PM pressure switch replacement

[MSDGN]

For anyone who has replaced the PM pressure switch...how much did you tighten it when putting it in?...real tight...snug...or torque to specs...I've tried snug and also torqued to spec but can't get it to seal...I get a little brake fluid seepage at the base of the switch where it meets the MC...have tried two different switches but it still leaks...why isn't it sealing?

 

[subtlt]

leaking switch

Is the O-ring there?

http://www.gnttype.org/techarea/brakes/powermaster.jpg

 

[MSDGN]

Yep...2 brand new switches with O-rings in place...maybe I damaged the MC somehow when I rebuilt it...but have no idea how or what I could have done to it....just strange that both cars are leaking exactly the same...only thing in common is I rebuilt both units with all new parts...

 

[strikeeagle]

Did you lube the o-ring with some clean brake fluid?

 

[strikeeagle]

Also, make sure everything is pristine - a q-tip or two couldn't hurt...

 

[MSDGN]

Yep...cleaned up the threads/hole with a Q-tip...lubed the O-ring...torqued the switch to spec(manual says 15-20 ft lbs)...I tried 15 first...drove it a few times...fluid was seeping out...
cleaned it up around the base where it was leaking then snugged it to 20 ft lbs... this time could see fluid seeping a few minutes after turning the ignition on to pressurize the system...so
I snugged it up a little more thinking it might not be tight enough but it seemed to seep a little faster the more I tightened it...
guess I could be pinching the O-ring...very strange problem...that's why I was asking how tight you guys go when replacing them...I've replaced accumulators many times which have basically the same O-ring as the switch and never had one leak...could the O-rings on these new switches be the wrong size?

 

[strikeeagle]

Compare to old o-ring???

 

[MSDGN]

Don't have it...I chucked the old switch when I rebuilt the unit...