PPV valve replacement does seem to solve the problem

[ralphluby]

I have a 1993 M923A2. The air pressure relief valve (65 psa) to the brakes keeps releasing air on a periodic basis. I have just replaced the PPV valves with a Haldex L31258 (equivalent to a 90555396) with no change in the relive valve releasing air.. My primary and secondary dash gauges read at about 90 psi. Would I be correct in assuming that the problem is with my governor adjustment or a faulty governor. If is the governor what what would be a correct replacement number.

 

[The HUlk]

I have a 1993 M923A2. The air pressure relief valve (65 psa) to the brakes keeps releasing air on a periodic basis. I have just replaced the PPV valves with a Haldex L31258 (equivalent to a 90555396) with no change in the relive valve releasing air.. My primary and secondary dash gauges read at about 90 psi. Would I be correct in assuming that the problem is with my governor adjustment or a faulty governor. If is the governor what what would be a correct replacement number.

You can remove the small air line that goes into the top of the compressor(unloader valve) to rule out the governor. If it still wont build past 90psi with this line removed then the governor is not the problem.