Re: Bendix Treadle Vac Study- Serioius Business!!
Posted by HH56 On 2011/6/7 20:03:55
What does that mean silicone sealer in the return channel?
There is a port in the casting between the reservoir and the space between hydraulic seal and vacuum seal. Its purpose is to let fluid go back to reservoir if hydraulic side leaks and if vacuum side leaks, allows it to suck air from vented reservoir. If blocked, there is nothing preventing a leaking vacuum seal sucking fluid or if hydraulic leaks, forcing the fluid into vacuum side. On yours that needs refilling, I wouldn't be surprised if you took it out and opened it up that you would find the vacuum side with fluid in it.
There are a number of gaskets in units possibly even from factory and in some rebuild kits which have that port covered or blocked because it appears the gaskets were designed for a different cover than Packard used so the same problem.
There is only the one big spring inside vacuum side pushing against the vacuum piston to return the pedal. If nothing is binding on the carpet or pedal side, then possibly the vacuum piston has been greased with improper lube and that is sticking or the spring has broken or become weak. If the leaking unit is the same one that sticks, perhaps it has got brake fluid in it and that is gumming up the leather seal on the power piston.
Here is a picture of the reservoir showing the port. This one has it open to reservoir, on later models with the gasket problem, the port opening is solid all the way to bottom of lid where gasket seals it.
Attach file:
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There is a port in the casting between the reservoir and the space between hydraulic seal and vacuum seal. Its purpose is to let fluid go back to reservoir if hydraulic side leaks and if vacuum side leaks, allows it to suck air from vented reservoir. If blocked, there is nothing preventing a leaking vacuum seal sucking fluid or if hydraulic leaks, forcing the fluid into vacuum side. On yours that needs refilling, I wouldn't be surprised if you took it out and opened it up that you would find the vacuum side with fluid in it.
There are a number of gaskets in units possibly even from factory and in some rebuild kits which have that port covered or blocked because it appears the gaskets were designed for a different cover than Packard used so the same problem.
There is only the one big spring inside vacuum side pushing against the vacuum piston to return the pedal. If nothing is binding on the carpet or pedal side, then possibly the vacuum piston has been greased with improper lube and that is sticking or the spring has broken or become weak. If the leaking unit is the same one that sticks, perhaps it has got brake fluid in it and that is gumming up the leather seal on the power piston.
Here is a picture of the reservoir showing the port. This one has it open to reservoir, on later models with the gasket problem, the port opening is solid all the way to bottom of lid where gasket seals it.
Attach file:
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