LloydW Report post Posted October 5, 2015 i have an 05 beaver with a C9 Cat engine. It looses up to 50 lbs air pressure overnite some times a little less some times a little more. All of the obvious fittings etc have been checked. When it was recently serviced I had the mechanic check and he was sure it was leaking back through the compressor. I then took it to truck shop for repair they claim not the compressor but can't find the leak.does anyone have any ideas? thx lloyd Share this post Link to post Share on other sites
rlbarkleyii Report post Posted October 5, 2015 My Freightliner Chassis XC under Journey always discharges air when motor is off and the chassis is no longer in travel mode. ( air bags deflated) It takes several hours to bleed down. Are you talking about a slow bleed down? Do you have a air drier? Many air driers are designed to blow off moisture when engine is not running to get water out of system. Does you compressor cycle when running? Does your service tank stay at 120 psi with motor on, does it recover quickly after brake application. Most of us would need more info to help you! Share this post Link to post Share on other sites
wolfe10 Report post Posted October 5, 2015 VERY unlikely it is a compressor-- there is a check valve in the air dryer that should prevent this. Let's start with a routine maintenance item-- how old is your air dryer. They should be serviced every 3-4 years in an RV application. I find factory reman (i.e. the factory that made them, not cheap knockoff) a very good idea, as all check valves, heater, etc are new in addition to the filters. Other than the dryer, it is a matter of checking all connections with soap to see what bubbles. A common leak is the quick release where you could connect an air line. If so, just install a ball valve prior to it. Share this post Link to post Share on other sites
LloydW Report post Posted October 5, 2015 Thanks guys I will make sure the shop checks the dryer. It is a fairly slow leak and I can't hear it. I think all of the connections have been soaped. Share this post Link to post Share on other sites
LloydW Report post Posted October 5, 2015 Thanks for the input, I just got a call from the repair shop they found the leak. It is on the manafold block by the rear suspension. Share this post Link to post Share on other sites
wolfe10 Report post Posted October 5, 2015 Lloyd, While it is there, I would still recommend servicing/replacing the air dryer with a factory reman unit as good Preventive Maintenance. I have seen a couple of coaches (I do mechanical inspections on coaches) where the desiccant failed and there was white desiccant powder throughout the air system. This can require very expensive repairs-- basically it messes up the check valves, ride height valves, air brake components, etc. Share this post Link to post Share on other sites
bm02tj Report post Posted October 15, 2015 My air drier was nasty when I changed the filter. The shop that I had servicing never told me about it. I learned that here-- read and learn with the rest of us. Share this post Link to post Share on other sites
