RAM 3500 Truck 2WD V8-5.7L VIN D (2003)
Radiator Cap: Component Tests and General Diagnostics
Cooling System Pressure Relief Testing
DIAGNOSIS AND TESTING - RADIATOR CAP-TO-FILLER NECK SEAL
The pressure cap upper gasket (seal) pressure relief can be tested by removing overflow hose from the radiator filler neck tube. Attach the hose of the
pressure tester tool 7700 (or equivalent) to the tube. It will be necessary to disconnect hose from its adapter for the filler neck. Pump air into radiator.
The pressure cap upper gasket should relieve at 69 - 124 kPa (10 - 18 psi) and hold pressure at a minimum of 55 kPa (8 psi).
WARNING: THE WARNING WORDS "DO NOT OPEN - HOT" ON RADIATOR PRESSURE CAP, ARE A SAFETY PRECAUTION.
WHEN HOT, PRESSURE BUILDS UP IN COOLING SYSTEM. TO PREVENT SCALDING OR INJURY, RADIATOR CAP SHOULD
NOT BE REMOVED WHILE SYSTEM IS HOT AND/OR UNDER PRESSURE.
Do not remove the radiator cap at any time except for the following purposes:
1. Check and adjust antifreeze freeze point.
2. Refill the system with new antifreeze.
3. Conducting service procedures.
4. Checking for vacuum leaks.
WARNING: IF VEHICLE HAS BEEN RUN RECENTLY, WAIT AT LEAST 15 MINUTES BEFORE REMOVING RADIATOR CAP.
WITH A RAG, SQUEEZE RADIATOR UPPER HOSE TO CHECK IF SYSTEM IS UNDER PRESSURE. PLACE A RAG OVER CAP
AND WITHOUT PUSHING CAP DOWN, ROTATE IT COUNTERCLOCKWISE TO FIRST STOP. ALLOW FLUID TO ESCAPE
THROUGH THE COOLANT RESERVE/OVERFLOW HOSE INTO RESERVE/OVERFLOW TANK. SQUEEZE RADIATOR UPPER
HOSE TO DETERMINE WHEN PRESSURE HAS BEEN RELEASED. WHEN COOLANT AND STEAM STOP BEING PUSHED INTO
TANK AND SYSTEM PRESSURE DROPS, REMOVE RADIATOR CAP COMPLETELY.
Radiator Cap Testing
DIAGNOSIS AND TESTING - RADIATOR CAP
Remove the cap from the radiator. Be sure that the sealing surfaces are clean. Moisten the rubber gasket with water and install the cap on the pressure
tester 7700 or an equivalent.
Operate the tester pump to bring the pressure to 104 kPa (15 psi) on the gauge. If the pressure cap fails to hold pressure of at least 97 kPa (14 psi)
replace the cap. Refer to the following CAUTION.
The pressure cap may test properly while positioned on tool 7700 (or equivalent). It may not hold pressure or vacuum when installed on the radiator.
If so, inspect the radiator filler neck and radiator cap's top gasket for damage. Also inspect for dirt or distortion that may prevent the cap from sealing
properly.
CAUTION: Radiator pressure testing tools are very sensitive to small air leaks which will not cause cooling system problems. A pressure cap that
does not have a history of coolant loss should not be replaced just because it leaks slowly when tested with this tool. Add water to tool. Turn tool
