Brake peddle sinking into floor on 740 td

ladonamobile · Oct 25th, 2010, 21:33

The brake peddle on my new/old 740td estate stops the car but fades into the floor if I hold my foot down.

I am used to citroen bx rock hard foot-feedback.

Is this normal in volvo 740's?

If not how do I get it back to hard. It seems to pulse like an abs activation even though the car is standing still.

Oilydad · Oct 25th, 2010, 22:12

No....It's very definitely NOT normal, and you need to get it sorted. A car without brakes can be a very scary prospect!!

Braking systems on the 740 (like probably 90% of cars), are hydraulic. Put very simply, brake fluid is compressed when you press the brake pedal which in turn pushes the brake pads against the discs.

You've got a brake fluid leak somewhere on your braking system. Doesn't matter what car you drive, the pedal should NOT go to the floor when held.

Several possibilities: Leaking brake hoses, poor seals on caliper pistons, leaking master cylinder are probably the most common.

If there's no actual physical problem and you are lucky, then the brakes will simply need bleeding to remove air which is in the system. Air in the system will make the brake pedal feel spongy. Not good.

What you CAN do until you get it fixed, and to get an idea of what's wrong, is to make sure that you keep the brake fluid reservoir, under the bonnet, up to the maximum mark at all times, by topping it up with Brake Fluid. If it keeps going down, you've got a leak, but if not, you've got air in your system.

It's quite an easy job to bleed brakes, but unless you are SURE of what you are doing, let someone who does know help you with it.

Would you know how to do this, because if not, my advice would be to get a friend or garage to do it for you. If you think you could do it, then come back, and someone will help you with instructions, but as this is BRAKES it's important to get it 100% right.

Whatever you do, DO NOT IGNORE IT. It could cause you an accident if not dealt with.

vjck_uk · Oct 26th, 2010, 18:45

if there are no visible leaks and the master cylinder is still almost full then it could be your master cylinder has given up the ghost and will need replacing try standing on the brake as hard as you can see if it still goes down sometimes this will spread the cup seals if the fluid is passing them and will remain a hard pedal

Tomsk · Oct 26th, 2010, 18:51

Sounds like the master cylinder to me, but I'm no Volvo expert.

Oct 25th, 2010, 21:33	#1
ladonamobile New Member Last Online: Apr 19th, 2011 23:07 Join Date: Oct 2010 Location: Cleckheaton	Brake peddle sinking into floor on 740 td The brake peddle on my new/old 740td estate stops the car but fades into the floor if I hold my foot down. I am used to citroen bx rock hard foot-feedback. Is this normal in volvo 740's? If not how do I get it back to hard. It seems to pulse like an abs activation even though the car is standing still.

Oct 25th, 2010, 22:12	#2
Oilydad Premier Member Last Online: Mar 21st, 2016 21:21 Join Date: Aug 2009 Location: Exeter Devon	No....It's very definitely NOT normal, and you need to get it sorted. A car without brakes can be a very scary prospect!! Braking systems on the 740 (like probably 90% of cars), are hydraulic. Put very simply, brake fluid is compressed when you press the brake pedal which in turn pushes the brake pads against the discs. You've got a brake fluid leak somewhere on your braking system. Doesn't matter what car you drive, the pedal should NOT go to the floor when held. Several possibilities: Leaking brake hoses, poor seals on caliper pistons, leaking master cylinder are probably the most common. If there's no actual physical problem and you are lucky, then the brakes will simply need bleeding to remove air which is in the system. Air in the system will make the brake pedal feel spongy. Not good. What you CAN do until you get it fixed, and to get an idea of what's wrong, is to make sure that you keep the brake fluid reservoir, under the bonnet, up to the maximum mark at all times, by topping it up with Brake Fluid. If it keeps going down, you've got a leak, but if not, you've got air in your system. It's quite an easy job to bleed brakes, but unless you are SURE of what you are doing, let someone who does know help you with it. Would you know how to do this, because if not, my advice would be to get a friend or garage to do it for you. If you think you could do it, then come back, and someone will help you with instructions, but as this is BRAKES it's important to get it 100% right. Whatever you do, DO NOT IGNORE IT. It could cause you an accident if not dealt with. __________________ Are We Nearly There Yet! No longer a VOLVO owner, not by choice, but 'cause they don't make proper Volvos any more! Last edited by Oilydad; Oct 25th, 2010 at 22:25.

Oct 26th, 2010, 18:45	#3
vjck_uk Premier member Last Online: Jul 29th, 2017 15:54 Join Date: Nov 2002 Location: southern edge of birmingham	if there are no visible leaks and the master cylinder is still almost full then it could be your master cylinder has given up the ghost and will need replacing try standing on the brake as hard as you can see if it still goes down sometimes this will spread the cup seals if the fluid is passing them and will remain a hard pedal

Oct 26th, 2010, 18:51	#4
Tomsk New Member Last Online: May 22nd, 2014 19:28 Join Date: Jan 2009 Location: London	Sounds like the master cylinder to me, but I'm no Volvo expert.

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