Air suspension

tinytom · 11-08-2008, 04:49 PM

I noticed that when my Alpine is parked in the garage for a week or longer the air suspension on the passanger side is completly evacuated while the driver side is not.

Is this normal. I never noticed it before

tinytom · 11-08-2008, 04:49 PM

I noticed that when my Alpine is parked in the garage for a week or longer the air suspension on the passanger side is completly evacuated while the driver side is not.

Is this normal. I never noticed it before

big jimbo · 11-08-2008, 05:32 PM

Assuming your garage is level, I would guess something is leaking, or otherwise out of adjustment.

zinom · 11-08-2008, 08:45 PM

I have the exact same problem; and with mine, parked in front of the house, it looks bad so I pump it back up. I have checked and tightened all connections' I could get to, at the bags and ride height valves. Is there a check valve somewhere downline that might have failed? Does anyone have an air line schematic?

Algoma · 11-09-2008, 06:09 AM

I wouldn't start up the engine just to re-inflate the suspension. In fact what I do is dump the air if I park for any length of time. This keeps the coach level and lowers the entry step.

Rick Coleman · 11-09-2008, 06:47 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Algoma:
I wouldn't start up the engine just to re-inflate the suspension. In fact what I do is dump the air if I park for any length of time. This keeps the coach level and lowers the entry step. </div></BLOCKQUOTE>I've always done that, but very recently an RV service tech told me not to do it unless the jacks are down because it is possible to cause problems with the air bags. He thinks the upper and lower air bag mounts can put undue pressure on the bags perhaps causing a puncture or tear. Anyone know for sure?

EngineerMike · 11-09-2008, 06:54 AM

IMO dumping the air is better than periodic re-inflating as a work-around for this problem. Your air dryer takes time to warm up and start working; it has an electric heating element to dry the air at least to start, but that takes time to hit efficiency, so frequent short operations of the engine's air compressor will put moisture into the air system that stays, which isn't optimum. Ditto w/short engine op's; you don't hit steady state operating temp so combustion isn't optimum & cataclysmic converter isn't working (both accumulate moisture if cycled for short run times). Cycling of dry air (and proper temp combustion gas) over several highway miles cycles new moisture back out, so start-then-drive keeps your air system dry as a rule and engine/exhaust systems clean.

There is a leak somewhere that can be found by using a soap solution on connections starting at the bag, then working toward the air compressor. Obviously it isn't bad enough to affect highway ride or you'd notice the listing to one side.

Algoma · 11-09-2008, 10:57 AM

Rick,
If you are parked on level ground the jacks don't do anything. They touch the ground but don't lift the coach at all, so I don't see the tech's argument here. I guess you could manually force the jacks to lift but I have never seen that recommended.

My understanding is that the front and rear suspension are somewhat separated as they operate at different pressures. If there is a leak surely it should only affect one corner or maybe the front or rear but I don't see how a leak could cause the front and rear on one side to go down.

dgerstel · 11-12-2008, 08:54 AM

Tom,

I have had a problem with air loss from the left front while parked for a few days. I haven't checked it yet as I am normally on jacks. I plan to check for leaks with soapy water from the air bag to the ride height control. Any leak behind the valve should not affect any wheel unless there is a leak in the valve. The air comes in from main supply, thru the ride height control valve, thru the air dump valve and to the air bag. If there no leaks in those areas I will deplete the air from the main system thru the drain valve in the rear, then take the "air in" line off of the ride height control and see if there is any leak thru the valve it self.

John,

I am quite sure that the air pressure in the system is the same every where. The air pressure in the bag is dependent on the pressure required to keep the bag at a certain height. This is accomplished by the ride height control. The ride height control just opens, allowing air into the bag when the height is too low and vents air when the height is too high. Most Alpines have a ride height control for each wheel. I don't know for sure, but think that the real early coaches may only have one per axle.