Beware of would-be air suspension mechanics

[Jeff Bayley]

Related to this topic, I was at Prevost NJ for 3 days solid while they tried to track down why by bags were falling and the coach wouldn't stay level. After replacing one part after the other including the Norgren valves there was still no improvement but I got a lot of "Well, those were bad anyhow and also needed to be replaced". On day 3 or 4, I was letting myself into the coach and I heard a hissing noise. I got the so called mechanics attention to it and after further investigation, it was found that the air operated strut that works the recess floor was leaking air and that strut was defective. This was a converter item and Royal had tied it into a part of the air system that was directly tied into letting the air bags leak out and fall.

For what it's worth to the issue of problem solving and wasting money.

[Darl-Wilson]

Jeff, did Prevost adjust your bill or replace the unneeded parts with the originals? If not, did you ask them? I know Jon and several others here would be able to troubleshoot this problem easily. I am curious, did they use a leak detector? What you posted here shows Prevost may be grossly unprofessional. I can't imagine why it would take factory mechanics so long to diagnose this condition.

With 4 bags and 5 valves (I think) how long could it take to detect a leak? Jon just posted that replacing all of these items should be no more than 12 hours. 24 hours and they still didn't find the problem. Something is wrong with this picture.

Please keep us up to date Jeff...and thanks for the post.

Darl

[phorner]

Just to chime in on the subject regarding Prevost service, we stopped at the Prevost Service Center in Jacksonville for a scheduled replacement of the front air bags before leaving for our summer road trip. Since our bus is quickly nearing the 10 year mark, I wanted to start replacing some of the components that typically have a life expectancy of this period. The plan was to do the front bags now and the remainders later. I also had a brake inspection scheduled

The only problem that we ran into was that when the front bags were removed, the technician took note that the brass adapters, that attach between the top of the bag and the air line, appeared to have been cross threaded when they were installed, and his recommendation was that they be replaced. Unfortunately, they were not in stock so we had them shipped over night and installed the next day.

As part of this process, a petcock that is turned off during the removal process was skipped during the final leak test and, since we spent an additional night there, this air leak wasn't discovered until the next AM. This resulted in another trip to the lift where the problem was quickly identified and the petcock replaced at no charge.

The total labor and parts for this project was at the outer limit of Jon's estimate, but still within it, so I don't feel as if I were unfairly charged.

My over-all experience there was excellent. They did find a couple of things that I was unaware of during their inspection and those corrections were made. Our technician worked diligently on our bus, took the time to answer my questions, and made a sincere effort to make sure that I had a clear understanding of what was being done and why.

Based on my one-and-only experience there, I would recommend it.

Unfortunately, the technician that worked on our bus was working his last week there, as he was moving to Kansas City. To his credit, not many employees on their last days on the job would take the time and make the effort that he did to make certain that our repairs were completed not only to my satisfaction.... but to his.

During the brake inspection, he noticed a slight leak at the driver side tag axle hub seal. Well, the seal had so little oil left that he recommended replacing the bearings as well as the seal. With the new seal in place, he must have adjusted that seal a dozen times, to make sure that it was neither too loose nor too tight. I believe he said the tolerance was 1/1000".

And he did this outside in the rain, as someone else wanted to use the lift for another customer.

[Jon Wehrenberg]

Jeff et al,

I want to correct something Jeff mentioned. I do not disagree that the air cylinder for the floor slide when leaking would deplete the auxiliary air system.

However, and this is important for all to understand....with the exception of early vintage coaches (I think the key is four solenoid valves in the steer compartment and not 5 as we now commonly find) the aux air system pressure can go to zero pounds and the bus WILL NOT LOSE AIR PRESSURE IN THE AIR BAGS. This is important to understand because when someone that does not understand the suspension system screws around for several days trying to trouble shoot the system they have to justify wasting thousands of your dollars.

If your bus leans or settles down in the front the cause of that problem is isolated to the related air bags, the fittings on the air bags or Norgren valves, or the five port or three port Norgrens for that particular part of the system.

No other leak anywhere in the bus affects the suspension. Jeff got lied to to cover up an inept mechanic's inability to focus on the only parts that could have been part of the problem. Harsh words, but if anyone wants to verify it access Hector's system power point program and you will see what I am saying. Just bear in mind his system is generic and individual coaches will have minor variations.

[tdelorme]

Jon's information is correct. I had the step slide air cylinder go bad on the Liberty and it had no effect at all on the air bags. I would loose aux. air pressure in a matter of minutes but the coach stayed level. Liberty installed a needle valve on the air line to the cylinder when the coach was built, so I just closed the valve until I got the new cylinder installed.