QuestionHi Dick
This question applies to any car,truck or machine that has a hydraulic system.
There are the vacuume type systems,pressure tank systems & the old stomp on the paddle method of ridding the system of air. I have them all & have always wondered which works the best. I worked for a time on Nascars & sprint cars & midgets. We just used the stomp method of: up - down, open - close. I had heard of a method of using gravity over night with a reservoir of fluid to keep the system full as it dripped out of the bleeder screws.
I have been working on cars & such for 40 years as a hobbyist but this question has always plagued me.
Lookin foward to hearing from you.
I heard about this in Skinned Knuckles.
Best Regards
Mike Ready
AnswerAh, another fan of Skinned Knuckles!
I am in pretty much the same boat as you - I also have used all three traditional methods, and I suppose the best results I have obtained have been with the pressure bleed system. My only frustration with the pressure bleeder I have (which is a Snap-On) is that I never seem to have the right master cylinder adaptor - probably because I work on so many really odd cars.
I've cured this problem by taking a spare master cylinder cap from each of the cars I work on, and modifying it by drilling out the vent hole large enough to accept a normal tire valve - the bolt through type such as you'd find on a motorcycle rim. Then I set my shop pressure regulator at about 30 PSI, and supply that pressure to the master cylinder. Then I crack open each bleeder and let a few ounces of fluid come through. After each two bleeders, I have to stop and top up the master again, so I don't put air into the lines, but this is a small price to pay for not having to keep an extra gallon of fluid in my pressure bleeder, and not having to futz with the jillion different master cylinder tops I deal with.
I bought a vacuum type bleeder and found it very unsatisfactory - I always had trouble getting a good vacuum on the system, either due to the leakage around the bleeder screw threads, or due to a poor fit on the bleeder nipple. Then the vacuum pump failed due to it having injested some Dot 3 fluid, so I threw it in the trash. What a dumb choice of material! I had used it a few times on Silicon fluid, which I prefer in the cars that are seldom driven, so I didn't realize it was made of plastic that couldn't tolerate alcohol. What a piece of junk!
The gravity system seems too simple to beleive, but I admit I've never tried it. It must be very slow!
The 'pump the pedal' method works fine on the old single circuit systems, as long as a helper knows what to do and when to do it, but the dual master cylinders sometimes won't bleed thoroughly unless you use pressure.
Not sure this is any help, but it's all I know.
Dick
