ndeli55 Posted July 7, 2008 Share Posted July 7, 2008 ok i have a 73 240z, and it has been sitting for some time. i have recently tried to rework the brakes, rebuilding the two rear wheel cylinders and replacing the master cylinder with a reman. the problem i am having seems bizarre and after searching i havent found anything similiar to my symptoms. i pressurized the system using a power bleeder but found no flow at the wheel. when i opened the bleed valve at the calipers and wheel cylinders nothing. not even a spit. now if i open the master cylinder bleed lines i get plenty of flow. also i pulled the actual break line at the master cylinder and there was flow as well, now when i pulled the break line after the proportioning valve, nothing. is the proportioning valve the problem? or is something else at play? any help would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 7, 2008 Share Posted July 7, 2008 You have a blockage in the lines somewhere. I'd pull the wheel cylinders off and stand on the brake pedal and see if you can bust it loose. Then run a bunch of fluid through the lines so that you hopefully get whatever it is out, then hook up the wheel cylinders and bleed as normal. Alternatively you could pull the brake lines off and clean them out off of the car, or just replace them. Quote Link to comment Share on other sites More sharing options...
ndeli55 Posted July 8, 2008 Author Share Posted July 8, 2008 is it possible that the blockaged is actually in the proportioning valve? is that common? for as i stated before the flow is inhibited directly after this valve. if so where can i find a new one? or should i just put a t fitting on the front brakes and a proportioning valve on the rear brakes? any adverse reactions to this solution? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 8, 2008 Share Posted July 8, 2008 is it possible that the blockaged is actually in the proportioning valve? is that common? for as i stated before the flow is inhibited directly after this valve. if so where can i find a new one? or should i just put a t fitting on the front brakes and a proportioning valve on the rear brakes? any adverse reactions to this solution? Please try to use proper capitalization. You said you tried at the master and at the wheel cylinders, and the proportioning valve. The clog could be anywhere between the master and the prop valve. Is the prop valve in the 73 in front or in back? If it's in back, there is a lot of line in between. If you pulled the line going into the prop valve and got flow, but got no flow out, then you could say that the valve is the culprit. Not sure about the later prop valves, but the early ones can be disassembled and cleaned. Don't remove it. The valve is there for a reason. It reduces the line pressure to the wheel cylinders. If you take it out, you'll have more line pressure at the wheel cylinders, which means that you may lock up the rear brakes before the fronts. Locking the rears first is a good way to spin the car. Nissan engineered that valve to work with that braking system. You should not remove it unless you replace it with another proportioning valve from a like system, or an adjustable one. Quote Link to comment Share on other sites More sharing options...
ndeli55 Posted July 9, 2008 Author Share Posted July 9, 2008 Yes, it is on the firewall. thanks for the help. I just didn't know if that was likely cause, or if it was common. Thanks again. Quote Link to comment Share on other sites More sharing options...
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