V50 brake issues

[iain_o]

Normally I am a 245 owner but the wife wanted something more modern so we have got a V50 to go with the classic. It was super cheap because it has a few issues. I will be sorting the glow plug relay and additive tank in the next few weeks BUT the brakes are downright dangerous.

Earlier today I pulled the master cylinder (a pain compared to my 245) and all appears well, in fact it was replaced in 2010 so is quite alot newer than the car. The car has only done 30k miles since so I am not inclined to just throw another one on and hope for the best because some research has led me to THESE POSTS.

The problem could be described as
1. Driving down the road at any speed
2. Put foot on pedal
3. Brake works a little bit
4. The pedal keeps falling to the floor
5. 200ms later it stops working unless you push REALLY HARD but you still have very little braking

My guess is dodgy vacuum system which can't maintain the vacuum so the booster loses 'pull' and the pedal falls to the floor.

If anyone has had this problem and fixed it I would appreciate your input before I start buying replacement parts and hoping for the best.

My current plan is to reassemble and bleed the brakes tomorrow and then put some form of vacuum gauge on the feed to the booster so I can work out what is going on.

[iain_o]

So today has been interesting as there seem to be two possible avenues to investigate. Firstly the vacuum check valve seems a little dodgy (suck/blow test) so I need to phone Volvo and see if I can get another. It is dated 2005 so this is probably normal.

Secondly, the service history says that the brakes were bled and fine 6 weeks ago but clearly the bleed nipples are too rusty to have been undone in the last 12 months. It also has brand new pads which are not mentioned anywhere in its literature. My best guess is that it has not been serviced properly so who knows what condition the brake fluid will be in.

When I get more fluid I will be giving it a proper flush through to see what happens. Then I can investigate the vacuum system. I will keep you posted.

[StatusRed]

Was going to say when I was reading your first post it sounded like the vacuum when you say about the pedal keep falling.

A test I've heard for the vacuum is to have the car off and put your foot on the brake, turn it on and keep pressure on the brake and it should softly go down. I do this test every now and then to make sure the vacuum is working fine, especially after I recently changed all the calipers on my car.

[iain_o]

UPDATE: So as to not confuse those that search and find this in the future I FIXED IT.

After pulling the bleed nipples off the rust was not as thick as I first thought and the system had indeed had some work done to it. The problem was that Hendy, who had serviced the car all of its life, decided to put 10ml of water and grit in the brake system at some point, probably at its last 'service'. This obviously ripped apart the seal on the master cylinder and meant I couldn't get it out of the system. With a replacement master cylinder and a really good flush the water and grit appeared in the syringe I bleed into, the pedal came up firm and the vacuum valve seems fine as the booster is now not moving the master cylinder too far.

As suggested by Chris_C, always assume it is the hydraulics and sort them out first. One day I will learn

[KevMan2015]

Hi iain, pleased you sorted your car. Can I ask...where did you source your master cylinder from? I did it resemble the original? I have gotten a new mast cyl for mine, but it doesn’t look the same. I have searched the number off the original and got the oem number from Volvo, but when searched on google, all pictures show the ‘nee different’ style. Did you have to replace your brake lines from cylinder to abs valve? Thanks.

[Clan]

Originally Posted by KevMan2015

Hi iain, pleased you sorted your car. Can I ask...where did you source your master cylinder from? I did it resemble the original? I have gotten a new mast cyl for mine, but it doesn’t look the same. I have searched the number off the original and got the oem number from Volvo, but when searched on google, all pictures show the ‘nee different’ style. Did you have to replace your brake lines from cylinder to abs valve? Thanks.

The above post is 3 years old .

I have never heard of a Master cylinder fail on a S40/V50/C70/C30 since they were launched 16 years ago , that's seeing many of these cars daily on a professional basis .