Mitsubishi S4S-D — Testing Compression Pressure
Testing & diagnosis · Engine cylinders
For the Mitsubishi S4S-D, from the Mitsubishi service manual.
Applies to: Mitsubishi S4S-D, Mitsubishi S4S engine
Before you start
- Measure all cylinders; do not assume condition from one cylinder.
Procedure
- Move control lever to STOP position.
- Remove glow plugs from all cylinders.
- Install gage adapter and compression gage on cylinder being measured.
- Crank engine with starter and read gage at which needle stabilizes.
- If measured value is at or below limit, overhaul the engine.
- Measure all cylinders.
Tools required
- Compression gage 33391-02100 Amazon
- Gage adapter 30691-21100 (swirl chamber) Amazon
- Gage adapter 32491-04100 (direct injection) Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Swirl chamber: standard 3.23 MPa (33 kgf/cm2) [469 psi], limit 2.84 MPa (29 kgf/cm2) [413 psi]
- Direct injection: standard 2.94 MPa (30 kgf/cm2) [427 psi], limit 2.64 MPa (27 kgf/cm2) [384 psi]
- Engine speed 300 min-1
Source: Mitsubishi service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.