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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: Dbraskett on March 03, 2021, 11:17:14 pm

Title: 99 U320 won’t air up right front
Post by: Dbraskett on March 03, 2021, 11:17:14 pm
Started my coach today, as a shut it off there was a loud pop and the right front dropped, and now I can hear air leaking under the front. Bags all seem ok, from what I can see without being able to get under it is one of the solenoids on the 6 pack is loose from the metal block. I can push on it with a rod from the wheel well and make the tone of the air leak change. Anyone had that issue before? I need to figure out a way to get the corner aired up to safely get at the valves.
Title: Re: 99 U320 won’t air up right front
Post by: Chuck & Jeannie on March 03, 2021, 11:29:24 pm
Been around here for a while, and this is a new one on me.  Sounds like a rare structural failure where the actual threaded portion of the valve let go allowing it to partially separate from the manifold.  Could have been caused by over torquing the valve when it was installed.

I'm trying to think of a alternate way to rise the right front so you can insert your safety stands and work on the 6-pack...

I don't suppose you have access to a suitable sized air/hydraulic jack that could lift the right corner?
Title: Re: 99 U320 won’t air up right front
Post by: hdff on March 03, 2021, 11:32:01 pm
Try getting a 2x12 and cut it to stack the pieces and drive up on them.  4 pieces would give you about 8". My guess on the 6 pack it you blew out an o-ring.



Keith
Title: Re: 99 U320 won’t air up right front
Post by: Dbraskett on March 03, 2021, 11:41:05 pm
I have a diesel repair shop, and have all sorts of jacks there, but of course the coach is in my driveway at home. I think I'm going to make me an airline to tie the 2 right side bags together and air up with an air hose. All the other bags function as they should
Title: Re: 99 U320 won’t air up right front
Post by: Chuck & Jeannie on March 03, 2021, 11:43:01 pm
With the right selection of fittings and some 3/8" DOT plastic air line tubing, it might be possible to rig up a temporary way to pressure up the right front airbags with a portable air compressor.  I don't know how much access you have to the air line connections on the top of the front air bags on a U320, so not sure if this is possible.

Edit:  I see (above) you have the same idea.
Title: Re: 99 U320 won’t air up right front
Post by: Chuck & Jeannie on March 03, 2021, 11:48:41 pm
Let us know if that idea works, and what you find when you get a look at the 6-pack.
Title: Re: 99 U320 won’t air up right front
Post by: Dbraskett on March 03, 2021, 11:59:52 pm
I'll report back tomorrow afternoon what I find. Scheduled for a Florida trip leaving on the 10th so I hope it's nothing major. Is there a way to bypass the 6 pack and just run the coach with the suspension leveling valves? I'll be parked on flat ground the whole trip, I can do without leveling once I get there if parts availability is an issue
Title: Re: 99 U320 won’t air up right front
Post by: Chuck & Jeannie on March 04, 2021, 12:14:57 am
Is there a way to bypass the 6 pack and just run the coach with the suspension leveling valves?
Yes - looking at my air system schematic, I think it would be possible to do that.  The HWH leveling system is basically doing nothing when the coach is in travel mode.  Air pressure goes to the front height control valve, and from there it is routed straight through the 6-pack manifold via the travel valves, then on to the air bags in each front corner.

Theoretically, you could connect the air lines from the front height control valve directly to the air bags with a dual "Y" tubing setup.

I'm sure other members will chime in on this subject and tell me I'm overlooking some critical detail.



Title: Re: 99 U320 won’t air up right front
Post by: Michelle on March 04, 2021, 08:31:26 am
Started my coach today, as a shut it off there was a loud pop and the right front dropped, and now I can hear air leaking under the front. Bags all seem ok, from what I can see without being able to get under it is one of the solenoids on the 6 pack is loose from the metal block. I can push on it with a rod from the wheel well and make the tone of the air leak change. Anyone had that issue before? I need to figure out a way to get the corner aired up to safely get at the valves.

Just to verify - it's obviously one of the solenoids at the manifold block and not the mini regulator that hangs near the front axle and has a dial gauge on it, correct?
Title: Re: 99 U320 won’t air up right front
Post by: Rudy on March 04, 2021, 08:40:48 am
D,
Purchase two 10 foot 2x12s.  Have each one cut at 4 feet, at 3 feet and 2 feet.  Place the two 4 foot sections in front of each steer tire.  Then the 3 foot sections on the top of the 4 footer even with the end away from the tire.  Follow that with the 2 foot sections and finally the 1 foot sections.  Pull the coach forward slowly till the steer tires are on the 1 foot sections.  Block the drive tires to prevent any rolling forward.  You will have pleanty of room to get under the front and all will be safe.
Title: Re: 99 U320 won’t air up right front
Post by: Dbraskett on March 05, 2021, 05:14:59 pm
Got the coach aired up with a fitting I made for the right side air bag, and the top right solenoid on the 6 pack was blown out of the manifold. Threads in the manifold itself look to be ok, but the solenoid threads look to be messed up. Also looks like this solenoid has been replaced before, it doesn't match the other 5.
Title: Re: 99 U320 won’t air up right front
Post by: craneman on March 05, 2021, 05:28:22 pm
I am surprised that the aluminum threads in the manifold are still good. They are softer than the brass on the solenoid. 
Title: Re: 99 U320 won’t air up right front
Post by: Dbraskett on March 05, 2021, 05:32:23 pm
I am surprised that the aluminum threads in the manifold are still good. They are softer than the brass on the solenoid.

I'm surprised as well. I'm happy about it though. Should be able to replace the solenoid if I can get one quick enough.
Title: Re: 99 U320 won’t air up right front
Post by: Chuck & Jeannie on March 05, 2021, 05:36:58 pm
...the solenoid threads look to be messed up. Also looks like this solenoid has been replaced before, it doesn't match the other 5.
I wonder if that was a previously used (junkyard) solenoid?  Perhaps the threads were already damaged when it was installed on your coach.
Title: Re: 99 U320 won’t air up right front
Post by: Dbraskett on March 05, 2021, 05:39:05 pm
Best photo I can get underneath the coach, but the threads look just fine in the manifold
Title: Re: 99 U320 won’t air up right front
Post by: master2301 on March 05, 2021, 08:51:27 pm
A thought would be to find a threaded fastener with size and thread pitch of solenoid, screw into manifold block and wiggle it to see how much (if any) play there is in threads.
Title: Re: 99 U320 won’t air up right front
Post by: Dbraskett on March 08, 2021, 02:00:36 pm
To update this, got the new solenoid this morning. Threads definitely look better than the old one. Screwed it to the manifold and now the coach airs up properly. The right front won't dump now from the control panel, checked all the coils with a multimeter, and cleaned out the exhaust ports, but that's a problem for another day.
Title: Re: 99 U320 won’t air up right front
Post by: craneman on March 08, 2021, 02:48:01 pm
Don't let the coach twist as it can damage the windshield. You need the right front to dump when the left one does.
Title: Re: 99 U320 won’t air up right front
Post by: Dbraskett on March 08, 2021, 04:31:16 pm
Don't let the coach twist as it can damage the windshield. You need the right front to dump when the left one does.

It levels in travel mode just fine. I'll keep an eye on it this trip, and try to troubleshoot while I'm parked next week. I've seen people pop windshields out twisting a coach, for sure don't need those headaches