eric787 Posted September 12, 2023 Share Posted September 12, 2023 Got a 05 mack granite and the other day the primary air stopped working any thoughts? looked at it quick it was pumping air into the dryer the secondary will fill up but not the primary. Any input will be appreciated thanks. Quote Link to comment https://www.bigmacktrucks.com/topic/73296-primary-air-not-building/ Share on other sites More sharing options...
67RModel Posted September 12, 2023 Share Posted September 12, 2023 I guess it could be one of two things. Either the gauge is broken/sprung and the primary really is functioning normally or the one way check valve at the inlet of the primary system has failed in such a way to not allow air to flow into the primary system. Does the truck have a supply tank (wet tank) between the air dryer and the Primary / secondary reservoirs? Find the line that goes from the wet tank to the primary supply tank and trace to find the one way check valve. Does the low air alarm stay on constantly? If the compressor is pumping fine and the secondary system is filling up fine I don't know what else it could be other than the one way check valve on the primary side or a catastrophic air leak between the wet tank and primary supply tank you can't hear because the truck is running. Or a broken gauge. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/73296-primary-air-not-building/#findComment-538730 Share on other sites More sharing options...
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