Air Suspension questions

[Scarypat]

HI everyone,

Newbie here, and new owners (to us!) of a 2005 Newmar Kountry Club 3910 DP with a Spartan chassis. I need some info as to what is normal or not regarding overtime deflation of the air suspension when parked, so I don’t start chasing air leaks for nothing. At this time, our mh is still « stored » on an outside lot, but we do go there regularly to start putting the « permanent » glamping gear (kitchen stuff, bedding etc.) - about every week-end. I take the advantage to start both the genset and the engine (fast idling to bring it to temperature). We noticed that everytime we get there (as I said, every 7 days more or less), the suspension has completely deflated. Is it normal, or should I try to trace an air leak? It looks like the front is sagging more, but it’s hard to say of it’s because the back does not leak or if it’s just a suspension geometry thing.since I have not had a chance to inspect the back, and there is no need to confirm the deflation - the mh looks like a low rider…

Thank you in advance for your insights!

Patrick

 

[RayIN]

Unless the air springs are deflating in a few hours I wouldn't worry. This is the Spartan MM chassis air system plumbing, if it helps. When the engine is running and system is fully-aired up, does the air dryer purge function sound frequently, as in once in 2 minutes or less?

 

[Scarypat]

Unless the air springs are deflating in a few hours I wouldn't worry. This is the Spartan MM chassis air system plumbing, if it helps. When the engine is running and system is fully-aired up, does the air dryer purge function sound frequently, as in once in 2 minutes or less?

Thx for the graph! I’ll need to check the external hook-up fitting. Wondering if that fitting could be used to hook up an air hose to top up the tires?

Never put any attention to the matter, but as far as I know not often enough to notice. From memory, I hear it like a few minutes after starting the engine once the suspension is also up. I’ll pay full attention when I start it this week-end.

 

[Larry N.]

I'm with Ray, if you don't notice the deflation the same day (especially the first hour or two) and the pressure on both tanks is normal when running then you should be in decent shape.

 

[Gary RV_Wizard]

Ditto what the others said. A few coaches are sufficiently air tight to stay up a week or more, but 2-3 days is more common. There are a zillion air connections and each inevitably loses a tiny bit. I wouldn't start searching for leaks unless it went down overnight and even then it's not crucial. The onboard compressor can easily keep up with routine air use & loss whenever the engine is running.

Yes there will be an airline tap up front that can be used to add air to tires. Typically located in the area below the driver seat and accessed either from the left-front storage bay or the front cap opening (generator area). However, the air tap has a fairly wide pressure regulation band, something like 90-125 psi. This can make adding more than a few psi awkward.

 

[RayIN]

The intended use for the external hook-up is for when towing the MH is required. Then the tow truck supplies compressed air to air up the suspension and release the spring brakes.

 

[Utclmjmpr]

You should also place the jacks in the down position during extended parking,, allowing the suspension to remain in the fully deflated state is very hard on the air bags,, it causes them to remain in a wrinkled position and to crack along those wrinkles... I also have a Mountain Master chassis.. You are also NOT doing the main engine any good running it for brief periods,, It creates excess moisture in the oil,, diesels do not require frequent running..>>>Dan

 

[RayIN]

You should also place the jacks in the down position during extended parking,, allowing the suspension to remain in the fully deflated state is very hard on the air bags,, it causes them to remain in a wrinkled position and to crack along those wrinkles... I also have a Mountain Master chassis.. You are also NOT doing the main engine any good running it for brief periods,, It creates excess moisture in the oil,, diesels do not require frequent running..>>>Dan

Motorhome air springs have bump-blocks inside to limit compression and resulting damage.
reference: https://www.firestoneairide.com/content/dam/fsip/pdfs/airmount/EMDG_Imperial_2014.pdf

 

[Utclmjmpr]

My statement still stands..>>>Dan

 

[Gary RV_Wizard]

Motorhome air springs have bump-blocks inside to limit compression and resulting damage.

Yeah, but bump stops are more of an immediate damage prevention. The air bags still get heavily folded when deflated, thus increasing the potential for premature cracking over the years. Using the jacks to relieve compression on the bags seems to me like a good practice even though it's not critical.

 

[Utclmjmpr]

So many folks only keep "toys" a short amount of time and don't really care about longevity,,
I try to keep my playthings for longer periods to maximize value,, as an example my class "A" diesel pusher is in excellent mechanical condition due to attention to the specific needs of my specific coach.. ( I have owned it for 26 years with about 10K per year added and frequent upgrades to stay current) >>>Dan I don't own it to impress anyone,,it is for my personal enjoyment...

 

[Scarypat]

You should also place the jacks in the down position during extended parking,, allowing the suspension to remain in the fully deflated state is very hard on the air bags,, it causes them to remain in a wrinkled position and to crack along those wrinkles... I also have a Mountain Master chassis.. You are also NOT doing the main engine any good running it for brief periods,, It creates excess moisture in the oil,, diesels do not require frequent running..>>>Dan

Although I did test the jacks, I’m not willing to store the mh on them for any extended period of time until I fully inspect those - the previous owner stated that one is « sticky » i.e has difficulty retracting and he used penetrating oil on them all the time - I’m scared he damaged the seals. So far, this poor guy did everything wrong maintaining the machine, except for oil changes that he did at a Cummins service center. He used bleach in the black tank all the time (we know it kills the valves’ seals). He did not put water in the house batteries. Never changed the transmission oil in the 14 years he owned it - I have not seen any receipt that he even changed the filters. Transmission shifts good and this thing only has 60,000 miles on it but never the less…. However, I did pay about $40K for it, which is a fair price for the condition.

Currently I found a parking spot in a truck yard close to home, and the owner allows me to do maintenance in there (the irony is I sold the big house for a smaller one for less yard maintenance, but the old house hada huge driveway big enough for the mh and 3 cars).The weather is too iffy right now to do any work - it’s not paved - gravel - and it does get muddy every time it rains, and it takes a couple of days to dry out properly. Right now, I’m spending most of my time on emptying boxes and doing home improvement stuff on the « new » house, but I’m hitching to spend more time on the MH.

 

[Utclmjmpr]

I can appreciate your trying to "catch up on" the machine,, I've been there.<<<Dan

 

[RayIN]

Yeah, but bump stops are more of an immediate damage prevention. The air bags still get heavily folded when deflated, thus increasing the potential for premature cracking over the years. Using the jacks to relieve compression on the bags seems to me like a good practice even though it's not critical.

Gary, my MH had been stored in a barn for 8 years before I bought it; the same air springs are working great and none have any traces of cracking or dry-rot.