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.

1993 BMW 535i AutomaticFACTORY OEM SERVICE PROCEDURE

Mechanical Inspection: Compression

Deactivate fuel injection system by removing Digital Motor Electronics (DME) master relay and fuel pump relay before performing compression test. See DME & FUEL PUMP RELAY LOCATION table.
Ensure battery is fully charged. Remove all spark plugs. Check compression with engine at normal operating temperature, air cleaner removed, throttle fully open and engine at cranking speed. See the ENGINE COMPRESSION SPECIFICATIONS table.

ENGINE COMPRESSION SPECIFICATIONS

Application

psi (kg/cm² )

Normal Compression Pressure ⁽¹⁾

142-156 (10-11)

⁽¹⁾	Maximum variation between cylinders and minimum compression pressure specifications are not available from manufacturer.

DME & FUEL PUMP RELAY LOCATION

Application

Location

535i

⁽¹⁾ Right Inner Fender Panel Of Engine Bay

⁽¹⁾	First relay (viewed from top to bottom) is Digital Motor Electronics (DME) master relay, followed by fuel pump relay and then oxygen sensor heater relay.

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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