Trashdatsun Posted October 16, 2013 Report Share Posted October 16, 2013 Every time I step on the brakes the idle drops and it runs like crap, if I step hard it tries to die, especially when it is cold. It runs great other wise... is my M.C leaking into the booster? Quote Link to comment
datzenmike Posted October 16, 2013 Report Share Posted October 16, 2013 The master is separate from the booster. One hydraulic, the other is vacuum. Vacuum is stored in the booster. When brakes are applied the vacuum is applied to a diaphragm connected to the master push rod to help pull it on as an assist. There may be a leak. With engine off, pump brakes to remove any stored vacuum. Apply brakes and start engine. Pedal should drop towards the floor slightly is the system is working properly. Quote Link to comment
GRpufnstuf Posted October 16, 2013 Report Share Posted October 16, 2013 Maybe the vacuum check valve to the booster? Quote Link to comment
datzenmike Posted October 17, 2013 Report Share Posted October 17, 2013 It's a one way valve. Closes when engine shut off, some vacuum is stored in the booster, but not much. Quote Link to comment
Trashdatsun Posted October 17, 2013 Author Report Share Posted October 17, 2013 Thanks for the replies, everything seems to be in order, the pedal drops slightly when the truck is started, the brakes function as they should... so vacuum leak must be the problem and I suppose it must be in the valve... thanks again guys. Quote Link to comment
Z-train Posted October 17, 2013 Report Share Posted October 17, 2013 More than likely,Mike is correct.But there is a chance it's a mixture issue. Quote Link to comment
Trashdatsun Posted October 17, 2013 Author Report Share Posted October 17, 2013 Anyone know of a good place to get a new booster?... and thanks for the advice, it is nice to have a place to go with these questions. Quote Link to comment
]2eDeYe Posted October 18, 2013 Report Share Posted October 18, 2013 You can get them from a parts house or J/Y Quote Link to comment
Z-train Posted October 18, 2013 Report Share Posted October 18, 2013 Anyone know of a good place to get a new booster?... and thanks for the advice, it is nice to have a place to go with these questions.You tested and know it's the booster or are you throwing parts at it? 1 Quote Link to comment
Trashdatsun Posted October 18, 2013 Author Report Share Posted October 18, 2013 I guess i am throwing parts at it... I have no place to work on it and it is my only form of transportation. The booster is original and I already have a new MC,... seems like the right course of action. What do you think I should do? I am asking this sincerely, there is no sarcasm or ego in my question. Quote Link to comment
datzenmike Posted October 18, 2013 Report Share Posted October 18, 2013 Check the vacuum line to the booster for splits or loose clamps. Quote Link to comment
GRpufnstuf Posted October 18, 2013 Report Share Posted October 18, 2013 Yes, I'd start throwing new vacuum lines and intake gaskets everywhere b4 a booster. New ones are 200+ from what I've seen. My rule, if I'm using the scatter gun repair method, is start with the cheap stuff. Quote Link to comment
Z-train Posted October 18, 2013 Report Share Posted October 18, 2013 Un-hook the booster and cap the fitting on the manifold.Drive the truck. The pedal will be a bitch to push but it will stop the vehicle. If your issue is solved, then you have your answer.If not,you would have spent a bunch of money & time for nothing. 2 Quote Link to comment
Trashdatsun Posted October 19, 2013 Author Report Share Posted October 19, 2013 You guys rock, thank you, I will do all of the above. Quote Link to comment
Stoffregen Motorsports Posted October 19, 2013 Report Share Posted October 19, 2013 Anyone know of a good place to get a new booster?... and thanks for the advice, it is nice to have a place to go with these questions. Rock Auto has them for $96. http://www.rockauto.com/ Quote Link to comment
datzenmike Posted October 19, 2013 Report Share Posted October 19, 2013 My 620 (with the pathetic 35 amp alt at the time) would dip the idle slightly when the brakes were applied. Just the load on the alt.when all the lights were on. Hardly noticeable really. Quote Link to comment
GRpufnstuf Posted October 19, 2013 Report Share Posted October 19, 2013 Rock Auto has them for $96. http://www.rockauto.com/ Wow they have my '73 booster listed for $99 or $142. Almost worth it just to get a nice shiny one in there. Quote Link to comment
Trashdatsun Posted October 28, 2013 Author Report Share Posted October 28, 2013 It was simply a vacuum leak and you guys saved my ass. Thank you all. Quote Link to comment
daderaide Posted November 1, 2013 Report Share Posted November 1, 2013 My truck it doing the same thing that you've described. Where did you end up finding the leak? was it just in the booster hoses? Quote Link to comment
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