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TurboDiesel2006 · Apr 9th, 2024, 11:21

Car is Volvo V70 D5 185 Euro IV with manual gearbox.

I am getting a very hard brake pedal after a two depressions. I push the pedal once - ok, then the second time the pedal gets hard at the end of the travel and if I try a third time it is very hard and retardation is poor. If I release the brakes then a couple of seconds later it is ok but goes into the same cycle.

From other threads and internet search the symptoms are indicative of a lack of servo boost.

My car has the mechanical camshaft driven brake vacuum pump on the LHS of the engine. Whilst replacing the swirl flaps I noted this was leaking oil, so took it off and replaced the seals. All seemed ok.

I had not used the car between replacing the vacuum pump seals and experiencing this problem (see rear brakes comment below) so my immediate suspect was the pump.
I have checked the vacuum from the brake vacuum pump and am getting;
Servo Outlet - 29psi (59 inhg, 199pka), steady reading at engine idle
Engine Mount Outlet - 10psi (20.3 inhg, 68 kpa), steady reading at engine idle.
I have no idea if these figures are good or bad. Can anybody advise please before I buy a new vacuum pump?

I have just finished replacing the rear discs, pads, handbrake pads, levers and cables and used new slider pins well lubed so I don't think it is this causing the hard brake pedal. I bled the entire system at the same time and have no sticking pads. The front calipers were renewed in 2020.

Any ideas please.

Apr 9th, 2024, 11:21	#1
TurboDiesel2006 V70 D5 185 Owner Last Online: May 23rd, 2024 17:41 Join Date: Nov 2014 Location: Ipswich	Hard brake pedal V70 D5 Euro4 Manual Car is Volvo V70 D5 185 Euro IV with manual gearbox. I am getting a very hard brake pedal after a two depressions. I push the pedal once - ok, then the second time the pedal gets hard at the end of the travel and if I try a third time it is very hard and retardation is poor. If I release the brakes then a couple of seconds later it is ok but goes into the same cycle. From other threads and internet search the symptoms are indicative of a lack of servo boost. My car has the mechanical camshaft driven brake vacuum pump on the LHS of the engine. Whilst replacing the swirl flaps I noted this was leaking oil, so took it off and replaced the seals. All seemed ok. I had not used the car between replacing the vacuum pump seals and experiencing this problem (see rear brakes comment below) so my immediate suspect was the pump. I have checked the vacuum from the brake vacuum pump and am getting; Servo Outlet - 29psi (59 inhg, 199pka), steady reading at engine idle Engine Mount Outlet - 10psi (20.3 inhg, 68 kpa), steady reading at engine idle. I have no idea if these figures are good or bad. Can anybody advise please before I buy a new vacuum pump? I have just finished replacing the rear discs, pads, handbrake pads, levers and cables and used new slider pins well lubed so I don't think it is this causing the hard brake pedal. I bled the entire system at the same time and have no sticking pads. The front calipers were renewed in 2020. Any ideas please.