There are four methods of bleeding brakes - gravity bleeding, manual bleeding, vacuum bleeding, and pressure bleeding. All of the methods are designed to remove air bubbles from the system and/or flush the braking system with fresh fluid after caliper servicing or brake line replacement. However, some work better than others.

• Gravity Bleeding is the slowest method to bleed the brakes, and the least likely to work on modern vehicles. With gravity bleeding you remove the reservoir lid and keep it full with the brake bleeders open at the same time. Assuming the receiver is the highest point in the system, and that there are no leaks or loops in the system I have seen it work on some older cars (non-ABS).
• Manual Bleeding involves opening the bleeder valve while a second person pushes the brake pedal down, forcing brake fluid out the bleeder. The bleeder valve is then closed, and the second person lifts the brake pedal up. This process is repeated until the fluid has been flushed and and all of the air has been purged from the system. It is a very simple method, however may not be 100% effective on more complicated systems like modern four-wheel ABS disc brakes.
• Vacuum Bleeding is performed by using a handheld vacuum pump (MityVac is a common unit) to apply a vacuum (equivalent to about 10psi) on each brake caliper, and using it to "draw" the old fluid and/or air out of the system. The nice thing about the MityVac hand pump is that it can be used to perform other automotive diagnostic tests on diaphragms, sensors, actuators, etc so even if it does not work for brake bleeding on a particular vehicle, it has other uses.
• Pressure Bleeding uses a pressurized tank filled with brake fluid and an adapter that replaces the master cylinder reservoir cap. The tank is pressurized to about 20psi and brake fluid is then forced through the entire braking system. Pressure bleeding is the best method to bleed just about any brake system, including ABS systems (which usually require pressurized bleeding).

For a long time I used the manual method. The problem is if you didn't get the rhythm down just right with your helper air ends up in the system and you would have to start over again. To alleviate this I started using Speed Bleeders, which are replacement bleeder screws with a check valve inside that only allow brake fluid to flow one direction. They run about $30 for a set of 4 and work fairly well, but you have to keep a close eye on the brake fluid reservoir because if it empties air will get in the system and you have to start over again. I ordered some Speed Bleeders for the 850 but when I installed them I discovered that they have the correct thread pitch but their overall length is too long, causing them to bottom out in the caliper and leak when tightened fully.

I put the stock bleeder screws back in and tried to vacuum bleed the brakes using a MityVac handheld brake bleeder. Even though many people swear by this method I was not able to get it to work probably because it appeared the MityVac was not able to draw a powerful enough vacuum on the system to work.

I did a little searching and came across the Motive Power Bleeder. You can get them directly from Motive Products and they run about $50 for the European Bleeder (part 0100). While that sounds like a lot, it is only slightly more expensive than a set of Speed Bleeders, and the first time you use the Power Bleeder you will realize that it's worth every penny. When you are using performance brake fluid (Motul 600, ATE Gold/Blue, etc) there's nothing more upsetting them seeing your $15/bottle fluid end up on the floor due to overbleeding or having to rebleed all over again because you were not able to expel all of the air.

The Power Bleeder can't be any easier to use. Simply fill the Power Bleeder with 2qts of fresh brake fluid, remove the stock brake reservoir cap and replace with the Power Bleeder's cap, pump the Power Bleeder to 20psi (a pressure gauge is built in), open the bleeder screw to flush out the old fluid (using the included clear hose) into a waste container until it runs clear and bubble free, close the bleeder screw and move to the next wheel. I didn't even have to remove the wheels, and was able to completely bleed the brakes in about 5 minutes!

When you open and close the bleeder screw be sure to use the proper size six point box-end wrench or a flare nut wrench. Do not use an open-end wrench as it may slip and round off the bleeder valve. On the 850, the front bleeders are 11mm and the rear bleeders are 9mm.

Volvo specifies you to jack up the front of the car while bleeding the brakes to allow air to rise to the master cylinder properly. According to Volvo the proper bleeding sequence on an 850 is:

1. Rear passenger
2. Rear driver
3. Front passenger
4. Front driver

When finished lower the car, remove the Power Bleeder, and top off the brake fluid if needed until the brake reservoir level is at the MAX line.

To clean the Power Bleeder you just rinse it out with denatured alcohol making sure to remove all brake fluid from the unit and it's hoses and parts (I ran some pressurized denatured alcohol through it to make sure I cleaned it out thoroughly).

The end result was a nice firm brake pedal with no sponginess whatsoever. And because the Power Bleeder keeps the fluid receiver full the whole time without refilling, you won't have a problem with the brake receiver running empty. This makes the Power Bleeder truly a one man job. It can even do your hydraulic clutch too! What a time saver!

The beauty of the Power Bleeder is that it can be used on all of your cars, which is where the cost savings really adds up. Using Speed Bleeders it would cost me $30 per car. The Power Bleeder works on most European cars including Alfa Romeo, Audi, BMW, Fiat, Mercedes, Peugeot, Porsche, Renault, Saab, VW, Volvo, and all other cars with 45mm threaded reservoir caps. For Volvos, it fits 1968-present Vintage Volvos, 200, 700, 900, 850, x70 series, S60, and S80. It doesn't fit 40 series models though.

We do not sell the Power Bleeder and are not affiliated with Motive Products. We are only sharing our experience because it works, and products that make tasks like bleeding your brakes easier are worth recommending to others!

Happy Bleeding!