Frank McElroy Posted November 3, 2022 Share Posted November 3, 2022 Since your test made sure that the internal check valve is good, let's do one more test. Dump the rear dry tank air. Then see is you still hear the squealing. If you still do, the parking brake release manifold valve is good. If the squealing goes away the parking brake manifold valve is your problem. Link to comment Share on other sites More sharing options...
ziaptrn Posted November 3, 2022 Author Share Posted November 3, 2022 (edited) Follow-up for the Follow-up 🙂 Filled all air tanks and set to Travel Mode. Drained rear dry air tank and then tested leveling. Same squeal remains on re-inflate in the front; no change. Re-filled all and re-leveled. This dismisses the parking brake release manifold valve as being the source. The results apparently leave the second remaining front tank pressure protection valve (first one replaced previously) as the most likely culprit to date. The replacement is on order, and I'll install upon arrival as well as report back - hopefully reporting "The Sound of Silence." John Edited November 3, 2022 by ziaptrn to correct spelling error Link to comment Share on other sites More sharing options...
96 EVO Posted November 3, 2022 Share Posted November 3, 2022 I thought the suspension got it's air from the secondary tank? Link to comment Share on other sites More sharing options...
ziaptrn Posted November 3, 2022 Author Share Posted November 3, 2022 Yes - but the 'test' was for the parking brake release valve, not the rear suspension and airbags. The rear airbags have been blessedly silent all along. Unless I'm incorrect, and the parking brake release valve is connected to the suspension? The 1/4 inch air drain in the rear is for the suspension, and the 3/8 inch drain in the rear is for the brakes, as I understand it. That said - the libraries are full of things that I don't know! I may easily be wrong. I suppose I could always try with the rear suspension also deflated. This has to be one of the easiests tests that I've ever done! John Link to comment Share on other sites More sharing options...
96 EVO Posted November 3, 2022 Share Posted November 3, 2022 (edited) I'm sure Frank has the air system schematic for your coach, but I always thought 'all' airbags were supplied from the secondary tank. The secondary is the larger dry tank on these coaches. Could be wrong but I've always thought it supplied all the bags. Edited November 3, 2022 by 96 EVO Link to comment Share on other sites More sharing options...
Frank McElroy Posted November 3, 2022 Share Posted November 3, 2022 The parking brake release valve on the front secondary tank gets air feed from either the front secondary or rear primary air tank. This valve also serves to equalize air pressure in both tanks. When airing up the front suspension, the front secondary air tank will drop in pressure and air will flow from the rear primary tank through this valve to the front secondary air tank. That's why I wanted to have a test done with the rear dry air tank emptied. The parking brake will release using air from either the primary or secondary are tank as long as one of the tanks is above minimal air pressure to release the parking brakes. In a case where you lose air pressure in the main rear air tank, when you step on the brakes, air from the front secondary air tank will stop the steer axle and modulate air in the parking brake air circuit to give you drive axle brakes in order to safely have about 5 brake applications from air in the secondary tank before the drive axle brakes lock up. 1 Link to comment Share on other sites More sharing options...
ziaptrn Posted November 9, 2022 Author Share Posted November 9, 2022 Following up.... Replaced 2nd Pressure Protection Valve and associated fittings. Sound/squeal persists. Everything I do seems to make it a tiny bit better (softer) but still....something is making the 'harmonica' sound when the air bags fill after pressing Travel Mode. Adjustments with manual mode do not cause the squeal, nor does air releasing from the air bags when leveling. We are in FL so have been a little busy watching weather, etc. but looks like everything will be ok where we are in Wildwood. I'll update ongoing as I have time to continue fiddling and listening, etc. I'm trying not to simply throw parts at it, but all tests come back as 'ok' individually. Other than Josam's in Orlando....anyone know of a place that would be interested in having a look in Florida? We will be heading back up to the panhandle next week. Thanks again for everyone's support and assistance to date. I'm learning a lot! John Link to comment Share on other sites More sharing options...
Ivan K Posted November 9, 2022 Share Posted November 9, 2022 I think you narrowed it down to the top sixpack valves and the ride height valve since everything else is shared with raise/lower actions and not causing the sound. Link to comment Share on other sites More sharing options...
ziaptrn Posted November 9, 2022 Author Share Posted November 9, 2022 And the ride height valve also is newly-replaced. When you say six-pack, do you mean the manifold from Valid? (the one with the solenoids, etc). I removed it, cleaned it, and lubed and replaced all of the o-rings as a first shot at the anti-squeal endeavor. It was squealing before I worked on the manifold, and still does now...so it didn't change anything for the worse. There is always the possibility of a bad 'new' part.... John Quote Quote Link to comment Share on other sites More sharing options...
Bill R Posted November 9, 2022 Share Posted November 9, 2022 1 hour ago, ziaptrn said: I'll update ongoing as I have time to continue fiddling and listening, etc. I'm trying not to simply throw parts at it, but all tests come back as 'ok' individually. John - this may have been mentioned prior, but I think you may be at the point where if you are still going to troubleshoot this yourself you may consider getting a few inline valves and start isolating the system components. Using your air diagrams you should be able to start to narrow down section by section where the squeal is or is not coming from. Of course if there is more than one cause, it will become more difficult but doable. All the best. Link to comment Share on other sites More sharing options...
Ivan K Posted November 9, 2022 Share Posted November 9, 2022 Looks like you already covered what I would have suspected first. Not sure how is Valid different from our HWH but since it only happens with ride height, I could disable one ride height valve at a time and with a little bump on the ride button see if it happens with one side only and go from there. Link to comment Share on other sites More sharing options...
Solution ziaptrn Posted March 31, 2023 Author Solution Share Posted March 31, 2023 A final follow-up on the Squealing situation. It took me a matter of months (since last November, to be exact), but today, the problem was solved. After changing all of the leveling and air components that I could, the squeal persisted. No 90 degree turns in lines, I increased the line size to 3/8" on many of the 1/4" lines, I replaced pressure-protection valves and even the solid connections like elbows, etc. all to no avail. Every bump in road/dip/shift gave a small 'squeal', and a long-continuous squeal on moving air bags to travel mode as previously described. I elected to change the shock absorbers earlier this year, and when the new shocks finally arrived, I elected to have some assistance(!) with the task and hired a friend of my brother who does some coach work for him to help. He is the nicest young man and at least 30 years my junior, which gives him an edge with mobility and strength both. I'm just not as young or as strong as I wish, and 10 shock absorbers was a large task. While underneath the rig, I asked the mechanic/assistant what he thought about the squeal, and we played "make the rig squeal" for at least 30 minutes trying to isolate the problem. His hearing was spot-on, and he immediately said "that's a stuck solenoid somewhere." The squealing sound resonated throughout the entire front tank and air system, and I just couldn't tell where it was coming from. We finally settled on the likely culprit being the Right Front ABS Modulator Valve - Bendix M32 version. While I was up top making the rig squeal, the assistant said that he could feel the left front modulator moving/vibrating, but the front right could not/did not. Closer visual showed that the small rubber gasket designed to keep water out of the valve was missing also. AHA! Long story short - I replaced the right front ABS Modulator Valve this morning with a new one from Northwest RV Supply in Eugene, OR because they have a lot of old stock Monaco parts from back in the day. Perfect fit, and now....Blessed Silence. I am posting to give final follow-up; we ended up moving from New Mexico to Alabama after the first of the year, and that I just didn't have time to work as much on the rig until recently. Thanks again to all who stepped up. Even knowing what is NOT causing a problem does 2 things for me - it not only helps to solve the issue at hand, but I also walk away with improved understanding of an increasing number of systems. Best wishes to all and safe travels .... John 1 Link to comment Share on other sites More sharing options...
Old Dog Posted March 31, 2023 Share Posted March 31, 2023 If I'm reading this correctly, the issue was with the air brake system (ABS Modulator Valve) and not the Valid Air Leveling System. Just trying to clarify for my future reference. Thx Link to comment Share on other sites More sharing options...
ziaptrn Posted March 31, 2023 Author Share Posted March 31, 2023 Yes, precisely. Not the leveling system (as initially suspected). The air brake system - regular drive - and not the air bags or Valid system. Apologies if I didn't make that clear! John Link to comment Share on other sites More sharing options...
ljandl Posted October 28, 2023 Share Posted October 28, 2023 New to me 2007 HR Imperial 42PBQ, coach worked great for first two trips, on the way home from storage (for my third) I noticed that the ride height control valve was leaking. Couldn't find exact replacement but one that would work. as i was installing the chassis control link, every time the valve required air the system would squeal. Coach was park in driveway, ignition off, and air system pressurized. Squeal is not coming from RHC valve. As i was leaving in a few hours didn't have time for further testing. Valve worked and keeped the suspension at ride height, but squealed every time valve required air. Will replacing with correct valve cure the problem? Could not find PN on old valve. Do I need to go through the above tests to check all other connect systems? Thanks Leland Link to comment Share on other sites More sharing options...
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