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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: lukieg on January 21, 2012, 09:05:13 am
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Since putting in my tall deck.. it has always had a slight tapping.. only when idiling at low rpm.. it goes away as soon as the rpm imcrease above roughly 1000.. It goes away under load, its recently gotten worse.. it sounds like a lifter.. but super loud.. i have put 8000 km on it since install and it still runs good.. ihave noticed lately the idlehas become a bit rough... seems to chug to the ticking noise if that makes any sence... i cant tune the idle smooth as i could before??? The mileage is unknown.. oil comes out super clean.. no smoke on startup runs fine and sounds and works great... aside from this noise.. Please help me..
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Just a clarification question so we can help. Would you say the noise is more mechanical ( like a lifter ) or more like a pinging compression issue ?
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pinging at idle?
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no shes defiantly mechanical
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Try going through and adjusting your lifters. I had a 327 in a 63 C10 that I swore was a rod knock. It ended up being a lifter out of adjustment. My 327 had sat for several years before putting it in the truck.
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thanks for the quick replys.. i have adjusted them to death... it still doesnt seem to help,
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Have you had the pan off?
Could be a broken piston skirt or two / three.
We had a C60 with a 427 a few years back that we serviced, inspected, etc. for a guy. For several years it always had a tapping noise at idle but would go away when reved or under a load. Seemed to get a little quieter when up to temp too. After a while the oil pan rotted out. We took it off to install a new one, and found three piston skirts in the pan. He is still running it but that's what we think the noise is.
Years ago when I worked at the local oil / propane company we had an F350 2 wheel drive pick up truck with 351 HO Windsor. It sounded like the thing was gonna blow lunch every time you started it at an idle. Rev it up the noise would go away. Once it was warm it was almost non existent. The drain plug eventually stripped out on that pan. When we changed that we found 7 piston skirts in that one!
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Here are three more ideas:
1) Pull your spark plugs for inspection (keep them in order) and tell us how they look, especially whether there's any mechanical damage.
2) What's your oil pressure at idle and above 1000 RPM?
3) Does the noise change with engine temp?
...Could be a broken piston skirt or two / three. ...we found 7 piston skirts in that one!
Blazin, that's wild. Did you ever determine the cause?
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the plugs look good... the noise gets worse as it warms and oil pressure is constant and good.
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the plugs look good... the noise gets worse as it warms and oil pressure is constant and good.
Now that does sound like it is mechanical. I am very interested in learning what it is when you finally figure it out, keep up posted and good luck.