Parts for your 1997 Mitsubishi Pajero-Brake booster

1997 Mitsubishi Pajero brake booster — what it does and how to look after it

Yes, the 1997 Mitsubishi Pajero is factory-fitted with a vacuum brake booster on both petrol (6G72/6G74) and diesel (4M40) models. This is documented in Mitsubishi Motors’ Workshop Manual (1997 Pajero/Montero, Group 35A “Power Brake — vacuum type”) and backed by the Mitsubishi ASA parts catalogue, which lists a power brake booster for 1997 Pajero variants (e.g., MR205318, MB857609, application varies by VIN/ABS). Mainstream repair manuals for the platform (Haynes and Ellery/Gregory’s) also cover booster testing and service, so the part is absolutely relevant for this model year.

The brake booster’s job is simple but vital: it uses engine vacuum to multiply pedal effort so the driver gets strong stopping power without standing on the pedal. On petrol Pajeros, vacuum comes from the intake manifold, on the 2.8 turbo-diesel, a dedicated vacuum pump feeds the booster. Inside the round booster housing is a diaphragm and a valve assembly that assists the master cylinder when the pedal’s pressed. It’s a big part of why the Pajero feels confident under brakes, especially when loaded or towing.

Signs a booster or its plumbing needs attention can include:

• A hard brake pedal and longer stopping distances
• A hissing noise near the brake pedal or booster
• Rough idle on petrol models when the brake is applied (vacuum leak)

A quick driveway check: with the engine off, pump the pedal a few times to deplete reserve vacuum, hold light pressure, then start the engine. If the booster’s working, the pedal should drop slightly as vacuum assistance kicks in.

As part of routine servicing, it’s smart to:

• Inspect the booster vacuum hose for cracks, soft spots, or oil saturation
• Test/replace the one-way check valve and grommet at the booster
• Make sure there’s no brake fluid weeping at the master cylinder-to-booster joint (a failing master can leak into the booster)
• Flush brake fluid on schedule to protect the hydraulics and ABS modulator

When replacement is needed, match the booster to the exact VIN and ABS setup, and don’t fiddle the pushrod length unless measuring to factory spec. Fit a new gasket, orient the check valve correctly, and reconnect the vacuum source (manifold on petrol, pump line on diesel). If the master cylinder is removed, bench-bleed it and then bleed the system per the Pajero procedure, particularly on ABS-equipped vehicles. After refit, do a careful road test in a safe area. If the pedal is rock-hard or braking performance is dodgy, park it up and get it rechecked—no dramas are worth compromised brakes.

FAQs

Does a 1997 Mitsubishi Pajero have a brake booster?
Yes. All 1997 Pajero variants use a vacuum-assisted brake booster, documented in Mitsubishi’s factory workshop literature and supported by parts catalogues for both petrol and diesel models.

What are the common symptoms of a failing Pajero brake booster?
Typical symptoms are a hard pedal, longer stopping distances, and a hissing sound at the pedal or booster. On petrol engines, a vacuum leak at the booster or hose can also cause a rough or high idle when the brakes are applied.

Can the Pajero be driven with a bad brake booster?
It may move, but braking effort skyrockets and stopping distance blows out. It’s not safe. If the pedal goes rock-hard or the car is slow to stop, arrange repair or towing rather than risking a drive.