Disc Brakes on my Blue Bird

[Ron]

I own a 1990 BB with all hydraulic 4 wheel discs that I've had to replace a couple of brake lines on due to corrosion. Can anyone direct me to ther correct procedure to use when bleeding the brakes? These are not air/hyd brakes but rather electric boost and I haven't had any experience with them before. Any info would be appreciated

[Les Lampman]

Hi Ron,

I see you're a new member here. Usually this is a pretty talkative and responsive crowd; I didn't want the lack of response to your question to discourage you from hanging around. I've got air brakes so I can't help you at all; maybe someone with a setup like yours will chime in here in a bit.

[JonCBrand]

Basicly you need to start at the farthest wheel from the Master Cylinder because this is a rear wheel vehicle it should be set up with a front rear split system, most front drive have a diagonally split system (front righ, and rear left on same circuit). Anyway start with the LR then RR then LF then RF

Make sure that the Master reservoir is full of fluid and the cap is on.
Have a helper "pump up" the brake pedal a few times and hold it down. while the pedal is down open the bleeder slightly to allow a stream of fluid to exit. Watch for the spitts of air. Shut of the bleeder as soon as you notice the stream start to decrease. Repeat this proccess at each wheel until no more air is seen when bleeding.

That is how I bleed brakes at work.
PS. If you dont feel comfortable doing this dont hesitate to get help from a knowledgable, prefferably certified technician.

Jon

[Ron]

Thanks Jon,

Actually I got the job done last week after running in to a local tow truck operator in the autoparts store that has the same system on a couple of his tow trucks. I probably didn't explain myself very well to begin with but my concern was over the electric booster because with this system, the pump on the master cylinder runs when the pedal is depressed and doesn't shut down if there's air in the system. I was worried about causing damage to the pump by having it run excessively and possibly dry. I ended up disconnecting the battery and bleeding the brakes normally as you suggested. Then when I reconnected the electrics, the system worked as normal.

[JonCBrand]

Hey sounds good as long as is stops and has good pedal feel.

I forgot to mention about the elec booster. I dont deal with those very often at the Chevy dealer.
Jon

[Ron]

Yup, I hear what you mean. Mostly what I get involved in is 70 to 100 ton Cat and Komatsu trucks and 5 to 14 yard Cat loaders. The systems are a lot different than this old bus, but this works really well and we've had a lot of fun with it the past summer. My wife wants to take in a series of shows (dog) in and around the Florida Panhandle at the beginning of March so I've got more mods to do over the next few months.

Ron Johnson
http://www.elysianfield.com
mailto:ron@elysianfield.com