air rapidly decreases with brake application

[neil omalley]

Title pretty much sums it up. Exiting Ocracoke,NC ferry, my warning horn was telling me pressure low. Managed to get off ferry and was able to rev the engine and shut off the horn and increase the pressure. Within a mile the pressure dropped off and the horn started again.  Pulled into a camp site and leveled the coach. It stayed level all night and this morning when I started the engine the horn was blaring (as it usually does) and took a LONG time and increased acceleration to bring the air pressure up to necessary poundage. This situation came on suddenly. Nothing suspicious all day driving and as far as I know nothing got scraped or dragged entering or exiting the ferry. Suggestions as to where to begin to look? Thanks.
p.s. and of course the weather here on the East coast is grim. Does it happen any other way?

[Karl Welhart]

Neil,

You need to find this problem ASAP.  Sounds very serious and IMHO you should not drive the coach until the source of the leak is found.  Most likely an air line, air valve or air bag.  I would find a shop that can hook up an air supply line to your coach air supply line.  Then you should be able to hear the air leaking out under the coach.  This will give you a place to start looking for the leak....

[Paul Schwalen]

Neil,

As Karl stated you need to get the RV to a shop. Last year I experienced similiar symptoms, rapid loss of air and had to keep the rpm's up to have any braking power.  Made it to the local Ringpower (about 17 miles)  and they found a bad air chamber on the rear axle.  They reccommended changing both so I did and the cost was about $450.  No problems since and happy for that.

Good luck.

Paul

[Lee Welbanks]

Well if its leaking air that fast you will be able to hear it, could be almost anything in the air system. Hose to rear brake cans, air valve, air line to one of the tanks. Get the air pressure built up and get out and listen to try and figure out where the leak is.

[Joel Ashley]

The air leveling and air ride, though related, are different systems.  Since your leveling stayed up after using tank pressure to get it there, I'd consider that the air pump/dryer side may be the culprit, rather than a leak.

But I'm hardly an expert on the air systems, so hopefully others more familiar with that aspect will add to the discusssion.  As I understand it, the braking system has first dibs on air;  nevertheless, it should be checked asap.

-Joel

[Lee Welbanks]

Does your air only drop when you apply the brakes, (brake pedal)  If so you have a leak in your service brake side, could be a hose or a diaphragm blown in one of your brake cans. Could be a service valve but usually its a diaphragm or hose. If its a diaphragm you will hear air leaking out of the brake can when the brake pedal is applied or a hose, should be able to hear that big a leak.

[neil omalley]

Thanks all. I was able to get the air up today. Seemed like I had to rev the engine more than usual (Could be anxiety over the issue and where it was occuring). I was able to drive all day without undue revving of the engine to keep the air up.  I will ,of course, have it inspected first available and what I am now suspecting that boarding the ferry I was required to use the brakes on and off and the engine was not able to run long enough or hard enough to get the air back up before I needed to brake again. Always sump'n !

[Lee Welbanks]

Thanks all. I was able to get the air up today. Seemed like I had to rev the engine more than usual (Could be anxiety over the issue and where it was occuring). I was able to drive all day without undue revving of the engine to keep the air up.  I will ,of course, have it inspected first available and what I am now suspecting that boarding the ferry I was required to use the brakes on and off and the engine was not able to run long enough or hard enough to get the air back up before I needed to brake again. Always sump'n !

With your parking brake released air pressure up, engine off stomp on you foot pedal as hard as you can. Now what happens to your air pressure, should drop some when you apply the brakes then hold at that pressure. If it continues to drop you have a leak in your service brake side, get it repaired before you drive anywhere, because if your going down the road and your pressure drops below about 60 psig your maxi brakes will apply and slap you through the windshield, you will come to a skidding halt right where your at.

[neil omalley]

Thanks Lee. Will check first thing a.m.