Mechanical Inspection: Compression
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2003 Lexus SC 430, 2003 Lexus RX 300, 2003 Lexus LX 470, 2003 Lexus LS 430, and 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
Warm engine to normal operating temperature before checking compression. Ensure battery is fully charged. Remove ignition coils and spark plugs. On all vehicles except GX470, see IGNITION SYSTEM in REMOVAL & INSTALLATION - EXCEPT GX470 article. On GX470, see IGNITION SYSTEM in REMOVAL & INSTALLATION - GX470. Check engine mechanical condition with a compression gauge, vacuum gauge, or engine analyzer with throttle fully open. See engine analyzer manual for specific instructions. See COMPRESSION SPECIFICATIONS table. Install and tighten spark plugs to 13 ft. lbs. (18 N.m).
COMPRESSION SPECIFICATIONS
| Application | Specification | |
|---|---|---|
| Normal Compression Pressure | ||
| ES300 & RX300 | 218 psi (15.3 kg/cm2 ) | |
| GS300, IS300 & LX470 | 192 psi (13.5 kg/cm2 ) | |
| GS430, GX470, LS430 & SC430 | 178 psi (12.5 kg/cm2 ) | |
| Minimum Compression Pressure | ||
| ES300 & RX300 | 145 psi (10.2 kg/cm2 ) | |
| GS300 & IS300 | 156 psi (11.0 kg/cm2 ) | |
| GS430, GX470, LS430, LX470 & SC430 | 142 psi (10.0 kg/cm2 ) | |
| Maximum Variation Between Cylinders | ||
| Except ES300 & RX300 | 14 psi (1.0 kg/cm2 ) | |
| ES300 & RX300 | 15 psi (1.1 kg/cm2 ) | |