Noticeable Brake Pedal Travel and Foot Pressure, 98 S70 T5

Ghassan · Post by **Ghassan** » 14 May 2007, 13:05

Good day everyone,

In the last 12 months or so, I have noticed that I have to apply noticeable foot pressure for moderate stopping power. The pedal travel is significant as well.

Upon my complaint, the service garage promptly performed a brake bleeding to remove the air. I was not convinced of this but I postulated this would be a good option. This improved the condition a bit but not to my satisfaction (it turned out I was right that brake bleeding was not the root cause of this condition). My brakes were near the end of their use and so the garage also did a brake job (pads, discs, etc..) a couple of week later. This also had a minor effect in terms of improvement and I was not convinced that the problem was resolved as the improvements were only marginal.

The garage guys drove the car upon my persistent complaint but they told me that the car's brakes are working normal. I believe they have adopted wide tolerance of what they consider normal range because they get cars in wide variety of conditons (no offense to them).

Is there a particular part that may have degraded (ex. seals in some component) that is causing a dissatisfying braking performance?

The best way to describe the condition is the deeper pedal travel and stronger foot pressure that is normally associated with near worn discs and pads that are near the end of their service use (ie larger gap development betw the pads and discs). However, this is not the case with my car as my pads and discs are only exhibiting about 30% use in the last 12 months and the problem is persistent.

Also note that I follow the owner's book religiously for inspections, services, and fluid flushes, etc...

thanks.
Ghassan S

1998 S70 T5 (1997 in-service date)
305,000km (~190,000miles)
Automatic

Post by **JRL** » 14 May 2007, 15:58

98's can have a strange master cylinder problem
Do the brakes work well (correctly) if you pump them once first?

Post by **redbrick** » 14 May 2007, 16:53

I bought my 99 V70 used, from a dealership. My test drives turned up what I thought was excessive brake pedal travel. They agreed to fix it as a condition of sale. They bled the brakes on it before I picked it up and called it fixed. It was better but not acceptable and gradually degraded to it's original condition. We went back and forth for weeks (because they would fix it and then the problem would slowly return). They replaced all four brakes, front calipers and bled the damned things three times. They were convinced that calipers would fix it. Apparently this is a more common problem. They did not. In the end a master cylinder was replaced. The car is now acceptable, the brakes are good, but I suspect that it is not as good as it was. I think you gradually get used to this problem if you have it. That's the only way I can rationalize how the previous owner of my car could have tolerated the brakes.
Good luck.

zenmervolt · Post by **zenmervolt** » 14 May 2007, 21:12

JRL wrote:98's can have a strange master cylinder problem
Do the brakes work well (correctly) if you pump them once first?

Mine does that. I've had the brakes checked and chalked it up to a quirk of the car. What is the root cause?

dasapir · Post by **dasapir** » 14 May 2007, 21:44

Ghassan when you mention fluid flushes, does that imply complete brake fluid flush? Water in the brake fluid (brake fluid is hydroscopic) can cause excessive pedal play.

Before jumping to change the master cylinder, if you have not done a complete brake line and reservoir brake fluid flush, you might do that. Bleeding the brakes alone would be insufficient. Though in the end the master cylinder may still be the problem.

zenmervolt · Post by **zenmervolt** » 14 May 2007, 22:24

dasapir wrote:Ghassan when you mention fluid flushes, does that imply complete brake fluid flush? Water in the brake fluid (brake fluid is hydroscopic) can cause excessive pedal play.

Before jumping to change the master cylinder, if you have not done a complete brake line and reservoir brake fluid flush, you might do that. Bleeding the brakes alone would be insufficient. Though in the end the master cylinder may still be the problem.

Sorry to hijack, but if a full flush has been performed with no change, how difficult is it to change the master cylinder?

dasapir · Post by **dasapir** » 15 May 2007, 18:32

Zenmervolt, I have not changed the brake master cylinder on a Volvo, however, if it is similar to other cars it should not be too difficult. Just slightly laborious and a little messy. A lot ot rags.

Aside from draining the fluid from the resevoir and disconnecting the lines the worst is again flushing all the lines. For me that means putting the car up on 4 stands so I can get to the bleeding nipples ( and I take the wheels of to allow even easier access). Also, if you do the master cylinder remember when re-attaching the brake pipe/lines not to tighten the fittings until you fill the resevoir and allow fluid to leak/seep out of the coupling before tightening.

good luck, hope that solves your mushy brake problem.

masstapro · Post by **masstapro** » 10 Jun 2007, 19:16

I too replaced all the brake pads and front rotors. Now I have no pressure.
Volvo mechanic replaced master cylinder and proffessionally bled the brakes.

Feels a little better but not even close to what it should be.

Pedal goes to floor but stops the car.
If I'm using the brakes every 10seconds, then they work good. After a few miles of not touching them, they lose pressure again.

ABS is working. The only thing we came up with is the ABS block under the master may have some air trapped.

They said when I pushed up the fluid from the calipers, I may have trapped some air or damaged something. It's best to open the bleaders first to not disrupt the fluid flow.

Please help!!!

~Shawn

cyclmck · Post by **cyclmck** » 10 Jun 2007, 20:05

If the effort seems increased it could be the booster leaking, you can use a vacuum pump on the inlet, pull a vacuum, see if it holds. The booster would not cause the pedal travel to increase though, so it sounds like master cylinder seals are leaking internally, with a light pressure on the brake pedal(like at a stoplight) does the pedal continue to go down further?

masstapro · Post by **masstapro** » 10 Jun 2007, 23:30

With pressure on the pedal it doesn't make it's way to the floor.

Master cylinder was replaced and cost me $200 for parts.
It basically didn't solve the problem. It just made it less frequent.

I still have to pump the pedal once to get it to act normally.

Maybe the break booster has a leak and needs a second pump to build enough pressure. Maybe there is a leak to or from the break booster.

I'm not sure how this all works, but I thought I'd search for the best answer before I take it back to my mechanic. This is a Volvo mechanic who specializes in older models, not a dealer.

~Shawn