No compression in cylinder number three

2003 BUICK CENTURY
165,000 MILES • 3.1L • 6 CYL • 2WD • AUTOMATIC
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ALAZIM
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  • 2 POSTS
DTC PO303-Misfiring and running rough. I replaced coil pack, spark plugs and wires. I performed a compression test and discovered there was no compression in cylinder number three. No fluid on dipstick, however there is a ticking noise coming from inside the engine. What could be the real problem?
Nov 21, 2019 at 12:16 PM
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ASEMASTER6371
  • ✓ASE Certified Mechanic
  • 52,796 POSTS
  • ASE Certified Mechanic
Good afternoon,

You need to remove the valve cover and check and see if the rocker arms are moving for that cylinder.

https://www.2carpros.com/articles/the-reasons-for-low-compression

As far as possible issues,

1. Burned valve whether intake or exhaust valve.

2. Piston damage not allowing build-up of compression.

3. Broken valve spring on one of the valves.

Roy
Nov 21, 2019 at 12:45 PM
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ALAZIM
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Dear Roy. Sorry for the late reply. As you suggested; I pull the valve cover and discovered an unseated rocker arm (see photo). I decided to replace both heads and gaskets. Thanks
Image (Click to enlarge)
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Nov 25, 2019 at 6:06 AM
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ASEMASTER6371
  • ✓ASE Certified Mechanic
  • 52,796 POSTS
  • ASE Certified Mechanic
Good deal.

Roy
Nov 25, 2019 at 6:19 AM
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