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marathon holding tank readings issues
GOOD MORNING. can anyone advise me on marathons holding tank readings. i replaced all the pumps last summer took trips all worked fair on the tank readings. the black tank has always beed lazy. now getting ready for a trip and checked the air lines and replaced ck valves. i get constant fresh readings grey holds for little time and black shows and dropps out quickly. i have soaped the lines and not finding any leaks. maybe not enough pressure to show up ? . any one know this marathon system or what it is ? any input would be good thanks.terry..
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7 Replies
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Does your coach have the headhunter tank monitor system? if so you may need to replace the o ring in the system. also not unheard of for a newer pump to be bad. i belief the o rings are a #78 that can be sourced from lowes or home depot and then maybe do a calibration. we have also had good luck replacing headhunter systems on coaches with plastic tanks with a see lvl tank monitors but you would lose the functionality of seeing the tank lvls at the marathon screen
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THANK you. not sure of any o rings on my older system. and i will try another pump but think they are good. i get the black to work shortly then go off again. this is an old 1998 system. hunted for leaks for awhile now.
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The system is complex is has several key pieces.
The 3 fish tank pumps blow air into the tanks (Black, Grey, Potable) through a tube in top. This tube has to be tight and sealed no air leaks. Just buy new pumps, new check valves, and tighten up this part of system.
The air blowing into tube is connect to a sensor made by Motorola or now called Freescale Semiconductors that takes the pressure input and converst it into a 0-5 volt signal. The pressure transducer is solder to a little board above water bay PAX side of bus (my bus not your).
The signal goes to Waterbay board in the 2nd Bay back my bus not yours in the ceiling. This computer board is scary…do not touch if you are not skilled in electronics or you mess up more then your tank levels.
The key thing is that there can be no air leaks in the system because it relies on pressure converted to electronic signal.
It reality the system was state of the art 22 years ago but by todays standards its POS.
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spot on ED. Thank you
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Replaced stand pipe in three tanks,
solve my problem, hope this helps
1999 XLV X-6872, liberty #440 -
good morning. I have the same system. I have fought it for seven years on and off. I found that good brass barbed couplers and good check valves to be important. to keep it working. mine now works really good but when the outside temps rise my black tank is on and off. when Brian Gabel and I reflashed my system he said my water board was reading a little odd but said as long as it was working no big deal. also I blow low air pressure into tank sensors that cleans the sensor and has helped. good luck. system maybe a relative to our air leak issues. HA HA.
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Not familiar with the marathon system, but sounds similar to the Headhunter system. I could not get my Headhunter system to maintain a constant level until I replaced the plastic pipe inside the tank. The original plastic pipe had become brittle over the years and had hair line cracks in it that allowed air to leak out. It was not an easy job to do, there was very little room to work. One of the pipes broke in the few places because it was so brittle. Thankfully the pieces were small enough that they flushed out when I dumped the tanks.
Chuck
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL
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