2002 V70 right rear brake not working

Muscleduck · Post by **Muscleduck** » 05 Mar 2019, 06:12

Hi all,

My first post here, and it's a question that's been frustrating me for weeks (months).
My rear right brake stopped working out of the blue. I went to MOT and my car was rejected because of a cracked windscreen. I replaced my windscreen and went back to MOT a couple of weeks later... and got rejected again, because my right rear brake completely stopped working.
I went to my local Volvo dealership and asked them to only check the problem, and call me first before repairing it. They told me they didn't exactly know what the problem was, but it was probably the ABS, and that it would cost me around 2k to figure out and repaair it. Since my car only cost me 3k, I told them to not fix my car.

My brother is an amateur/hobbyist mechanic and has checked my brakes but we can't seem to find the problem. Here's what we tried:
- Remove the caliper and clean and lube it
- Replaced the ABS module (the electronics)
- Some hard braking at speed, to the point of engaging the ABS
- Trying to bleed the brake line (dry as a bone)
- remove the caliper again, and try to feel a blockage with some iron wire. We got about 2 ft in the line before it got too hard to continue, but I'm not sure we were at the blockage yet. From what we could see it was just one of the bends in the line where we just couldn't continue. The wire was dry as a bone as well when it came out

So now we're kinda baffled because we have no idea what the problem is. I also have the ABS pump (purchased together with the electronics) but it would surprise me if that was the problem, since logic dictates (at least to me) that either none of the brakes would work, or all of them.

I also tried to find drawings of the brake system but couldn't find anything. Maybe one of you guys/gals know a website where I could find those? Maybe we're overlooking a part in the braking system.

The only other idea we have as of now is to use compressed air to try and blow out any blockage that might be present, though I'm just not handy enough to undertake disassembling my car, and my brother isn't too keen on trying every brake line to check which one is the faulty one (if that even is the problem).

If anyone has any other idea as to what could be wrong with my Volvo, I'd really appreciate any help.

Not sure if this matters, but it's a V70 P2 from 2002, 5 cyl gasoline, non-turbo with 140 hp.

Kind regards

Post by **abscate** » 05 Mar 2019, 06:52

Maybe we can figure out which line off the ABS pump is the rear line and apply compressed air to that line to see if its clear?

No brake fluid is definitely indicative of blockage somewhere - Does the P2 2002 have independent braking to the rear or is it just one fluid hard line to the rear wheels?

How about the soft lines to the rear caliper - that is definitely a place where they can swell and close off with age.

Muscleduck · Post by **Muscleduck** » 05 Mar 2019, 07:25

abscate wrote: ↑05 Mar 2019, 06:52 Maybe we can figure out which line off the ABS pump is the rear line and apply compressed air to that line to see if its clear?

No brake fluid is definitely indicative of blockage somewhere - Does the P2 2002 have independent braking to the rear or is it just one fluid hard line to the rear wheels?

How about the soft lines to the rear caliper - that is definitely a place where they can swell and close off with age.

That's what I'm hoping, though I don't know how to figure out which line on the ABS pump is the correct one. We only have a jack and some stands to lift up the car so we can get under the car, but we don't have a lot of space.

I would think the car has independent braking but I'm not sure. The ABS pump has 6 lines that enter/leave it. I don't think it's the soft line. When we used the wire to try and feel the blockage, we got way beyond that. However, now you mention soft lines I remember that from the caliper, there's first a soft line, then a copper one, and then again a soft one, that seems to just slide over the copper one. Maybe I'm mistaken though? It didn't seem like I would be able to take it off without breaking it (due to age). Thank you for your reply!

Muscleduck · Post by **Muscleduck** » 07 Mar 2019, 09:06

Anyone have any ideas/tips? Thanks.

Post by **chrism** » 07 Mar 2019, 10:36

Not sure if this diagram is 100% representative of your car or not, but it appears that both turbo and N/A are plumbed the same:

https://www.volvopartswebstore.com/show ... evel=24667

It show separate RH Rear and LH Rear lines, both originating at the ABS unit. Note there is some sort of disconnect mid way under the car that, if disconnected, may help you isolate the problem spot. Also, if you can get under there, you should be able to follow it all the way to the ABS and disconnect it there as was suggested.

Muscleduck · Post by **Muscleduck** » 07 Mar 2019, 12:20

Thank you for the drawing! Couldn't find it myself. Although it doesn't show me what like to look for at the ABS unit, at least now I know there's the disconnect which could hopefully be of use.

Post by **cn90** » 08 Mar 2019, 13:06

Just a theory...

The P.O. might have bled the brake using pressure (such as Motive device or air compressor etc.), allowing the reservoir to go empty and air entered the ABS Module.

Then he successfully bled 3 calipers but not the RR caliper.

I wonder if you can use VIDA software to "Cycle the ABS" during bleeding...

Just a thought...

Muscleduck · Post by **Muscleduck** » 10 Mar 2019, 05:45

My brother tried to bleed the RR caliper but everything was dry. He used some kind of device. I think it sucks the air out through the little valve? It looks like that motive device when I search for images. Would according to you air be trapped somewhere in the ABS module? And this causes the problem? The braking fluid level in the reservoir was OK according to the marks on the reservoir. In the middle between the min and max line. Though my brother thinks there could have been some moisture in the fluid because according to him the colour was a bit off. We have yet to replace it. I've cycled the ABS the 'manual' way by driving and then braking as hard as I can multiple times, but this didn't help.

Post by **abscate** » 10 Mar 2019, 05:58

If you can’t get brake fluid to the caliper with all of the other calipers closed something is wrong between the master cylinder and caliper. Find the right hoses by tracing and start disconnecting valve until you find the blockage. There isn’t going to be a pretty way to get this sorted out.

Post by **cn90** » 10 Mar 2019, 10:26

Below link is for a 2000 S40 but the culprit was a defective ABS Module:

https://volvoforums.com/forum/volvo-s40 ... eel-81742/