Community Forums

AKOne · 07-17-2018, 06:41 PM

Been reading about air dryers. Given (most) Alpines do not have air brakes, how often should the air dryer purge (blow/pop-off) air?

twinboat · 07-17-2018, 07:00 PM

Sitting still, it shouldn't purge for at least 15 minutes or so.

If you have air suspension, the movement traveling down the road, will use some air. As the suspension adjusts, air is used and discharged to maintain ride height.

The Alpines I've read about do have air assisted hydraulic breaks. There are air chambers that push the master cylinder, when you step on the pedal.

Old Scout · 07-17-2018, 08:31 PM

…..not so much -- only a very small number of Alpines were built with traditional air brakes....none that I know of ever had air over hydraulic....as for air dryer maintenance--air volume is not as much of an issue for Alpines as age....its been suggested that the internal desiccant cartridge can rupture with age and contaminate the air system....so perhaps change the cartridge every 5-6 years or may be before 10 years?????? ….sure others will have opinions.....

c_oneil · 07-18-2018, 05:37 AM

From my experience it varies a lot depending mainly on how bumpy or winding the road is. Standing on level ground with engine running and E-brake not engaged I would say 15 minutes or more is good. On a very smooth straight road 6-8 minutes is good. On a very bumpy winding road less that 3 minutes sometimes. My coach has the Haldex "IR" (instant response) style ride height valves that use a little more air than the "CR" (controlled response) style. Your coach may use the CR valves. Not too sure on that. You may not have the variable turbo that uses some air too.

wolfe10 · 07-18-2018, 06:27 AM

Yes, the vast majority of Alpines have hydraulic over hydraulic brakes.

A very few have regular air brakes.

None have air over hydraulic.

Old Scout · 07-18-2018, 06:31 AM

…..not sure about IR Vs CR but no variable pitch turbo on a 99...that feature began with the Pegasus engine on a 2005.....

Old Scout · 07-18-2018, 06:51 AM

...having said what I said about brakes on Alpines--I try not to say "never" or "always" when it comes to Alpines. In particular, this applies to the short-run production Avalanche. Pretty sure they had traditional air brake drums in rear but not sure about the front axle--but again, pretty small sample size here....

AKOne · 07-18-2018, 09:11 AM

The reason for mentioning air brakes was due to Alpines difference in demand for compressed air as compared to coaches with an air brake system. Sometimes reading various iRV2 posts things get confusing. Hence my post/question. Since Alpines have a somewhat different air system, I am try to gain a sense as to what is normal or typical purge interval for the air dryer. Based on the responses, what I need to do is park on level ground, chalk the wheels, e-brake off and time the intervals between purges.

Admittedly, this is the first diesel I have owned. So I am working on my education regarding systems like the air dryer, air governor and compressor. What needs maintenance and how often, how it functions and what is normal in order to troubleshoot if it becomes necessary. Guys, all of you are a big help ... thank you!