Community Forums

Spring1898 · 03-24-2025, 10:00 PM

Just moved the old RV and noticed what appears to be some oilish residue stain from under the RV near the front afterwards

I suspect it may be coming from the air brakes as the only other major thing in the area would be the generator which wasn't running.

I have never serviced or drained the tanks since I owned it, but previously it was supposedly dealer maintained. Is there a guide or a good video going over the drain and other basic maintenance steps? I hear there is a dehumidifier filter thing also.

d23haynes57 · 03-24-2025, 10:07 PM

The air tanks should be checked for water and drained after every use. If the dryer is really doing its job very little water should make it into the tanks. But again, they always need to be checked. Some rigs will have automatic drains and if really lucky the drains will be heated for winter. The drier has a desiccant filter that also needs some regular service.
Having water in the tanks can freeze and cause damage and if the water makes it into the valves and chambers things can go downhill fast.

Iceclimber · 03-24-2025, 10:39 PM

"The air tanks should be checked for water and drained after every use"

You are saying every time the coach is run you are supposed to get under and drain water from the air tanks ?

d23haynes57 · 03-24-2025, 10:56 PM

Yes! Unless there are auto drains. Surprising many of the higher end coaches do not have auto drains but the valves are remote and easily reached or there are lanyards.
When I took my road test for my license upgrade, I had to demonstrate the operation and testing of the air brake system including air testing for leak down, brakes applied and engine off.

Lowflyer1 · 03-25-2025, 02:14 AM

You can download an Owner's Manual from this link: https://www.monacocoach.com/service-...pairs/#manuals
It has pretty much all the info you need to maintain your RV.
In this case I doubt moisture in the tanks is the issue. You need to crawl under and inspect closer for the source.

On mine it says to drain the tanks once/month or more often if in high humidity conditions.

Yes, the "Air Dryer" will take most of the moisture out. On my manual it says to replace that every 2-3 years.

Spring1898 · 03-25-2025, 06:28 AM

Well I saw the tanks have bungs at the bottom which I suppose are for the draining. So I can open those. Are they supposed to have teflon tape or something put back on them?

Don't know where the dessicant pack is on mine but I presume it is back by the engine somewhere

gsgriffin · 03-25-2025, 06:36 AM

Quote:

Originally Posted by Spring1898

Well I saw the tanks have bungs at the bottom which I suppose are for the draining. So I can open those. Are they supposed to have teflon tape or something put back on them?

Don't know where the dessicant pack is on mine but I presume it is back by the engine somewhere

I would get a better read on exactly where the oil came from. If in a new location for a while, look before you move.

If you are in the southwest and staying in dry air, the tanks may never need to be bled. If traveling in humid and rainy conditions, open more often.

Your dryer filter is like a huge oil filter upside down (filter pointing up). Mine is in a side bay near the access for my primary fuel filter and hydraulic jack valves, but the color and volume of the oil might help direct you a little better.

SafariBen · 03-25-2025, 12:58 PM

The air brakes probably didn't make the oil stains as mentioned. The dryer could have blown off some oil and made the stain, but that would be one spot, near the engine typically.

The dryer needs to be replaced at some point, though if the compressor is in good shape, it can go a long time before causing problems. It regenerates every time the compressor runs, so if it doesn't get much oil it can run a long time before causing trouble. Oil comes from a worn out compressor...

The tanks should be checked regularly, whether that's every time it's run, or after every long trip, or SOMETIME. If there's never any more than a drop of moisture, then they don't have to be checked EVERY trip.

If you have manual petcock drains, there is no teflon tape needed, it's a brass on brass seal. You may need a crescent wrench to loosen them, COUNTERCLOCKWISE, then finger tighten clockwise after opening enough to blow any dirt out of the seat so it will close cleanly.