[Rodney]

I assume you are talking about the Marathon aux air tank not the Prevost air tanks.

In our bus, the Marathon aux air tank is in the compartment below the driver. It is just one of those 6 gal pancake tanks. It should be drained regularly just like all the other air tanks. Access to the drain valve requires crawling partially into the compartment. That might be the reason why many people don’t bother draining it.

It might also be accessible by dropping the front bumper. Haven’t tried that yet.

It should last a long time if you drain it regularly.

Gerald

[Steve]

Our tank is right above the DS front wheel. Drain valve is at the front of the generator compartment–easy to get to.

[Archived]

Air tank corrosion is a problem that can impact any coach and the only prevention is to keep moisture from the tanks to the extent possible.

Different conversions are plumbed by the converter to use a dedicated accessory air tank or the Prevost installed accessory air tank. Both are likely to be receiving moisture because most conversions do not have a capable air dryer to prevent the accumulation of moisture and most owners have been unaware of the need for air system maintenance.

The question is excellent because it brings this issue out and all owners should be aware that if they do not understand how their accessory air system is set up, they should learn how it is, learn how it is protected from moisture, and learn how to maintain it.

The presence of moisture in our air systems not only affects the life of the air tanks, but it is damaging to the number of valves and devices within the system and remediation can get very expensive, very fast.

[Tim]

If your Marathon has a separate aux tank, not sure your vintage does, chances are it’s rusted and nasty. I had a 97 Marathon and don’t recall if it had a separate tank.

[John]

I am fortunate to have purchased my coach from someone that took extremely good records and had most, if not all, the original documentation. I found this illustration the shows 6 air tanks. Is the tank the Accessory tank or the Secondary tank? Thanks

[Archived]

[Brian]

Everyone needs to understand that all Prevost drawings and diagrams are of unmodified coach shells. They will not include anything added or modified by the converter.

The importance of understanding that cannot be overstated because the house systems where they connect to the chassis systems should be limited to the points Prevost provided for air or direct current electric. Other than those points the house should be completely isolated from the chassis. Some conversions had other interfaces and in the case of those conversions the responsibility for repairs or maintenance gets a little fuzzy because it gets much more difficult to isolate and deal with issues.