is ok. I'm going to pull the main bearings today. Can someone tell me the torque for them. It is a 1974 350. If that isn't the problem I'll check the lobe's and cam?
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08-20-2006, 12:09 PM
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#7 |
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Parts and more parts
Join Date: Nov 2003
Location: Lebo, Kansas (middle of nowhere
Posts: 6,821
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Re: Engine problem
Did you ever check to see if the noise is more predominant on the top end or down in the crankcase? Also a wrist pin a piston will cause a lot of noise, if it is going bad. This would be the time to just hang the motor on an engine stand and do a complete check from top to bottom. Better now, than on the road somewhere. You are already halfway there.
Last edited by piecesparts; 08-20-2006 at 12:09 PM. |
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08-21-2006, 02:36 AM
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#8 |
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Registered User
Join Date: May 2003
Location: Shreveport LA
Posts: 3,170
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Re: Engine problem
Sometimes a chunk of carbon will get between the top of the piston and the head and cause a knock that sounds kinda like a rod knock. Put it on fast idle, then slowly dribble some ATF down the carb throat until the engine dies. Wait an hour, then drive it kinda hard until the smoke goes away. That fixed mine a few times. Better to do this in an area where giant stinky smoke clouds are better appreciated, if possible.
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