Brake Pedal Going Stiff

petrohl34d · Jan 1st, 2019, 20:41

Sometimes my brake pedal goes stiff at the top of it's travel.

I still get good braking power, but the pedal is just very stiff and has barely any travel.

After I let off the pedal once, the feel of the pedal usually returns to normal.

Any ideas what's causing it?

volvo again · Jan 2nd, 2019, 10:30

Could be the pedal pivot bushes...
To replace means removing the pedal, I would try a squirt of silicon lubricant spray first, (or WD40 but this soon dries out)
If it's a manual is the clutch pedal the same? It has the same type of bushes

miccurr · Feb 5th, 2019, 20:40

Sticky Vacuum pump?

stuarts · Feb 6th, 2019, 10:28

Does it have a raspy feel to the pedal when this happens? If so, it may be a fault warning-abs sensor or similar. It is normally accompanied by a warning light but not always.

petrohl34d · Feb 6th, 2019, 19:25

Thanks guys.

Don't think it's bushings, and no doesn't feel raspy.

Basically just feels liek there's pressure build up in the system.

As I say, i still get a good brake, but the pedal is just stiff and doesn't travel very far.

When you say sticky vacuum pump, are you talking abuot valves, or that the piston is getting gunked up?

volvo again · Feb 6th, 2019, 19:27

Have you checked the servo?

petrohl34d · Feb 11th, 2019, 19:51

No, where is the servo and how do I check it? Thanks

volvo again · Feb 12th, 2019, 09:20

Big round thing on the bulkhead with the master cylinder attached ...

Turn off the engine
Press the brake pedal repeatedly until you feel a strong resistance ?(this means the vacuum still present in the system has been "used up")
Keep the brake pedal pressed down
Start the engine. If the brake pedal now yields, the servo is working properly

Possible there may also be a leak in the vacuum hose to the servo

miccurr · Feb 12th, 2019, 20:45

Had the same problem with my 98. Piston in the vacuum pump sticks. Usually when the car was started in the morning. Brake pedal would be practically solid but then return to normal. There is a fix somewhere on here. Basically, take it apart and clean it. Be warned however, the spring is a strong one and is difficult to compress for reassembly. I cross threaded the nut (didn’t know it at the time)and a few weeks later it blew apart. Luckily, no pieces went into the engine. Had to buy a new vacuum pump, but have had no issues since and that was about 100k ago. 236 k on it now and driving as new! Btw its not recommended to open the vacuum pump, replace if you can

Jan 1st, 2019, 20:41	#1
petrohl34d Senior Member Last Online: Jan 30th, 2023 20:21 Join Date: Jan 2016 Location: Enniskillen	Brake Pedal Going Stiff Sometimes my brake pedal goes stiff at the top of it's travel. I still get good braking power, but the pedal is just very stiff and has barely any travel. After I let off the pedal once, the feel of the pedal usually returns to normal. Any ideas what's causing it? __________________ 1998 Volvo V70 2.5 TDi - Dead @ 326,000 miles 1999 Volvo V70 2.5 TDi - Dead @ 250,000 miles 2005 Volvo XC70 2.4 D5 - Current daily

Jan 2nd, 2019, 10:30	#2
volvo again Master Member Last Online: Yesterday 12:04 Join Date: Jun 2018 Location: Presteigne, mid Wales	Could be the pedal pivot bushes... To replace means removing the pedal, I would try a squirt of silicon lubricant spray first, (or WD40 but this soon dries out) If it's a manual is the clutch pedal the same? It has the same type of bushes Last edited by volvo again; Jan 2nd, 2019 at 10:33.

Feb 6th, 2019, 19:25	#5
petrohl34d Senior Member Last Online: Jan 30th, 2023 20:21 Join Date: Jan 2016 Location: Enniskillen	Thanks guys. Don't think it's bushings, and no doesn't feel raspy. Basically just feels liek there's pressure build up in the system. As I say, i still get a good brake, but the pedal is just stiff and doesn't travel very far. When you say sticky vacuum pump, are you talking abuot valves, or that the piston is getting gunked up? __________________ 1998 Volvo V70 2.5 TDi - Dead @ 326,000 miles 1999 Volvo V70 2.5 TDi - Dead @ 250,000 miles 2005 Volvo XC70 2.4 D5 - Current daily

Feb 11th, 2019, 19:51	#7
petrohl34d Senior Member Last Online: Jan 30th, 2023 20:21 Join Date: Jan 2016 Location: Enniskillen	No, where is the servo and how do I check it? Thanks __________________ 1998 Volvo V70 2.5 TDi - Dead @ 326,000 miles 1999 Volvo V70 2.5 TDi - Dead @ 250,000 miles 2005 Volvo XC70 2.4 D5 - Current daily

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Feb 5th, 2019, 20:40	#3
miccurr Junior Member Last Online: Feb 22nd, 2024 19:27 Join Date: May 2010 Location: Strabane	Sticky Vacuum pump?

Feb 6th, 2019, 10:28	#4
stuarts Junior Member Last Online: Sep 8th, 2019 10:25 Join Date: Oct 2009 Location: Solihull	Does it have a raspy feel to the pedal when this happens? If so, it may be a fault warning-abs sensor or similar. It is normally accompanied by a warning light but not always.

Feb 6th, 2019, 19:27	#6
volvo again Master Member Last Online: Yesterday 12:04 Join Date: Jun 2018 Location: Presteigne, mid Wales	Have you checked the servo?

Feb 12th, 2019, 09:20	#8
volvo again Master Member Last Online: Yesterday 12:04 Join Date: Jun 2018 Location: Presteigne, mid Wales	Big round thing on the bulkhead with the master cylinder attached ... Turn off the engine Press the brake pedal repeatedly until you feel a strong resistance ?(this means the vacuum still present in the system has been "used up") Keep the brake pedal pressed down Start the engine. If the brake pedal now yields, the servo is working properly Possible there may also be a leak in the vacuum hose to the servo

Feb 12th, 2019, 20:45	#9
miccurr Junior Member Last Online: Feb 22nd, 2024 19:27 Join Date: May 2010 Location: Strabane	Had the same problem with my 98. Piston in the vacuum pump sticks. Usually when the car was started in the morning. Brake pedal would be practically solid but then return to normal. There is a fix somewhere on here. Basically, take it apart and clean it. Be warned however, the spring is a strong one and is difficult to compress for reassembly. I cross threaded the nut (didn’t know it at the time)and a few weeks later it blew apart. Luckily, no pieces went into the engine. Had to buy a new vacuum pump, but have had no issues since and that was about 100k ago. 236 k on it now and driving as new! Btw its not recommended to open the vacuum pump, replace if you can

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