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Author Topic: MC5A settling too fast......  (Read 4642 times)
NCbob
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« on: January 27, 2007, 05:39:32 AM »

I ran this problem past Jack Conrad earlier this week and he suspects my left rear leveling valve....but I'm ahead of myself.

My problem is that my bus settles all the way down, now, overnight.  So much so that the hose adapter from the black water tank is pressed hard against the ground...and it's a short 45 deg...not a 90.

The bus settled over time in the past but it's only the left side that drops drastically.  The other day when I aired up the bus I shut it off at 125#'s and went out to disconnect the batteries.  When I re-entered the bus I looked at the air pressure guage and it had already dropped 10 #'s.  I hear no leaks but that doesn't mean much since my hearing isn't that good anymore.

I'm in central FL where there are no bus shops with pits and it concerns me to think about taking it to NC to my regular repair shop for fear of having a problem on the road with the air system. I don't suspect it being an air bag or beam...last inspection showed both the beams and the bags in good shape.

Any ideas as to the cause or a possible repair shop in Central FL?

NCbob
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« Reply #1 on: January 27, 2007, 06:21:42 AM »

The obvious answer is that you have an air leak. The leveling valve is a good possibility.  If it is bad, it can bleed air from the bags and from the sytem, as the system tries to keep up with the leak.  If it is good, then you have a leak in the bags or beam.  For a  simple test of the leveling valve, put the small exhaust tube hanging down from the valve into a cup of water and if it is leaking  you will have lots of bubbles.
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« Reply #2 on: January 27, 2007, 08:09:02 AM »

Running a tube in a cup of water is a great trick, as My hearing is one ao several things to go.
I have sorted out leaks by airing up the bus with an air compressor, not the bus engine mounted cmpressor. This will keep pressure on without the engine idling away.

Good Luck,
 My leaks were mostly accessories previous owner installed, I.E. baggage door locks and associated tubing.
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« Reply #3 on: January 27, 2007, 04:41:44 PM »

 Bob there was a bus repair place passing out cards at the rally in Arcadia. They were in Lakeland, I think. I have no experience with them. I used a squit gun with bubble soap (the kind kids use for bubbles) may or may not find something for you. If not it will help you enjoy your second childhood Grin
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« Reply #4 on: January 28, 2007, 06:49:52 AM »

I bought an ultrasonic leak detector - its amazing.  If you can find someone who owns one (or better still - use this as an excuse to add to your cool tool quotient) you will be able to find your leak.  Guaranteed.

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« Reply #5 on: January 28, 2007, 08:15:58 AM »

Bob,

Wish I was still down there, I'd help you find and fix it.

Jack had one of those ultrasonic detectors, but I didn't get to see how well it worked. He spoke highly of it, though.

I would suggest blocking the coach, removing the rear duals on that side, and spraying everything with soapy water. I had a cracked and leaking bag on the first bus I bought that I could not hear, but it was enough to keep that side from airing up. Also check the air hoses along their entire length. I've seen them leak through the braiding in the middle of the hose. Look good on the outside, cracked inside.

It certainly could be the leveling valve, but I'd be spraying everything in there with soap.

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« Reply #6 on: January 28, 2007, 08:22:25 AM »

The beauty of the ultrasonic detector is that it only listens for ultrasonic noise (beyond our hearing range) so you can use it in a noisy environment - engine running, shop air running, radio on in the shop, whatever.  I was pretty skeptical prior to using it but it is an amazing tool and it really does work.

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« Reply #7 on: January 28, 2007, 01:58:09 PM »

Bob,

I'm near Fort White, north of Gainesville and have a pit in my shop.  Come on up, we'll see what we can do.  The only problem is parts availability up here.  Nothing but NAPA and Discount.

Len  352-214-6498
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« Reply #8 on: January 28, 2007, 07:05:05 PM »

Sorry to hear of your problem Bob!   Stan has covered how to check the leveling valve and that's what I'd do first.  The vent hoses may be gone...look for a small plastic barb on the leveling valve...push a long hose onto the barb and you don't have to get under the bus beyond attaching the hose to the leveling valve.  You may be able to reach this from in front of the tire...without getting between the bus body and upper tire...not sure about a '5.   My airbags leaked and T hears really good but she couldn't hear anything even in a dead quiet area inside.  An airbag gets a case of the fizzies and air just ooozes out...not a real leak from one hole...which would be audible.   
How old are your airbags?   Are the airbeams plated?   
Anyone got a link or picture of an ultrasound leak detection device?   My bus airbags will stay up for weeks, but nothing else does...gotta get on with the leak fix soon.   Tried to get Jack to do an air leak resolution "seminar".  Even generously offered the free use of my bus for the seminar.... but nope...didn't happen.  Oh well, there's still T'ville....DALLAS..(or should I say CAT!)!  Time to set some dates!  And if you need any ides for seminars....I have a couple.  Grin

Best, JR 



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« Reply #9 on: January 28, 2007, 09:36:18 PM »

NCBOB
I sent you a private message, but thought I would respond on board. While at Arcadia I talked with one of the owners of Central Florida Bus repairs out of Lakeland Florida. they were in the charter business until the insurance hikes after 9-11.

I stopped at his place on the way back to Wisconsin, mainly to get the underside of the bus checked out. It didn't need much, it was mainly for my peice of mind, but they did go out of their way to help and his prices were very fair. And they have some hook ups in their yard too.

Nice people, and I am sure they can find your leaks.

Call;
John Silver 863-665-8155
                863-559-8862
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« Reply #10 on: January 30, 2007, 07:19:19 PM »

Bob,
This reply might be a little late. But on my 5A there is a check valve installed on each leveling valve on the air beam side. It is a $12.00 part. If it goes bad, it lets the pressure from the air beam back through to the leveling valve exhaust and that corner of the coach settles. That is what caused my problem when the right rear corner of the coach started settling overnight. I should be able to find the part number for you if you need it. Its an easy fix though I removed the duals to get at it.
Fred
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« Reply #11 on: January 30, 2007, 07:27:46 PM »

JimC - that's Wynn Silver's son (another Fla busnut with an Eagle) - he used to operate 'Central Bus Huh?' and yes they had a large fleet of charter buses - they are good people and located close to I4 just SE of Lakeland
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« Reply #12 on: January 31, 2007, 05:21:31 AM »

Fred, if you could locate the number on that check valve you talked about I'd sure appreciate it.  I can't see one on my L/R valve which is the only one I can see without crawling under the bus.  Thanks for the comeback.

NCbob
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« Reply #13 on: January 31, 2007, 05:24:07 AM »

Fredward: Are you saying that you have have a check valve on the line to the airbeams that only allows the leveling valve to raise the bus but not to lower it?
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« Reply #14 on: January 31, 2007, 07:11:13 AM »

Bob..you say your hearing is not what it used to be,hows your sniffer,is it up to par....*smiling*....I had an old gentleman tell me that the way he found difficult air leaks was to get some of your wife/girlfriend or what ever purfume,remove the line from your engine compressor and put a few drops in it.Fire that baby up and let your nose lead you to it....Frank
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NCbob
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« Reply #15 on: January 31, 2007, 05:30:46 PM »

Y'know, Fred and Stan...that thought was working through the processes of my Neanderthal brain after I asked Stan for the part number of the check valve.....   but then in checking the Parts manual I discovered that there is a pressure protection valve. Now what that sucker does for or against me I haven't the slightest idea...but was wondering if perhaps that might be the valve which Stan was referring.

It has dawned upon me that no matter what I think...or which path I decide to pursue in the quest for the solution to my current problem (somehow I firmly believe that there will be more on my personal horizon) one of the items I will require in my 'bag of tricks' will be an ultrasonic leak dectector.  I have taken steps to acquire one.  As I was telling Ace the other day...I didn't need a 600# torque wrench until I removed both set of rear duals...then scratched my head and wondered why I hadn't bought one until now.

But, be that as it may, before I go much farther I will have more information than I have at this time and will listen dutifully to any and all offerings.  One of these days, providing I live long enough I,  like Jack Conrad, Fred Hobe, Jerry Liebler and a few others who are pillars of our Bus community, will be able to impart to others the wisdom of my experiences.

So, if you have an offering which might help solve my dilemma...I'll be more than happy to listen.

NCbob
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« Reply #16 on: January 31, 2007, 08:45:36 PM »

Stan/Bob,
The Check Valve I refer to is Mohawk part# 5549539 and it screws right into the leveling valve and the line to the air beam screws into it. My MC5 has one on each leveling valve. I was at C&J Bus here in the Mpls area ready to buy an airbag because I figured that was what was leaking. One of the mechanics there told me to replace this component before replacing the air bag. Low and behold, that corner of the bus quit settling. I don't know how it works Stan, because as you suggested, the leveling valve is bi-directional. But this liittle item did the trick. You can reach C&J Bus if you want to buy one. Otherwise, I'm sure you can get it from MCI. Mohawk is in Niles, IL 60714. C&J's phone number is: 952-881-0034 or 800-228-7349 (i've never tried that number). Ask for Yves or just ask for parts.
Fred
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« Reply #17 on: February 01, 2007, 05:32:13 AM »

Fredward: I had a MC-5A for about ten years and I don't remember seeing a check valve on the bus air beams or on the air line diagram. I thinik that someone put the check valve in the line to solve the problem of a leaking leveling valve. There ia a filter (that looks like a small check valve) in the line that prevents dirt from the inside of the airbeam going back into the leveling valve when it is exhausting air (lowering).

If your bus has a check valve in the air beam line, the leveling valve would add air when additional load was in the bus. Not being able to discharge that air when the load is removed would have your bus looking like a kid's hotrod with a jacked up rearend.
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« Reply #18 on: February 01, 2007, 11:58:29 AM »

Hello everyone,

I'm new to this site and already found it very informative.
Just wanted to introduce myself and say thanks for all the great ideas.
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Scott Russell
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« Reply #19 on: February 01, 2007, 12:34:39 PM »

Hello everyone,

I'm new to this site and already found it very informative.
Just wanted to introduce myself and say thanks for all the great ideas.


Howdy Scott, and welcome aboard. I think you will find it a great bunch of guys and gals.
Richrd
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« Reply #20 on: February 02, 2007, 05:30:18 AM »

Just a bit more information..FWIW.  After talking with Dick Wolfert, Christy and Larrys' saviour during their mishap after Arcadia this year, I put a block under the Left Rear radius rod and waited.   Surprisingly I held air pressure in the system almost all night Normally it leaks down in 30 minutes). While I haven't looked this morning (it's raining quite hard) I'm sure  there's been no appreciative settling.

I will have a definitive answer in about two weeks as I'll be taking the bus over to Dick and we'll chase this gremlin down and fix it once and for all.

Thanks for your input...but stay tuned for the final conclusion.

NCbob
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« Reply #21 on: February 02, 2007, 06:11:02 AM »

NCbob -  We now refer to dick as SUPERMAN - show a little respect - LOL
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« Reply #22 on: February 02, 2007, 12:47:33 PM »

Stan,
You are right about it having a filter in it. And you are also right about it doesn't make any sense for there to be a check valve there (now that i think about it) but oddly enough the mechanic at C&J recommended replacing it first (cause its cheap) and after I replaced it she quit leaking down.........My left side settles faster than the right side so i was going to do the same thing to that side. Now I'm really confused.
Fred
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« Reply #23 on: February 02, 2007, 01:39:37 PM »

Fredward: No need to be confused. Go back to the second post on page one of this thread where I told NCBob how to check for a leaking leveling valve. If a check valve in the beam air line stops the leak, then it pretty much has to be a bad leveling valve.

You can get a kit to rebuild them, but  most people just replace them. The check valve idea is a bandaid solution that may solve one problem but it creates another one (won't level properly). Many, many years of experience on many kinds of vehicles has taught me that it is not necessarily right just because a mechanic did it.
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« Reply #24 on: February 22, 2007, 06:00:27 AM »

Just an update on an old topic...but last Monday I took the bus over to Dick Wolfert and put it up on his ramps.  Using an Ultrasonic Leak Tester I'd bought we quickly found that the Left Rear leveling valve was leaking. I had a spare valve but it turned out to be for the right side.  Fortunately Dick had a new valve for the left side so we compromised and installed both.  What the heck...the bus is almost 39 years old now and who knows how long parts are going to be around?

Sometime during the night everything went to hades and I almost got tossed out of bed. The whole left side of the bus was down!  Hmmmm...back to Dick's on Wednesday and up on the ramps again.  We checked and double checked everything he did and more.  There wasn't an air connection we didn't check with both the tester and soapy water mix!  The only leak we could find was a small inconsequential leak at the R shutterstat cylinder.

Strangely enough...now it seems that the front is settling on the left side overnight.  Please, before I buy a straightjacket, can someone throw some light on my problem?

NCbob
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« Reply #25 on: February 22, 2007, 12:58:00 PM »

NCBOB: First, consider a properly working system:  The term leveling valve is a misnomer in that it determines the height of the body above the axles, not the height above the ground. The single front leveling valve only raises the front of the bus and helps to control the front to rear level. The rear leveling valves can raise the rear of the bus individually and so they determine the side to side level. That is. if you let all the air out of one rear side, the entire bus will lean to that side, even though the front system is working properly,

quote"Sometime during the night everything went to hades and I almost got tossed out of bed. The whole left side of the bus was down!  unquote.

  Do you mean that the left side dropped suddenly? Did both left rear tires suddenly go flat? Did you have a ground subsistance under the left rear wheels? Did your new leveling valve leak and let the bus go down slowly?  I don't know how well your ultrasonic leak detector works, but I am sure you aware that a common place for MCI suspensions to leak is through the top of the air beam under the wooden floor. This thread is so old that I don't remember all the previous posts, but the standard cure for a leaking beam is to put  plates between the air bags and the beams and connect the air line to the plates.

Give us some more information and we will try and help.
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« Reply #26 on: February 22, 2007, 04:45:32 PM »

Seeing as how I added more confusion rather than clearing it up: Brian Diehl was here on Sunday and he knows the check valve I am referring to. But it is ahead of the leveling valve, on the pressure side not between the valve and the air beam. Apparently standard issue on MCIs and prone to failure. Symptom of failure is leaking down. Fix is really simple but I had to remove the outside dual to get at it.
Fred (I was really starting to wonder)
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« Reply #27 on: February 22, 2007, 05:57:05 PM »

Fredward: That checkvalve has a slightly different purpose. Normally, the bus will sit up on bag pressure for weeks or months if there are no leaks and the leveling valve is holding properly. One or two people getting into the bus will not cause the leveling valve to open. It has a fairly wide dead spot at the center position. If the bags leak down (or a large amount of weight is added to the bus) the leveling valve opens to the supply, to add air.

If there is no air pressure in the supply line, the checkvalve you refer to prevents the bags from leaking back into the supply tank. If your suspension and leveling valve are not leaking, this checkvalve will normally not come into play.
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« Reply #28 on: February 22, 2007, 07:13:46 PM »

Bob, do you have airbeams?  I'm not familiar with '5s but, airbeams will leak and you cannot ID the leak.  Often on top of the beams.  Simple fix if this is the problem.  Relatively simple to fix. 
Stan has already described the function of the leveling valves...not much to add there...but if the LH side is dropping, it's due to the LH rear airbags or related components...not the front.  The front may be leaking down too..or they are properly inflated and the LH rear is allowing the bus to tilt. 
The front airbags can tilt to the stops with 60 lbs of air as the front airbags are "T'eed" together. 
Have you considered isolating the drive axle airbags?  Install some valves so that you can turn off the aircharge when the bus is level to the drive axle.  Then, if it leaks...you have your problems isolated.  If it doesn't leak with the valves closed, the leveling valve or check valve is leaking.
You could air it up, shut the valve off, and drive it if necessary.  If it leaks down, open the valve and it'll air up.  And, you'll narrow down your leak.   Old airbags can leak and be difficult to ID...they sorta "seep."
Keep us posted on your progress!
Don't let Jackie fall out of bed!   Wink
JR 


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« Reply #29 on: February 23, 2007, 05:02:50 AM »

Quote
Do you mean that the left side dropped suddenly? Did both left rear tires suddenly go flat? Did you have a ground subsistance under the left rear wheels? Did your new leveling valve leak and let the bus go down slowly?  I don't know how well your ultrasonic leak detector works, but I am sure you aware that a common place for MCI suspensions to leak is through the top of the air beam under the wooden floor. This thread is so old that I don't remember all the previous posts, but the standard cure for a leaking beam is to put  plates between the air bags and the beams and connect the air line to the plates.

No, the left side doesn't settle quickly (like a  blowout) it takes a while...like overnight. And I did NOT take up the floor before building the bedroom...no reason to question the settling thing.  It seems that the bus settles more when we're aboard...that is..just our walking around probably makes the air valves ask for more air and when there isn't any it settles.

I didn't see any check valve when Dick replaced the valves but did note the screen adapter on the air beams. It appears the the line from the wet tank goes to each air valve. Unless the check valve is built into the air valve on the inlet side I have no idea where it might be.

Too, after having been on the road, I believe the bus height above the road is the same on both sides.
There is also a 12.5 KW Kohler genset on the left side of the rear bay...that too probably adds to the left side settling.  That is going to be removed and sold this spring in the hope it will help a bit.

Thanks to all for their input.

NCbob
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« Reply #30 on: February 23, 2007, 08:32:59 AM »

NCBob: You have reached the point where you have to isolate the problem with some serious testing. You have to make up a test fixture (which I have described numerous times before) and test individual sections.  The most obvious first test is the left rear suspension. If that is good, let us know and I will explain how to proceed after that.

BTW: The genset has no influence on the suspension going down. The sole reason for having a leveling valve is to compensate for weight in the coach.

How to make a test fixture:
Get about six feet of 1/4" plastic air line.
On one end put a T with a pressure gauge, a shut off valve, and a coupler to connect to shop air.
On the other end, put a fitting that is easily adaptable to the various sizes and types of air fittings on your bus.

In your case, start with the fitting similar to the fitting on the air beam or just a pipe thread fitting to screw directly into the air beam. Connect your test fixture to the air beam. pressure it up to about 60 PSI, close the shut off valve and wait.  If you still have 60 PSI the next day, it is likely good and you can proceed to the next section. If you don't have 60 PSI, you have a leak in the suspension somewhere.  Now is the time for the squirt bottle with bubble soap, ultrasonic detectors or anything else you can find to detect leaks in a 60 PSI system.  Start with your test fixture and test every joint and every square inch of the system under pressure that you can get to. If you find no leaks, but know that it is leaking, then it is probably leaking in the top of the air beam. At that point you have to decide if you eant to repair it or if you want to put in the adaptor plates that seal of the beam from the bags.

Take all the necessary safety precautions before going under you bus and good luck.
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« Reply #31 on: February 23, 2007, 08:47:11 AM »

OK, I know that this is not the answer to your question.  Well, not a direct answer anyway.

I also have a 5A that settles overnight. To combat this I used to block up the rig with lumber blocks of different sizes and as I normally sit for at least two weeks each time I stop (full timer) this worked fine with the exception of getting it perfectly level fore and aft, as well as port to starboard.

Just about a year ago I decided to try screw type jacks to see if they would hold up the bus even though they were rated for only 1500 to 2000 lbs.  Much to my surprise they do!

Now when I stop I try to make sure I am level fore to aft for sure, and as close as possible port to stbd.  If I am not level port to stbd, I use the jacks to level it (it will already be close, within a few degrees) by just letting the jack on the rear high side just touch the jack point, then jacking up the rear low side as needed.  This works because as the rig is under pressure, the 1500 lbs jack WILL raise it a little.  Then I do the forward jacks, again just letting them contact the jacking points, and I'm done.

I've been doing this for the whole year and have not lost one of those jacks yet.  They will not LIFT the dead weight of the rig when  the bags lost pressure but are fine for holding the static weight of the bus.  And no people, I do NOT crawl under the rig with only these jacks holding it up.

The new type of small screw jacks used today are best and easiest to use because they come with heavy eyes on the jack and fairly heavy two piece bar stock with turn handle usable at any angle.  The old style with the folding round stock and flat blade insert into the jack work but are a little bit of a pain due to the "connection" between handle and jack.

Ed
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« Reply #32 on: February 24, 2007, 05:09:24 AM »

Stan, your advice will be followed but it sure sounds like pit work to me.  When I go home in the spring I'll probably drop the bus off with my guy in NC and stick around for a day or so while he does the tests.  I'll build the test rig (or perhaps even 4 of them...can't be that expensive) and we can test all the beams at the same time.

I tried a small screw jack on the left front yesterday even though it was too tall to use a sturdy piece of wood under it.  Since the bus is tilted a bit this morning I expect that I'll find the jack sitting in a depression in the dirt.  But that's OK...every experiment is a character builder.

NCbob
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« Reply #33 on: February 24, 2007, 05:18:36 AM »

NCBob: I guess it depends on how large a belly you have and if you enjoy the challenge of  making things right. If you put your drive wheels on run-up blocks, you should be able to lie on your back under the bus with all the air off the suspension. If you can't do that, don't go under the bus without supporting the bus body, in the raised position, at the jack points.
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« Reply #34 on: February 24, 2007, 10:48:53 AM »

Bob...jacking the bus level at the front may be a bad idea.  If you wish to force it back level, consider jacking at the low side rear jackpoint.  That's where lateral leveling is controlled.

Best, JR
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

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