Performed 100 hour inspection on engine. Compression check: #1-68/80, #2-70/80, #3-15/80, #4-70/80. Replaced Cyl #3 with overhauled cylinder, piston and new rings. Post repair compression is 74/80 for #3. Drained oil and refilled with 7 quarts Aeroshell W100 plus oil. R&R oil filter with new CH48111-1. Cut and inspected old filter, no metal found. Replaced intake gaskets P/N-71973. Replaced all 4 exhaust gaskets P/N-77611. Replaced bottom right engine mount with new P/N-j-9613-40. Removed, cleaned, inspected, gaped, tested, and rotated spark plugs. Work done in reference to Cessna 172 MM, IPC, and FAR 43 app d. I certify that this engine was inspected in reference to Cessna 172 100 hour inspection checklist and was found to be in an airworthy condition and is approved for return to service at this time.