Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

1990 Lexus LS 400FACTORY OEM SERVICE PROCEDURE

Engine Compression

COMPRESSION SPECIFICATIONS

Application		Specification
Compression Ratio
ES250		9.0:1
LS400		10.0:1
Compression Pressure		178 psi (12.5 kg/cm² )
Minimum Compression Pressure		142 psi (10 kg/cm² )
Maximum Variation Between Cylinders		14 psi (1.0 kg/cm² )

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.

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