Cooling System

With engine off, wipe radiator filler neck seat clean. Fill radiator to correct level. Attach tester to radiator and pump tester until pressure is at upper level of radiator pressure cap rating. See COOLING SYSTEM SPECIFICATIONS table.
If pressure drops, inspect for external leaks. If no leaks are apparent, detach tester and run engine until normal operating temperature is reached. Reattach tester and observe. If pressure builds up immediately, a possible leak exists from a faulty head gasket, crack in cylinder head or engine block.
CAUTION: Pressure may build up quickly. Release any excess pressure or cooling system damage may result.

If there is no immediate pressure build up, pump tester to within system pressure cap range. Vibration of gauge pointer indicates compression or combustion leak into cooling system. Isolate leak by shorting each spark plug wire. Gauge pointer should stop or decrease vibration when leaking cylinder is shorted.

COOLING SYSTEM SPECIFICATIONS

Application

Thermo. Temp. °F (°C)

Rad. Cap psi

Coolant Capacity Qts. (L)

2.5L

195 (91)

12-15

⁽¹⁾ 10 (9.5)

4.0L

195 (91)

12-15

12 (11.4)

4.2L

195 (91)

12-15

10.5 (9.9)

5.9L

195 (91)

12-15

15.5 (14.7)

⁽¹⁾	Wrangler 9 qts. (8.5L).