Engine started it ran very rough, missing badly?

RGPAOLINI

MEMBER
2004 GMC C2500
V8
2WD
AUTOMATIC
135,000 MILES

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.

Tuesday, February 2nd, 2010 AT 4:09 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,176 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.

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