The Leans

[Jerry Winchester]

Well I fixed one major air leak and when I returned after a week, my coach is leaning to starboard :confused:

It has plenty of air in the main tanks and the aux air compressor is running and aired up, so I guess the system won't level itself unless the key is turned on?

I am going to get a stethescope with the long snout to do some serious listening, but it may take a goodly amount of soapy water to track this deal down.

We need a trouble shooting decision tree especially for "The Leans".

Jeff, Jon, anyone?

[Jon Wehrenberg]

Jerry,

There is no easy solution to the leans and there is no general path to follow because each converter has their own way of handling the leveling system layout. They are all complex so you can expect to have trouble isolating the specific problem or problems.

I can give you some advice on how to spend a couple of days if you want to cure it for the long term.

Rule out the obvious such as an air bag leak or a leak you can detect with soapy water. Usually however, if a fitting or hose has not leaked before it will not leak now unless it has been disturbed, but checking this is easy so it might as well be done to rule out that as a problem.

Assuming the air bags check OK (corrosion around the bottom of the cans is a likely spot) then you are down to checking the Prevost valve pack up front and the Norgren valves located just about everywhere. Some are Prevost installed and some are converter installed. Look in front of the fender liners ahead of the drive axle, up on the sides and ceiling in the area around the drive and tag axles, in the lower front compartment near the back wall ahead of the steer wheel, and possibly other spots depending on the converter. Some of these Norgren valves have an exhaust, and some do not. Make sure you check for air coming from the exhaust and around the end caps of the valves.

By now you will be dirty, starting to go crazy, and frustrated. But patience pays because sometimes the leak is going to show up. On my 87 a leak in either the Prevost valve pack (which can be rebuilt using a Prevost drop in kit) or one of the Norgrens in front actually was the cause of a leak in my rear air bags on the driver's side.

Norgrens can be rebuilt. If you can find a Norgren distributor near you you can buy the internal spools with the O rings all lubed up and ready to replace the old spool. If you do your own work this is the way I recommend you go.

I built a tester with a few hoses and fitting I got from Lowes or Home Depot so I could apply air to the actuator side (some have a single actuator with a spring return, some have dual air actuators) and air to the supply side to check for leaks. Usually taking off four or five hoses and four bolts removes the valve for testing and rebuilding.

The work is tedious but not particularly hard, but when you are done you may not know which valve repair fixed the problem, but in the end it will get fixed. Or you can spend major dollars for on the job training for a technician. I think Jeff has mentioned that.

You should be aware that you actually have two systems for the coach air suspension with the second being the ride height valves which are in control when the selctor is in the "road" position. These are located in front of the wheel well liner ahead of the drive axle and in the top center between the steer wheels. They have a tube about 8 inches long to exhaust air and if they leak it should show up there.

[Jon Wehrenberg]

Jerry,

Your question about self leveling should be answered because I realized it may have broad general interest.

Some folks park their coach and can leave the switch in the "automatic" levelling position. As the coach leans out of level it will automatically add air to the low side. But this is not possible on all coaches and there may be reasons why this might not work on all coaches.

My 87 front end could not be raised with the pressure my aux air system produced. It topped out at 100 lbs and the front required around 110 to lift it. If the leveling only required side to side air then it was sufficient. But my system would work with the key off. By contrast, my 97 (both Libertys) levelling system will only work with the key on so I no longer have the option of automatically compensating for the leans.

You have to determine on your conversion if the system will work key off and if so will the aux air deliver enough pressure to raise either side or the fron only?

Using the aux air to keep the coach levelled only tends to mask or delay a needed repair. You can defer the repair for a while, but as the leaks get more serious you will lay awake at night listening to your compressor kick on and off and your rear suspension creak and groan as the bus wobbles from side to side. No need to ask me how I know.

Mango might jump in here because he recently tackled a few problems with the leans and I think he fixed them.

Jon

Good flying Thursday. Heavy snow in JHW. Good day to get current.

[MangoMike]

Hey Blowout boy,

Unfortunately my problems are back, and I'm not sure if cold weather is part of the issue as everything seems to be ok when it warms up a bit. My guess, in my case, there's not leak, but a sticky valve somewhere.

Back in September I could hear leaking back by the drivewheels and with my trusty soapy bottle found the left Norgren leaking air. I tried the Jon approach and purchased a rebuilding kit, but it didn't seem to solve my problem so I gave up and just replaced the 3 way, 5 port valve with a new (Norgren) one from Prevost Parts (Penn Air in York, Pa 717.840.8100,Dave in parts have the rebuilding kits #54237-65 & 54237-62).

This solved my problem for a while. Then the rear sagging started again and I found the right one leaking at the same place, replaced that and no rear sagging for about 2 days then more leaking. I need to get under the coach again and start searching but I think there's a valve somewhere that feeds those drive wheel valves and something is sticking open, because the rear comes down within 20 minutes. As I get more confident maybe I'll go back to trying to rebuild, but to eliminate that potential part of the problem I'm just buying new valves (Jon will chastize me for this). I'm working forward and will keep you posted. I'm on a mission.

Mike

[Jon Wehrenberg]

The money he save having me do his maintenance work allows Mike to pay big bucks for a whole new valve.

I can see it now. At the POG rally the only thing we will see of folks is their feet sticking out from under their coaches.:D

[MangoMike]

"I can see it now. At the POG rally the only thing we will see of folks is their feet sticking out from under their coaches"

Hopefully with toes up.

Mike

[lewpopp]

that was such a good reply, you had to "burp" it up twice.:D :D

[Jerry Winchester]

Mike;

I thought you had been in hiding from the V-Tail assult.

From Jon's tome and your notes, I can assume this is not an easy problem to fix, but I am looking in my pile-o-stuff that came with the coach for a schematic that details the system.

To appease my sense of symetry, I lowered the whole coach to the point where it won't sag any more; that way I am not possessed to go start the engine and go thru the process of having it level itself out everytime I walk in the hanger :(

[MangoMike]

I have Mango's camouflaged from the air so we feel relatively safe from the V-tails, it's those 210's I worry about.

I can't remember if you have a Liberty, but if you find any schematics on the bag system it would be great to share. I did call Liberty once and talked w/ someone who says they don't keep any on record. I guess they just wing it during construction.

I'm going to try to document the ones I find on my bus.

The anal in me put 4 laser levels on 'L' brackets on the wall facing the four corners of the bus so that I can tell if the bus even drops a mm.

Mike

[MangoMike]

That was such a good reply, you had to "burp" it up twice.

Some of Lewpopp's coloqualisms have me scratchin' my head.

[Jon Wehrenberg]

Jerry,

If you are blessed with the ability to decipher a pneumatic system diagram such that you can isolate the source or sources of the leak that makes your coach lean we are going to nominate you the POG vice president in charge of the leans.

On my 87 I had the Prevost portion, but lacked the full system diagrams because Liberty added their portion. Despite my best efforts I never could conjure up any reasonable semblance of logic to how the whole thing worked. I felt fairly inadequate until I watched the Prevost techs at the factory attempt to isolate a problem. They did the soapy water squirt bottle thing.

Over the years I watched the techs at the NJ and FL service centers do the same thing at about $80 an hour.

Without a pit (which was my circumstance when I tackled my 87 coach leans) I found I could take the valves from the bus and test them, fix if required, and replace them almost as quick as the method the techs use. Most of the valves do not have to be removed to have the spool replaced.

Before you go crazy looking for valves verify it is not an air bag. Before corrosion of the bottom "can" shows up as a leak you can hear, there will be microscopic pin holes that will allow air to escape one bubble at a time. All of the bags on one side in the rear are tied together so a leak in any one lets them all sag. It is very difficult to get the soapy water spread all around the bottom of the air bag and its support surface so a leak will blow visible bubbles, but that is how you have to do it. It is made more complex by the fact that the height of the air bag may affect how it seals at the bottom, so if your leans are intermittent and you see a pattern of leans based on how much or little the air bag is extended that might be a clue it is a bag.

If you start tackling this problem now, you will be ready for the rubber room by the time you get to the rally.:)

[Jerry Winchester]

I may be ready for the rubber room just talking about it.

But I have not reached Mike's level of anality such that I have the laser levels out in force and taking measurements with a micrometer.

Airplanes are somewhat easier but much less forgiving. If you drop a screw in an unretrievable place, just change the empty weight of the plane............

[Jon Wehrenberg]

Planes are almost equally frustrating.

Several months back I had my alternator drop off line. No CB popped, but it would just drop out and I would not be charging.

If I cycled the alternator side of the master it would come back on. Maybe for the rest of the flight, maybe for 10 minutes. Since I routinely fly to JHW and an approach to minimums is not uncommon during snow squalls I decided not to let the mechanics play "try this".

I had everything changed, including the master switch, alternator control unit, alternator and the over voltage relay.

After about two flights guess what? The CB for the alternator control unit (voltage regulator for you bus guys) started to pop out. That turned out to just be a lazy CB and since that was changed I think my little electrons are all running around the way they are supposed to.

Now my turbo is bootstrapping and tomorrow I am going to massage the wastegate with a little mouse milk (no joke bus guys) and see if that fixes it.

Anybody want to trade a nearly new bus for a 97 bus and a great P210?

[Jerry Winchester]

Mouse Milk is a sure lube-er-up-er for something stuck.

Since my plane has fewer moving parts than yours, it would stand to reason that yours would promote entry to said rubber room sooner.

But you must have some serious amp draw at times. I think the only time my alternator is taxed is when the gear is being cycled. I changed out the landing light and installed one of those "Boom Beam" lights from LoPresti, so I went from 70,000 candlepower, to about 500,000 with half the amperage and no filement to break.

I really just wanted the tower guys at DWH to mistake me for a jet on approach..........

[Jon Wehrenberg]

Big current draws:

Gear
Windshield de-ice
Prop de-ice
Pitot (which includes stall warning)
Headlights

Nothing really big, but lots of little things. About 40 or more circuits. 95 amp alternator and 7 amp standby generator for emergency use.

So far seven electrical system failures over 20 years from things like alternator and alternator control failures to broken field wire, failed alternator CB, broken belt, etc.

In 16 years of driving bus three alternator failures and one failed field wire. I guess if it is mechanical it will break.