2000 Dodge Caravan Compression test

MR. TIMING BELT CONTROLS THE CAM. THE CAM "OPENS AND CLOSES" THE VALVES

BOTH THE INTAKE, AND EXHAUST VALVES MUST BE IN THE CLOSED POSITION IN ORDER TO "BUILD COMPRESSION". OTHERWISE, THE AIR IN THE EACH CYLINDER WOULD BE PUSHED OUT OF AN OPEN VALVE

TO MAKE THIS "FAIR"

IF YOU MANUALLY ROTATE THE CAM(S) UNTIL YOU CLOSE OFF EACH CYLINDER VALVES. CRANKING THE ENGINE OVER WILL BUILD PRESSURE IN THAT PARTICULAR CYLINDER. THEN YOU WOULD HAVE TO REPEAT THE PROCESS UNTIL YOU DID ALL OF THE CYLINDERS

. NOW HERE'S THE BIGGIE!

I DON'T KNOW WHAT ENGINE YOU HAVE OR IF IT "COULD BE" AN "INTERFERENCE ENGINE". OR NOT

. INTERFERENCE. MEANING, IF THE TIMING BELT IS NOT "ON" AND KEEPING THE VALVES "TIMED" WITH THE PISTON TRAVEL (POSITION). THE VALVES MIGHT HIT THE PISTONS
(MAYBE A BETTER EXPLANATION MIGHT BE, THE VALVES AND THE PISTONS "SHARE" THE SAME PLACE. JUST AT DIFFERENT TIMES)

*********DOING THE "MANUAL" CAM TURNING WOULD NOT BE A "GOOD IDEA" ! ! ! ! !********

(AS SOMEWHERE IN THE ENGINE, A VALVE WOULD BE IN THE "DOWN" POSITION AND THE PISTON MIGHT HIT IT ON THE WAY UP)

ON THE OTHER HAND

IF YOUR ENGINE IS A "NON-INTERFERENCE ENGINE". IT WOULD BE IMPOSSIBLE FOR THE VALVES TO HIT THE PISTONS. IF THE TIMING BELT BROKE WHILE THE ENGINE WAS RUNNING. NORMALLY, THIS IS BECAUSE THE VALVES ARE "ENGINEERED" TOO FAR AWAY FROM THE PISTONS, TO EVER HIT THEM

THE MEDIC

YOU SORTA LOST ME ON THAT QUESTION

THE WAY YOU PERFORM A COMPRESSION TEST IS TO REMOVE THE SPARK PLUGS (SOME DO THIS ONE AT A TIME. OTHERS SNATCH 'EM ALL OUT)

THEN YOU MAY HAVE 2 OPTIONS TO "SEAL" THE COMPRESSION GAUGE TO THE SPARK PLUG HOLE

A) AN ADAPTER SCREWS INTO THE SPARK PLUG HOLE. AND IS "PIPED" INTO THE GAUGE, IT TAKES TIME TO SET THIS UP. HOWEVER, YOU DON'T HAVE TO "PUSH HARD" AS WITH (B), THIS METHOD IS USED IN HARD TO GET TO PLACES FOR THE GAUGE

B) MOST OF THE TIME THE COMPRESSION GAUGE HAS A RUBBER POINTED TIP THAT YOU SHOVE INTO (AND AGAINST) THE SPARK PLUG HOLE. YOU MUST HOLD IT IN THERE TIGHT USING HAND PRESSURE

IF YOU HAVE LEAKS BETWEEN THE ENGINE AND GAUGE (IT WON'T BE ACCURATE) MOST LIKELY YOU WILL HEAR IT HISS

IN BOTH CASES, NORMALLY YOU CRANK THE ENGINE WITH THE STARTER.3.4.5.6 OR SO REVOLUTIONS

THE PRESSURE IN THE CYLINDER IS TRANSFERRED TO THE GAUGE. MOST GAUGES WILL "HOLD" THE READING UNTIL YOU MANUALLY PUSH A BUTTON ON THE GAUGE TO RELEASE THE PRESSURE TO RE-ZERO THE GAUGE

THESE ARE MY DINOSAUR GAUGES. VACUUM IN THE MIDDLE. COMPRESSION ON THE RIGHT

IF I UNDERSTAND YOU RIGHT. YOU CANNOT PERFORM THIS TEST, UNLESS YOU CAN MAKE THE PISTON COMPRESS AIR ON THE "COMPRESSION STROKE". ENGINE MUST TURN OVER

THE MEDIC