AN SMA PLT MADE A PRECAUTIONARY LNDG.

Narrative

FLYING A CESSNA 172/0; I HAD TO DIVERT FROM MY HAYWARD OBJECTIVE. THE ACFT EXPERIENCED AN ENG ROUGHNESS SEVERE ENOUGH TO SHAKE THE AIRPLANE. AN OAKLAND PLT ALSO A FLT INSTRUCTOR; EXPERIENCES THE SAME CONDITION. I ALSO DIVERTED S FROM THE LINDEN RADIAL 229 TO ALSO COMPLY WITH VFR FOR CLOUD CLRNC ALONG WITH THE ENG SYMPTOMS. NOT EXPECTING TO PUT DOWN IN LIVERMORE; I DID NOT HAVE THE CTAF DIALED INTO THE RADIO. REALIZING THE ARPT WAS THERE AND I WAS XING OVER FROM N TO S; I ENTERED L TFC PATTERN FOR RWY 25R IN ACCORDANCE WITH CLASS 'G' PROCS. SINCE ALL OF THIS HAPPENED QUICKLY AND INTENSELY IN A CLOSE TFC ENVIRONMENT AND POOR COCKPIT LIGHTING EVEN WITH A FLASHLIGHT HANDY; I WAS NOT ABLE TO LOOK UP THE FREQ AND OBSERVE OUTSIDE ARPT TFC CONDITIONS. I WAS ALREADY DOWNWIND TURNING BASE. WHEN BANKING TO TURN BASE; I NOTICED AN AIRPLANE THAT APPEARED TO BE BELOW ON STRAIGHT APCH TO RWY 25R. I INSTEAD PROCEEDED ACROSS RWY 25R ACROSS HIS APCH PATH AND; OBSERVING NO OTHER TFC IN THE AIR OR ON THE GND. PROCEEDED TO LAND ON THE N ADJACENT TXWY LEAVING RWY 25R OPEN FOR THE APCHING ACFT. THE TWR APPEARED NOT TO BE IN OP. I DO NOT BELIEVE I CAUSED A TFC CONFLICT OR REQUIRED A DIVERSIONARY PROC BY THE OTHER AIRPLANE. I PAUSED AT THE BASE OF THE TWR IN CASE ANYONE WANTED TO QUESTION ME; NOTHING HAPPENED. I PROCEEDED TO RWY 25R; DIALED IN THE CTAF. THE OTHER AIRPLANE THAT LANDED WAS NOT AROUND. I ANNOUNCED RWY 25R L XWIND DEP AND LEFT. I COULD NOT GET TO HAYWARD; SO I RETURNED TO LIVERMORE; ANNOUNCED AND ENTERED L TFC RWY 25R BY CLASS 'G' COM PROCS AND LANDED. AS I TAXIED TO TRANSIENT PARKING; ANOTHER AIRPLANE WITH OTHER ACFT EVEN THOUGH ON THE CTAF. ABOUT 3 MONTHS AGO; AN INSTRUCTOR LNDG AT NIGHT AT HAYWARD; TAXIED THIS AIRPLANE INTO A DITCH. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATES THAT THE PROB WITH THE ENG WAS A BROKEN ENG MOUNT. THE ENTIRE ACFT WOULD OCCASIONALLY VIBRATE. THE ENG CHKED OUT FINE ON THE GND AT LVK; SO THE RPTR PRESSED ON TO HWD ONLY TO FIND THE WX BELOW HIS; OR THE ACFT'S CAPABILITIES. THE ACFT WAS RETRIEVED THE NEXT DAY. THERE HAVE BEEN NO REPERCUSSIONS FOR ANY OF THE FACETS OF THIS INCIDENT. THE RPTR THOUGHT THAT THE ENG PROB WAS CARBURETOR ICE AS LOW CLOUDS WERE ROLLING OVER THE HILLS FROM THE W.