Brake pressure

[lightyears]

Hi guys, I recently picked up a V70 TDI (D5252t)it runs quite well apart from the brakes, it feels like there is very little pressure in the pedal, although they do stop it’s not a snatchy as my old V70, I’ve read about and it may be the vacuum pump which looks like a huge pain in the bum to remove, is there any way it can be serviced/checked on the car?

[RollingThunder]

Its been a while since I had a diesel car, but IIRC, if the vacuum pump isn't working correctly the brake pedal gets very hard to push down? The vacuum pump gives the brake pedal assistance, so if the brake pedal can be depressed 'normally' then I'd assume it is ok.

It may simply be that you need to bleed the brakes (and ideally replace the brake fluid)

[Rich850R]

When was the fluid last changed and bled?!!

[lightyears]

Originally Posted by RollingThunder

Its been a while since I had a diesel car, but IIRC, if the vacuum pump isn't working correctly the brake pedal gets very hard to push down? The vacuum pump gives the brake pedal assistance, so if the brake pedal can be depressed 'normally' then I'd assume it is ok.

It may simply be that you need to bleed the brakes (and ideally replace the brake fluid)

The pedal depresses as normal, but when it gets to the bite it takes a lot of pressure for the brakes to catch. I think I will try the bleed and replace fluid first as I can see no record of it ever being done in 287K

Thank you both

[DaveNP]

Can we assume you've checked all of the basics like condition of the pads and discs, all of the calipers working fully and slide pins moving freely etc ? I've had a V70 can get an MOT with OK brakes but new pads made a massive difference.

[lightyears]

Originally Posted by DaveNP

Can we assume you've checked all of the basics like condition of the pads and discs, all of the calipers working fully and slide pins moving freely etc ? I've had a V70 can get an MOT with OK brakes but new pads made a massive difference.

You can assume correctly, had each wheel off this afternoon, other than being dirty they appear to be functional. However, the brake fluid is very very dark and kind of gloopy so I think I may have found the culprit, will bleed out the fluid and get some new stuff in.

[Martin Cox]

Sounds like a fluid change is long overdue. I'd suggest using a pressure bleeder rather than the traditional method of bleeding by pumping the brake pedal.

With the pressure bleeder there's no risk of taking the master cylinder seals beyond their normal travel and risking damaging them on anything nasty that may be lurking there.

With regard to the vacuum pump, yes it is awkward to get at one of the nuts holding it in place but not impossible. Some people use modified spanners or a piece of wire tied to a normal spanner.

The vacuum pumps rarely fail but they can get noisy with a distinctive clatter at idle.

Martin

1998 V70 Tdi Auto

[CNGBiFuel]

Originally Posted by lightyears

You can assume correctly, had each wheel off this afternoon, other than being dirty they appear to be functional. However, the brake fluid is very very dark and kind of gloopy so I think I may have found the culprit, will bleed out the fluid and get some new stuff in.

With fluid in such condition it'll be near neat acid. You say you've checked each corner? I'd suspect at least one caliper seized, and the ABS body won't take that treatment, iyou'd be very lucky if it's not trashed. If the fluid is actually black or near it, that's liquid rubber you're seeing. Dark green or blue, and it's nickel or copper. Beats me why people will focus on engine oil, and ignore brake-fluid. If the ABS body is trashed, after bleeding you'll still not 'get a pedal'. You'll get brakes OK, but at half-measure.

As the man says, this is a job for a pressure bleeder.