Old Man Posted February 23, 2023 Share Posted February 23, 2023 Replaced leaking knob with new one and still leaks out of bottom of knob from the bottom hole in the image. Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/ Share on other sites More sharing options...
Popular Post terry Posted February 23, 2023 Popular Post Share Posted February 23, 2023 Probably have a cylinder leaking, letting air leak out the shifter. Terry 2 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/#findComment-525910 Share on other sites More sharing options...
mrsmackpaul Posted February 23, 2023 Share Posted February 23, 2023 Or the pressure regulator is set to high Paul 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/#findComment-525911 Share on other sites More sharing options...
Solution Joey Mack Posted February 23, 2023 Solution Share Posted February 23, 2023 I'm with Terry. A bad oring in a shift cyl. Will bleed through and come out the shifter. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/#findComment-525913 Share on other sites More sharing options...
Old Man Posted February 23, 2023 Author Share Posted February 23, 2023 (edited) Are you talking about the slave valve on top of the transmission or is this cylinder located elsewhere? Edited February 23, 2023 by Old Man Needed clarification Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/#findComment-525918 Share on other sites More sharing options...
Joey Mack Posted February 23, 2023 Share Posted February 23, 2023 Check the one at the rear. You will need to pull the small top cover off to remove the fork bolt. Then you can slide the rear cylinder off as a unit Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/#findComment-525922 Share on other sites More sharing options...
MACKS Posted February 23, 2023 Share Posted February 23, 2023 Had this problem on my 12 speed,it was the o rings in the shift cylinder on top of the tranny,see if u can get an o ring kit for it before taking it apart,mine were very hard to match up,I did it twice to install the correct o rings.. Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/#findComment-525925 Share on other sites More sharing options...
fjh Posted February 23, 2023 Share Posted February 23, 2023 1 hour ago, Joey Mack said: Check the one at the rear. You will need to pull the small top cover off to remove the fork bolt. Then you can slide the rear cylinder off as a unit Troubleshoot! Remove front tube on the cylinder see if air is passing the oring inside first! Apply air to the back !Just sayin! 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/#findComment-525931 Share on other sites More sharing options...
Joey Mack Posted February 23, 2023 Share Posted February 23, 2023 luckily he has a T-2090... The oring kit is the same as the other Mack tranny's of that era.. Yes he should order them first. Good call MACKS.... 2 Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/#findComment-525932 Share on other sites More sharing options...
Joey Mack Posted February 23, 2023 Share Posted February 23, 2023 FJH, you are correct sir.. troubleshoot first... I was acting like I was doing the repair and I would just re-ring the cylinder anyway.. Ive done so many of them that its no biggie.. But you are right.... troubleshoot first.. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/#findComment-525935 Share on other sites More sharing options...
fjh Posted February 24, 2023 Share Posted February 24, 2023 2 hours ago, Joey Mack said: FJH, you are correct sir.. troubleshoot first... I was acting like I was doing the repair and I would just re-ring the cylinder anyway.. Ive done so many of them that its no biggie.. But you are right.... troubleshoot first.. yup the trouble shoot is easy confirmation of the Odvious is always good!The oring kit is an easy fix is Long is it’s the old style piston not so easy if it has the new piston an nylon type seals! 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72534-shift-knob-leaking-air-99-ch613-9-speed/#findComment-525946 Share on other sites More sharing options...
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