air pressure on service side

Could be trailer air valve on the trailer?

 

Not sure about your specific problem. Just a caution. Maybe you already know this, but a lot don't. The spring inside a MAXI can take your head off very easily if you are not careful.

 

Very True. Needs to be caged before you remove it.

 

Air is leaking through the center seal from the park brake side. To confirm this, pull out your yellow button, if the leak stops, that pot is no good either.

 

It could also be a stuck relay valve, or stuck brake pedal. Are your brake lights on all the time? You could take the lines off the other pots one at a time and to track down where it is coming from.

 

Good day Muff,
I am not totally sure what the problem is, but let me guess . you have air coming from the maxi s service side . so air flowing from the maxi? if this is the problem its a usual problem on old maxi that has had a few years of service. when you open the maxi you would see a piston inside the maxi. my guess is that the o ring, plastic ring, on this piston might be broken and thus bypassing the air. you have emergency side of the maxi leaking past into the service side and out the port back into the service system. when engaging the park brake you should find the leak is gone. I usually never fix a maxi as it can be very dangerous , so replace it with a new one rather. sometimes you will find when the park brake is released the load sensing valve or relay load sensing valve will continuously dump air. so to check if it is the maxi, just take a plier and squeeze close the service side pipes one after the other. when the relay stop dumping air you have found the troubled maxi.
hope this will help you.
G

 

o sorry heavyd nailed it , saw it too late apologies .