22 · Diagnostics

Brake pedal hard

Make: Alfa Romeo
Model: 147 Factory Service Manual
Year: 2000–2004
Section: Braking system › Brake pedal hard

‹ Prev Excessive brake pedal free play Next › Handbrake not efficient

Fault diagnosisBrake pedal hard

BRAKE PEDAL HARD

When the brake pedal is pressed, stiffness is felt during the pedal travel.

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Resting the foot on the brake pedal, check that the pedal sinks when the engine is started, because of the vacuum in the braking circuit	Continue to Step 1	Absence of or partial servo assistance	Continue to Step 1
1	CHECK ON VACUUM PIPE	All OK	Problems met	Operation
	Check vacuum pipe: must not be bent or damaged	Continue to Step 2	Pipe bent	Restore the correct geometry
	Check vacuum pipe: must not be bent or damaged	Continue to Step 2	Pipe damaged	Replace the damaged pipe Op. 3330D26
2	CHECK NON-RETURN VALVE	All OK	Problems met	Operation
	Check that the non-return valve is working properly	Continue to Step 3	Faulty operation	Replace check valve Op. 3330D26
3	CHECK BRAKE SERVO	All OK	Problems met	Operation
	Check in particular: that there are no air leaks that there is no seizing or sticking	Continue to Step 4	Brake servo with leaks	Replace the brake servo/pump assembly Op. 3330D02
		Continue to Step 4	Brake servo operation is jerky	Replace the brake servo/pump assembly Op. 3330D02
4	CHECK ON VACUUM	All OK	Problems met	Operation
	Check the vacuum level in the servo brake system Under particular conditions of use, low engine rpm with excessive use of the brakes, the vacuum for operating the servo brake may be insufficient resulting in hardening of the brake pedal. It is pointless replacing the servo unit.	Continue to Step 5	Value incorrect	Eliminate blockages in the manifold
		Continue to Step 5	Value correct	Replace the brake servo/pump assembly Op. 3330D02
5	CHECKING PUMP	All OK	Problems met	Operation
	Check that the brake pump has not seized Check that one or more wheels do not remain braked	Continue to Step 6	Seizure of the pump	Replace the brake servo/pump assembly Op. 3330D02
			Seizure of a front caliper	Replace the caliper Op. 3310A30
			Seizure of a rear caliper	Replace the caliper Op. 3310B36
			The car remains braked	Remove the servo/pump assembly Op. 3330D02and adjust the projection of the pushrod
			The car remains braked at the rear	Repair the handbrake
6	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Test the vehicle before delivery to the customer, to check that the fault is no longer present. The test is essential, as the braking system involves a safety feature of the car		Fault persists	Search for the fault starting from another symptom'

‹ Prev Excessive brake pedal free play Next › Handbrake not efficient

Parts & tools for this job For 2000 Alfa Romeo 147

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