Urgent - Air bags failed to inflate - details - your thoughts

[swduns]

2008 Tiffin Phaeton 40' DP, Freightliner Chassis, 20,000 miles on it
Did Freightliner 100,000 mile service on it, in DEC 2020 even though it only had 9,000 miles on it at the time, have done all regular maintenance, Mar 2022 Bay Diesel in Red bay serviced engine & chassis

Went to leave park this morning (Sunday), headed out of site at 8am, immediately knew something was wrong due to rough suspension, checked and front air bags weren't inflated. loud air hiss from drivers front wheel. Returned to site.

leveled RV (HWH) & connected power then began to investigate. started engine, could hear loud air hiss from drivers wheel, verified front air bags down, couldn't get under rig enough to determine exact source of air hiss.

called freightliner. They provided many local contacts. called local contacts, given its Sunday couldn't get any mobile truck techs and no truck repair or RV repair shops open, made arrangements for 1st thing Monday morning to go to nearby shop (10 miles). without air bags

I guessed it was a dump valve or solenoid seal, possibly hole in air bag.

We went to brunch then returned. I decided to use jacks to raise, then block with cribbing, then find source of hiss. upon cranking .... no hiss ... air bags inflated ... I assume then that it was a stuck dump valve that cleared debris from the HWH leveling dump/cycling several times. I'm guessing.

Ideally I'd like a freightliner dealer to check it out ASAP, ideally a Oasis that we could stay at as we are full time.

Choices:
1) return to travel plans and try to find a freightliner dealer that align with our travels as soon as possible
2) tomorrow drive directly to a freightliner dealer and align travel plans around that
3) use a local RV shop to check it out tomorrow morning
4) Other

I'm sure some of you have had dump value problems and have gained experience. please share any learnings. please share you thoughts as to what i should do next (how urgent is this issue?). Were in VA headed to PA, then Maine. Any freightliner dealers you'd recommend?

Your thoughts?

[Ray,IN]

This may sound silly, but how long ago did you service the air dryer unit? A clogged compressed air filter/desiccant filter can cause unusual problems. Are you using the manual moisture drains on the compressed air tanks or depending on the automatic moisture drains? I use the manual drains at least once a month when using the MH.


From your description it sounds like the front dump valve was stuck open for some reason, but that would affect both front air springs, not just one.
I'm leaning towards a stuck/faulty ride height valve on the port side.

[JNSNWT]

I’d go with #2.
Let the trained specialist work on it.

[swduns]

Originally Posted by Ray,IN

This may sound silly, but how long ago did you service the air dryer unit? A clogged compressed air filter/desiccant filter can cause unusual problems. Are you using the manual moisture drains on the compressed air tanks or depending on the automatic moisture drains? I use the manual drains at least once a month when using the MH.


From your description it sounds like the front dump valve was stuck open for some reason, but that would affect both front air springs, not just one.
I'm leaning towards a stuck/faulty ride height valve on the port side.

My dad was an auto mechanic so I grew up working on cars with him extensively but I know nothing about Diesels. I didn't know that manual drains existed. It appears there are three. I know I have a auto system.

Can you describe the procedure to use the manual drains? beginning of trip or end of trip? how long do you hold them when you pull them? pull and release or pull and hold? hold until air sounds clear? are there any safety concerns? (will air release air bags and fender drop on your arm?), other?

[swduns]

I called Freightliner back last night and discussed the situation.
His advice was. likely a very small particle held dump valve open. said cycling dump valve caused it to clear. said cycle system several times. said if it works normally then continue using coach. again he felt likely a very small particle held drain valve open and said if the particle cleared then the particle isn't there any more. said if it is a bad valve then the problem should reappear with my cycling it. then I should schedule and appointment with a freightliner shop.

[Toribk]

The only advice I can offer after experiencing the same thing a few years back is do not attempt to drive the coach with the air suspension deflated.

It's equivalent to riding a bicycle with the seat missing and two flat tires.....ouch!


It is best to have a mobile truck service come out on site to diagnose and complete the repair.

In my situation, a Firestone rear air-spring failed and the mobile mechanic had it ordered with Fedex overnight delivery and installed it the following afternoon.....in about 30 minutes.

Google "truck repairs near me" or check with the closest TA, Pilot, Flying J or Love's truck stops for a mobile mechanic as most of the tire service mechanics work on the air suspension as well.

I used a local truck repair mobile mechanic in Virginia and the guy was excellent.

[Ray,IN]

Originally Posted by swduns

My dad was an auto mechanic so I grew up working on cars with him extensively but I know nothing about Diesels. I didn't know that manual drains existed. It appears there are three. I know I have a auto system.

Can you describe the procedure to use the manual drains? beginning of trip or end of trip? how long do you hold them when you pull them? pull and release or pull and hold? hold until air sounds clear? are there any safety concerns? (will air release air bags and fender drop on your arm?), other?

Spartan guidance on air system tanks

[oldnavycdr]

Ray, what I find confusing about the Spartan procedure is that it first has you pump the air down to 70# but then you start the engine and run at high idle which causes the pressure to build back up. Any clarity you can offer?

[RoadTrip2084]

Originally Posted by oldnavycdr

Ray, what I find confusing about the Spartan procedure is that it first has you pump the air down to 70# but then you start the engine and run at high idle which causes the pressure to build back up. Any clarity you can offer?

That is correct. They are basically testing that the compressor and pressure cut off valve is working. It should fill from 70# to 125/130# in under 3 minutes or it isn't considered safe to drive from an air brakes perspective.

[69Stang]

My Phaeton did that once and I wasn't in the habit of checking the inflation. Rode like a wagon and I was wondering what was up. I went back into my driveaway and only noticed then that bags weren't inflated. I shut it off and restarted it, and the bags inflated.

You should get in the habit of checking bag inflation. You don't have to climb under and look at at the bags, but look at the space between the tires and the wheel wells. If the rock guard is touching the ground or if I can't put a fist between the front tire and wheel lip, I know they aren't inflated.

[swduns]

I have cycled the air bags/dump many times now with no repeat issue
Wish I had know about this ahead of time to avoid freaking out ...

[Ray,IN]

OldnavyCdr is right. The procedure also tests the one-way valves.