engine started it ran very rough, missing badly?

2004 GMC C2500

135,000 MILES • V8 • 2WD • AUTOMATIC

RGPAOLINI

MEMBER
1 POST
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last night when engine started it ran very rough, missing badly. Turned it off and restarted after a minute, it stopped missing and ran pretty smoothly, when started this morning it was missing badly again and has a rather loud knock/ clacking sound from what appears to be the drivers side in the lower part of the engine. I changed plugs and wires but there is still a miss and knock.

Feb 2, 2010 at 4:09 PM

JACOBANDNICKOLAS

CAR REPAIR CONTRIBUTOR
110,190 POSTS

Hi,

An engine knock is usually an indication of a bad bearing. The crankshaft main bearings and the connecting rod bearings can both create this type of sound.

Take a look through this link first. It explains different engine noises, the probable cause, and what is required for repair.

https://www.2carpros.com/articles/engine-noises

At this point, you will likely need to remove the engine and oil pan to inspect the bearings. Start with the crankshaft and connecting rod bearing. If you look below, I attached the directions for how to perform the inspection.

I hope this helps. Let me know if you have other questions.

Take care,

Joe

See pics below.

Images (Click to enlarge)

Sep 5, 2021 at 9:35 PM

Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.