blacky

Here are two good write-ups:


http://www.s2ki.com/s2000/topic/9954...eding-revised/

http://www.s2ki.com/s2000/topic/9938...ravity-method/


Blacky adds:

1. For the HHR I recommend opening only one bleeder at a time.

2. Tapping caliper gently with a mallet may coax some extra bubbles to float up and out of the caliper.

3. In between service keep the reservoir topped up with clean brake fluid. This is obviously good for the system, and also provides some extra "sea room" should a leak develop on the road - maybe enough extra sea room to make it back to port.

Also, any sudden drop in level is more easily gauged from the max fill line than from some random level floating around between min and max.

Should also mention that brake fluid doesn't keep well after being opened. Every two years I gravity bleed. The year in between I pump out the reservior and top up with new fluid, thereby pretty much consuming the whole bottle.

Finally, on our HHR, the rubber seal on the reservoir cap had a slit in the bellows part - which obviously was a source of moisture. Expensive to replace due to very special rubber compound.

4. In addition to brake fluid doing its job absorbing moisture, the system always includes bits of rubber and plastic debris, and so on. The caliper bore is obviously a particularly likely place for moisture and debris. Therefore, if piston has to be compressed (say to replace brake pads), failure to open the bleeder means that the worst of the brake fluid is being forced back upstream.

5. Compared to inexpensive pressure bleeders, and certainly pumping the brake pedal, gravity bleeding is much less prone to introduce air into the system. Pressing the brake pedal beyond its normal range can also create debris, and even ruin rubber seals.

6. The question of mechanical damage due to compressing caliper pistons with bleeders closed, or using a pressure bleeder on the HHR, is at least debateable. The problem is that a mistake here could be very expensive.

7. Gravity, fluids, bubbles, and siphons are a lot of fun, and can provide a wonderful teaching moment for youngsters of all ages.

07azhhr

Don't forget that you should start with the one furthest from the resevoir.

blacky

Why?

843de

Mike was taught...got me doing it now blacky.

In theory, you start with the wheel furthest from the master cylinder because that is the longest brake line. Hence, it'll contain the most old contaminated fluid and air.

07azhhr

Thank you Mike.

843de

You might get some differing opinions on where to start bleeding brakes, but I was taught to do it back in 1975, and I still start at the farthest wheel.

Nowadays I use a power brake bleeder, that way I don't have to recruit my wife to pump 'em up and top off the reservoir.

Santa brought me one of these back in 2010.

http://www.motiveproducts.com/

07azhhr

It could very well just be an old school mentality to start at the farthest wheel. I was taught that not nearly as long ago as you were (late 80's) and then even reaffirmed when I did my apprenticeship at a GM dealership by a master tech. It was also a question on my ASE certification test for brakes. That was back in 2004.

blacky

I don't think the order is critical on the HHR. The main thing is to open only one bleeder at a time to keep a good flow going and avoid introducing air into a slower flowing caliper.

I bleed the driver side front first, because I assume that that is the shortest run. That way, I get as much of the contaminated fluid out as possible before doing the longer runs.

One thing that is ususally lost in this never ending debate is that there is no law against bleeding one or all calipers more than once. That way, you can treat your HHR to the best of all worlds.

jczboy

Actully most cars now days have a bleeding sequence. While I agree "Most cars" go from furthest to colsest, there are a few odd balls out there that don't, and will suck air if you don't. And it sucks to try to get a pedal after you get the trapped air. Pressure bleeders of vacuum bleeder would be required at that point. I can verify to see the sequence if anyone interested when I get to work tomorrow.
Just my 2 cents