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Topic: Exploding Dash (Read 595 times) previous topic - next topic

Exploding Dash

Well, luckily we were only leaving Costco a few miles from home when a mighty blast of air blew our dash apart tonight.    We are preparing to head west tomorrow, so pretty lucky that it happened tonight.  Scared my son and I as if a tire had blown. 

Turns out it was what I believe to be maybe the air horn solenoid behind dash. Nylon or plastic air line had completely blown out of compression fitting and the front air tank dropped to 30 psi in roughly 30 seconds.  Anyone experience this worrisome event before???

Muri: 2003 U295 3620

Re: Exploding Dash

Reply #1 –
Quote from: TLandon –
...the front air tank dropped to 30 psi in roughly 30 seconds.
Sorry you and son had to experience this unsettling event.  If it happened to me, I'd probably have to stop and change my underwear.

Please assure your family that this is not a common event - and travel in your coach will normally be much less traumatic.

Your front air tank pressure dropping to 30 psi indicates a malfunction of the protection valve on that tank.  You should, at your first opportunity, either replace that component or else take it apart and clean it out.  The purpose of this safety valve is to maintain a minimum amount of pressure (approximately 60-65 psi) in your brake system tank, when there is a sudden loss of pressure in some auxiliary device (like the air horn solenoid).  This retained pressure reserve allows you to stop the coach safely, and then deal with the air loss problem.

Since your coach is newer than mine, your air system will be laid out differently, but the protection valve should still be mounted directly on the front air tank.  It might look similar to the photos in the link below below, or it may be a more modern design.  Find it - fix it!

Part Number Collection
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Surely, no age has been more fraught with insecurity than our own present time."

Re: Exploding Dash

Reply #2 –
Thinking about your "incident"...  If the compression fitting on the air horn solenoid was done up correctly, there is no way that hose could "blow out".  Did you look at the end of the tube, before you put it back in place?  There should be a small brass reinforcing tube installed in the end of the plastic air hose.  This brass tube gives the compression ring something to "grab".  Without it, the "blow out" you experienced would certainly be possible.  See example of a brass support tube in photo below:
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Surely, no age has been more fraught with insecurity than our own present time."

Re: Exploding Dash

Reply #3 –
Yes, the brass insert was still in the failed fitting.  The fitting was not a screw on compression type, but rather a brass and plastic push to connect fitting similar to picture below.  The black plastic "piece" on the end had blown out and was "pushed" up the nylon line. 

I have temporarily placed a new fitting that has a pipe thread on the solenoid side and a barb fitting with hose clamp on the nylon line.  Hope this holds for a while!

Thank you for the advice on the safety/check valve on tank.  I will check that out. 


Muri: 2003 U295 3620

Re: Exploding Dash

Reply #4 –
The "push on" style is a good one and widely used.  Wonder if the hose was not inserted far enough in the fitting???
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020
 

Re: Exploding Dash

Reply #5 –
I just had the same thing happen on our 03 about a month ago, think it was caused by to much tension on the fitting as it was installed . I replaced the fitting with the one that has the ferrule and nut and also cut the wire ties and rearranged the solenoid, my wife had been telling me for months that she was hearing a small air leak in that area, but I could not hear it until it blew and then I could hear it and find the leak
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins