2000 V70R - AWD Brake system questions?

[scot850]

Couple of questions that have come up in the days approaching (the hopeful) return of the braking system following the rear end re-build.

As it has been many year since I have had to bleed a brake system, I happened to ask a Volvo mechanic I know if there was an order in which to bleed the brakes. He says he always does, RH rear, LH rear, RH front and LH front (closest to the master cylinder). This jarred in my mind, so I looked up on Vida and it says to do this in the total reverse to this advice. It says start on LH front and go in the reverse to the RH rear last. This aligns with what I was always told since starting working on cars. The quest ion here is then, does it really matter? On the P80 AWD the rear brakes are on separate lines for sure, and I am fairly certain the fronts are also. So really is it a moot point?

Second issue, was I noticed on Vida that when setting up the parking brake, Vida says to tighten the parking brakes at the rear drum/rotor until no movement, and then back off SIX (6) clicks. I have always used 3-4. This issue comes up regularly with the parking brakes, so thoughts? Again I know what works for me, so will run the course on both issues, but willing to hear other opinions?

Neil.

[Blockpartie]

Couple of details that are important to know:

1) What kind of brake line setup you have depends on the model year! 1997 and 1998 P80 AWD have only one rear brake line. It splits into two hardlines at the jacking point which makes bleeding it not so much fun.

2) Your mechanic might always start with the RH line as it is the longest one and can trap the most air, requiring you to add loads of fluid. You can do whatever you want in regards to bleeding the lines but generally it's advisable to follow the usual order of shortest lines first so the master cylinder doesn't suffer from some air bubble that might be trapped in that area.

Parking brake setup depends on your preferences. There is no pro or con for any of the two ways as wear on the parking brake shoes (and necessary readjustment) depends highly on how much you use it.

[jimmy57]

The order makes ZERO difference unless the system is dry. The order business has always been about getting the most air out the fastest to reduce fluid waste while bleeding. For brake fluid change the time and fluid it takes to get the old pushed out is ONLY a factor of how long the lines are. A 2000 has 4 channel system with each brake line running independent (no T fittings) from ABS pump/module to the calipers. The 98 and older always use a T at rear and the older without ABS and using dual diagonal split have the most line length.

The order if dry is only important if foot pump bleeding. If using pressure bleeding then it is still unimportant.

There can be an order difference on some vehicles (not Volvos to date) where the ABS system is commanded with a scan tool to use the pump and circuit solenoids to bleed system.

[scot850]

Thanks to Blockpartie and jimmy57. Both of your inputs are extremely helpful. Looks like it will be Monday now before I will get to the system to possibly bleed it. Had to re-paint the rear hubs again due to me damaging them during install. Also forgot I hadn't removed the old seal between the hub and the dust shield, and then had to de-rust and re-paint prior to fitting the new seal. This stuff always takes longer than you think.

Here is a question for you all. Why when the handbook for our cars says to use DOT4+ brake fluid, why is the fluid Volvo supplies stamped DOT4 only?

Neil.

[Big Will]

That's weird. I remember the little 1/2 liter bottles of Volvo brake fluid being DOT4+...maybe they changed it recently? I use ATE Type 200 brake fluid. Used to use the Super Blue stuff and alternate as it was easy to see the color change when refreshing the fluids. Of course the Super Blue stuff isn't legal anymore in the U.S. so that's all gone from the market.

[scot850]

Thanks Will. I did read about the ATE Super Blue being outlawed in NA. I know the main difference between the DOT4 and DOT4+ is the boiling point changes from something like 165 to 180 degrees. But also have read that in colder temperatures you may need a different fluid. Still doesn't make sense when the handbook says DOT4+. I don't drive like a crazy so boiling the fluid shouldn't be an issue. Also don't tend to drive too far either as my wife doesn't use a car for work and I am retired. The 'R' has only completed about 6000km in 3 years and that includes when I was working!

Neil.

[jcdillin]

If you don't have a pressure bleeder i'd get one, or build one. I just did all the brakes on my AWD and changed the fluid and couldn't get it bled right by pedal. Built the power bleeder and it went really fast and easy.

https://www.matthewsvolvosite.com/forums ... hp?t=29243

[scot850]

Thanks for the advice JC. I've heard of this issue before, but had forgotten about it. I think I may have a pressure bleeder somewhere, otherwise will look at your design for the home built version.

Neil.

[scot850]

Finally got the brake system re-built. Hard pipes were a pain as on all AWD P80's.

Got my son to help as the peddle pusher and worked my way around the car starting at LF corner (nearest the master cylinder). No air came out after several pumps, so went to RF corner. Again little air came out. LR corner at least some air came out but not much. Finally RR. With new pipe from the LH side expected a lot of air but not as much as I expected. Typically, brake peddle was rubbish and soft.

Round the houses again, and this time air at all 4 corners, especially the rear. Peddle was better but still soft. Went around again, and this time a crap load of air came out at the rear calipers and bingo, the hard brake peddle! Not convinced all the air is out, but peddle feels good for now.

Thanks for the advice and guidance.

Neil.