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Author Topic: rooftop air  (Read 9378 times)
tucsontattoo
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« on: April 18, 2006, 03:36:41 PM »

I have a 4106 conversion with 2 coleman roof air units, also have a onan 25 kw propane powered gen. would like to run my front air sometimes while driving but there seems to be some controversy about runing propane powered gen while moving. i know the way this bus is set up the gen wont start whjle moving. however my propane fridg works fine. is it possable to run this gen while in moton?
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« Reply #1 on: April 18, 2006, 04:07:13 PM »

Yes!
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Nick Badame Refrig/ACC
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« Reply #2 on: April 18, 2006, 04:31:46 PM »

SHAKE PROPANE


IT REFRIGERATES


AND FREEZES!


The Colder It Gets The Lower The PSI !???  Mabe it effects the air to fuel mixture???

That is the extent of my knolage on the subject!

Nick Badame-
« Last Edit: April 18, 2006, 04:35:23 PM by Nick Badame Refrig. Co. » Logged

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« Reply #3 on: April 18, 2006, 05:12:45 PM »

Propane seems to be one of the alternate fuels for vehicles. If you can run a car on propane, I do not see why not a genset. But I am no expert!!
                                     Work?/Play safely Jim
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« Reply #4 on: April 18, 2006, 05:32:40 PM »

Nick,

I have a hard time buying that one. I run my frige all the time underway, no problems, and all those propane powered vehicles don't seem to have problems either.
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« Reply #5 on: April 18, 2006, 05:46:12 PM »

Most propane vehicles use LIQUID taps on the tanks and then heat exchangers to convert to vapor.

If the generator is a vapor-only setup, and liquid was to get into the vapor regulator it would/could
be a problem. But if the generator is fed LIQUID up to a heat exchanger from the tank and if you
have the right type of tank you should not have a problem.

Think Fork Lift tanks with liquid taps and heat exchangers down next to the engines with coolant
circulating to heat the propane to vapor.
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« Reply #6 on: April 18, 2006, 06:07:57 PM »

Gusc,

I just took  past expierences with res, and comm, heaters that if liquid makes it to the regulator, it will freeze up
and I have seen heaters that will actually burn through the heat exchanger if the mixture turns oxygen rich!
Big! Big! Hazzard!!
So, I figured a simular  situation could  Happen!

Nick-

Nick,

I have a hard time buying that one. I run my frige all the time underway, no problems, and all those propane powered vehicles don't seem to have problems either.
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« Reply #7 on: April 18, 2006, 07:11:11 PM »

Unless 30 years old or older, small gensets are vapor units.  Don't work like fork lifts.   I run my fridge on LP when underway...done this for 30 years...may burn the thing up next time too.  Probably not. 
Some states have laws that prohibit LP gas tanks being in "on" position while underway.  Many northeast tunnels prohibit LP period.  OOPS... 
Your generator is 'locked out to comply with the RV safety guidlines.  You may have some liability exposure if the genset caused a fire, and you could have issues with your insurance if you defeat the interlock.  Still, if you ran the generator while underway, it wouldn't be any more of a fire hazard than when parked.  May be less due to additional cooling air while underway.   Be sure that all your flex lines are in good condition....if a fire started when underway, you'd never know it until too late.
Convert that thing to a nice safe diesel generator...and run it all you want!   
How much does it cost to run that propane genset? 
Cheers, JR
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« Reply #8 on: April 22, 2006, 06:36:32 AM »

I run my propane fridge all the time under way, never a problem, as for gen set safety i got to tell you i had a onan deisel in my bus ,it was my first gen set, you know one of those nice safe ones, well on a trip to california it caught fire on the road,nearly lost the whole rig but was able to get the fire out, damage to the bus was min, the investigation into the fire revealed a fuel leak developed at the fuel pump which sprayed fuel all in the compartment, it was in nevada, was a windy day,conditions with  heat and wind and fuel together with hot parts of the engine ignited the fuel, dont assume because its deisel its safe, gen sets running on the road can be a nigt mare for sure. I installed in dash engine driven a/c on mine and rarely operate the gen set even thogh it is brand new. if you go cross country 3000 miles from home in the 100 deg temps with no a/c that get your attn real quick.
Frank Allen
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« Reply #9 on: April 22, 2006, 07:55:34 AM »

If you have a large enough bus system alternator and an inverter you may want to consider this as an option:

I have a tie-solenoid between the house and bus batteries and this allows me to run the front air unit using the inverter. This works perfectly with my ducted air system blasting all of the air to the front of the coach. When the outside temp gets really hot, I start the genset and all three air units. You could hang meat in there if you wanted with all three units on and turned down.
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« Reply #10 on: April 22, 2006, 11:59:17 AM »

Well, I had to sign up for this one, I wasn't going to because I'm not sure I like the Mak board's new format.  But I couldn't resist jumping into this thread, because propane is not one of those topics that will tolerate misinformation.
So here's the scoop.  The three posts above this one have it right.  I'll try to consolidate and add a few comments...

First, Laws aside, running your genset on propane while underway is fine if the system is properly built.  Since it's very unlikely that your genset uses liquid propane, I'll not
comment on that part of it because liquid systems are very different and take a lot more "stuff" to make them safe and proper.  So a vapor system:

(1) Freezing Tanks.
If your tank is too small and you run a genset from it, it will freeze up.  Not from shaking though.  What makes it freeze is that when you draw vapor out of the tank, that vapor has to come from somewhere.  It comes from the liquid, which has to boil to turn into vapor. To boil you must have heat.  Forgetting about boiling things on a stove for a while, how liquids boil is that you put energy into them, and they turn into gas.  Or in the case of propane you use the latent heat already in the liquid to boil it. The energy gets used as the propane boils, and the liquid gets colder.   Propane is a gas at atmospheric pressure, and under a few hundred PSI it's a liquid. So instead of having to put a fire under a propane tank to make it boil, all you have to do is draw some gas out of the tank, the internal pressure reduces a bit, some liquid propane boils to replace what you've just removed, and the liquid gets a bit colder because the energy to boil it just came from the latent heat stored in the liquid.  Make sense?  Bottom line, if you're just using a little bit of propane from a big tank, it will never cool the tank down enough to freeze it.  If you're using a lot of propane from a small tank, the tank will freeze. 
  When a tank "freezes', the temperature and vapor pressure of the propane inside goes down and down to the point it won't boil anymore... tank frozen, no more gas will come out 'till it heats up again.  So for things that draw a lot of propane like cars and forklifts, it's a much better soultion to draw the propane out of the tank as a liquid and boil it externally using an external heat source like engine coolant via a heat exchanger... that way tank freeze ups are never an issue and you can draw as much out as you want.

Propane refrigerators are never an issue in an RV because they never draw enough out of a tank to freeze it. Same for stoves.  Gensets are ok but depending on your tank size and generator size, it's often "on the line".  A fully loaded 20KW genset will definitely freeze up a 5 gallon BBQ tank in short order.  But if the tank is 100 gallons, there'd never be a problem because the surface area of that big tank will transfer enough ambient heat into the liquid inside to keep it warm enough to work fine.  Somewhere inbetween, you'll find that your tank size/genset combo will work or not... the solution if it freezes is to use less electricity or get a bigger tank.

Ok, so much for that.  Now "ON THE ROAD"
And while I'm at it, FILLING PROPANE TANKS, because it all relates....

   Basically all the arguements for getting liquid propane accidentally into your genset's regulator are valid... it could cause trouble.
HOWEVER a properly designed tank system will limit your ability to fill it, to about 85% max. That leaves a lot of "slosh" room in the top of the tank, and even on a bumpy road or going up a grade, it's very unlikely that enough liquid if any will be able to get up to the top of the tank where the vapor is drawn out, and into the outlet, to do any damage. Unlikely I say, but not impossible.
If your vapor outlet is not right at the top of the tank, it's possible that liquid could get into it.  This happens when tanks are improperly mounted.
If you overfill your tank or the jerk at the propane station overfills it (called "stuffing in the propane industry) and there's little airspace left inside, yes liquid propane can and will probably get into your system.  But at that point you have a LOT more to worry about, because if the day heats up much at all, the liquid propane inside is going to expand and have nowhere to go, and  you're going to have a venting propane tank on your hands.  That will turn your "genset regulator getting liquid into it" into a problem that you won't even have to think about, because it's likely that you'll have a major fire or disaster on your hands that will make your genset problems trivial at that point.  Venting propane tanks are no fun and absolutely dangerous...you really never want to see one do it firsthand. Beleieve me, because I've seen it. Nasty.
 
 Bottom line, if the tank is NEVER overfilled, and your vapor outlet comes off the very top of the tank as it should, you'll never have problems getting liquid into your genset.
BEWARE- many larger propane tanks do not have OPD valves (overfill protection devices) as they are not required.  This means that the jerk at the propane station can and often will "stuff" your tank.  I've had it happen probably 15-20 times.  Some guys are good about it but face it, guys who work at filling stations are usually not rocket scientists, and many are clueless about the dangers of stuffing a tank.  Have you ever watched the guy see the 'pee" valve go off, then shut it and top your tank off to the next nearest gallon? Yup, the guy should be fired.  Dangerous.  As SOON as that pee valve makes white, the filling should be STOPPED right then and there.  NO FUDGING.
These days I watch the guys like a hawk and if they try to stuff the tank, I simpy reach over and turn the valve off myself.  If they argue, they loose. And it still happens...!!!

SAFETY SYSTEMS for PROPANE
TO be safe, there's a few things you should do, (A) to comply with some codes and (B) just for common sense.

(1) SHUTOFF VALVES:  Besides a shutoff valve on each appliance and a main shutoff valve as well, there should be an electrically operated solenoid shutoff valve placed just on the inlet of the genset, so that when the genset is turned off, the valve shuts. This is code and it's also common sense-necessary. You don't want your genset regulator leaking propane thru the system when the generator isn't running.

(2) TANK VENT:  Something most people don't know and unfortunately even the ones who do know, don't often do, is this:
There is a DOT regulation (It's been 20 years now and I don't remember the number) that says if you have a permanently mounted propane tank on your RV or propane powered vehicle, that you hard-pipe the tank overpressure relief vent out to the rear of the vehicle and aim it up at 45 degrees.  This is so that if the tank vents for any reason, the resulting plume of propane will exit out the rear of the vehicle and up, rather than under it where it puddle up, wait for a little spark and likely go *boom*.
  It's pretty easy to do- just plumb some 3/4" galvanized pipe from the tank to the rear of the vehicle and put a 45 on the end aiming up, and silicone a little cork in the hole.  Should it ever be necessary for the tank to vent, you'll be glad you did it!!!

(3) SAFETY SENSORS:  If you have propane on an RV, you'd be a total fool to not take advantage of the nice inexpensive safety detector devices avaliable these days, namely propane vapor detector alarm systems and CO detector alarm systems.  You should install both in appropriate places in your RV.  The propane sensors can also be had that automatically shut the main off if raw propane is detected, and those are the better ones if you can work them into your system.  Propane is heavier than air, so sensors should be mounted low in the space, like below knee level or on the floor.
And there's absolutely NO excuse for not having at least one CO monitor near your head where you breathe as you sleep.  Cheap insurance and keeps you alive if you have a problem.

(4) SO, running gensets on the road? If you have done the above homework and your system is proper, there's no reason not to do it except some codes (which I will acknowledge but not necessarily agree with).  Same goes with running the fridge while on the road.  Doing either is not as safe or as legal as shutting your propane system down when you drive, but that's your call not mine.  Personally? I do both. Never a problem.

(5) Where do I come from, preaching all this stuff ?  I've been involved in propane conversions of vehicles and small engines for 15 years now.  I've been through an intensive two-week propane school put on by the IMPCO corporation.  I use propane daily and work with propane systems that range from RV's to glassblowing torches to systems that create giant 200 foot propane fire-tornados.  None of this makes me an expert, that's for sure (expert=unknown drip under pressure) but I do understand the stuff and I've also seen what happens when you don't give it the respect it deserves. (kaboom, and all the windows gone for a three block radius, just from filling an RV tank under the wrong circumstances..no, it wasn't me, I was at my business two blocks away at the time )

My bus? 110 gallon propane tank, propane water heater, propane living space heater, propane stove, 8kw propane genset, propane fridge.  I run the fridge on the road 100% of the time and the genset often on really hot days.  I have two propane detectors, two CO detectors, the required hard-plummed tank vent system, and all the valves I should.  Whole thing is done in 3/4 pipe with stainless steel bellows style hoses between the piping and the appliances (If you use these make sure they are rated for RV use... many are not and won't hold up to the vibration)
So do it right, be safe
« Last Edit: April 22, 2006, 12:02:09 PM by boogiethecat » Logged

1962 Crown
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« Reply #11 on: April 22, 2006, 02:42:19 PM »

THANKS for signing on and providing the info BTC
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belfert
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« Reply #12 on: April 24, 2006, 05:59:13 AM »

My bus? 110 gallon propane tank, propane water heater, propane living space heater, propane stove, 8kw propane genset, propane fridge.  I run the fridge on the road 100% of the time and the genset often on really hot days.  I have two propane detectors, two CO detectors, the required hard-plummed tank vent system, and all the valves I should.  Whole thing is done in 3/4 pipe with stainless steel bellows style hoses between the piping and the appliances (If you use these make sure they are rated for RV use... many are not and won't hold up to the vibration)
So do it right, be safe

What are your thoughts on using something like Pro-Flex CSST tubing for propane in a bus conversion?  Will it handle the vibration?  RV makers use a fair amount of copper for propane and I personally don't like that idea.

Brian Elfert
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« Reply #13 on: April 24, 2006, 06:22:43 AM »

Well, I had to sign up for this one, I wasn't going to because I'm not sure I like the Mak board's new format.  But I couldn't resist jumping into this thread, because propane is not one of those topics that will tolerate misinformation.

Now see, that was not so hard, and welcome to the board. Your posts are always informative and welcome. Thanks for the valuable information on propane.
Richard
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« Reply #14 on: April 24, 2006, 06:31:16 AM »

Finally, some advice a guy can believe.
Thanks for the post boogiethecat.

I do however take issue with one item.
"expert(ekspert) prep. a hasbeen ( ie:washed up ), combined with: drip ( ignoramice) under pressure( stressed out)".
 Grin

Now if we could just get some respectable electrical advice.
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« Reply #15 on: April 26, 2006, 06:29:36 PM »

Brian, I'm not too familiar with Proflex CSST.  My thoughts anyway:

Flexible stainless tubing can be made to be simply flexible- for easy installation but basically to be bent once or twice and that's it, and then it can be made to withstand constant vibration.  Two different things.  Unless Proflex is specifically rated for RV use, legally it shouldn't be used.   Ok, that said, if you were to use it anyway, and you did a clean job and tied it down every foot or two so that it couldn't vibrate, it would likely outlast you and your bus without problem.  Personally I would have little hesitation using it, but I'd make darned sure it's strapped down well everywhere and there were no hanging ends that could wiggle as you drive down the road.
 But just remember that if it's not rated for non-stationary use, and if you use it, have a problem and get the clip-board holders in the equation, you may wish you didn't.  You know how that goes.   Check with the companies that make it... maybe there is some that is rated for RV. That would certainly be slick....
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« Reply #16 on: April 27, 2006, 11:35:10 AM »

Couple questions:
I would think running copper tubing for the rear vent would work? Kinda nervous about venting a propane tank that close to my diesel's air intake. Would it be better to vent it low so your first sign the propane tank is venting isn't that the engines running away and going boom? I'm thinking of it venting while running down the road...

Also, would a propane sensor by the tank be smart or are you just asking for alarms all the time?

Jason Whitaker
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« Reply #17 on: April 27, 2006, 04:51:47 PM »

Copper tubing for the rear vent would be fine.  As long as it doesn't come apart, so solder the joints well and don't use compression fittings.   3/4" minimum is what I remember to be the spec.  If your bus isn't finished yet you may find iron pipe to be pretty easy to do.  And I use a short piece of propane rated hose or even RV rated stainless bellows hose to couple between the tanks' vent and the piping system, just to be sure movement of the tank doesn't break the pipes.
The best place to exit the pipe is as high as you can on the rear.  That way the stuff goes up and out.  I doubt it would get into your engine's intake... in fact it's likely it will never ever vent at all but if it does, you'll be glad its there...

Oh.. venting low... there's a very good reason not to do that.  I wish I had a copy... I actually saw a video of a guy who's truck tank vented, the vent valve got stuck in the "open" mode, and then the plume caught on fire.  He had a 100 gallon tank and the flame plume went up about 20 feet and back about 30 feet.  Fortunately for the guy, he was  on the freeway when it happened, and he simply drove until the tank refrigerated and the plume went out.  Had it been vented "low", it would have certainly toasted anyone behind him.  As it was, no-one was hurt and a spectacular video was created!! What a rooster tail!!!

Propane sensors near the tank are certainly a good idea if you expect leaks there.  During filling I'd guess they'd go off like crazy, because of the pee valve.
The biggest thing you DON"T want to happen is have propane puddle up somewhere (remember it's heavier than air and though invisible, it behaves a lot like water in it's puddling ability).  So mostly propane sensors are handy in places like inside your bus, in cubby holes where water heaters are installed, under the stove, under the fridge... any place a leak is likely to cause a puddle, you want to know about it.  Outside if the tank is hanging on the frame like mine, or in a religious bay ( has a very holy bottom) you'd probably be ok without a sensor although they can never hurt... if there's a problem they'll let you know and you can deal with it in ways much friendlier than "boom".
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« Reply #18 on: April 27, 2006, 08:30:53 PM »

Unless 30 years old or older, small gensets are vapor units.  Don't work like fork lifts. 
My 1989 Executive diesel came with a liquid propane Onan, it is only half that old.  Not sure when they quit making them, but was more recent than 30 years!
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« Reply #19 on: April 30, 2006, 05:45:40 PM »

Unless 30 years old or older, small gensets are vapor units.  Don't work like fork lifts. 
My 1989 Executive diesel came with a liquid propane Onan, it is only half that old. Not sure when they quit making them, but was more recent than 30 years!

Actually, I misspoke.  I was referring to the small RV and home gensets that are less than 7.5, or thereabouts.   Onan and several other manufacturers still offer liquid propane format...if specified, in smallish gensets.    Usually  the units are 10KW or larger, but Onan will set up a liquid 6.5 if one wants such.   They are generally, but as you state, not always,  used for stationary applications.   They are rare in MH applications.   Exectutive obviously did it that way. 
Lliquid propane avoids of  the supply tank freeze-up issues.   Liquid propane is likely an easier starting generator in cold weather also.  Vapor generators can be cantankerous in cold weather.   
Downside for all propane units in comparison to  gasoline or diesel is the reduced output for propane powered gensets.  They are rated down as much as 30%. 
Upside, LP unit don't require much maintenence.   They will sit for several years and fire right up.  So will a diesel...don't even think about doing that with a gasoline unit. 
Diesel is the safest fuel, gasoline is probably the next safest?   A liquid propane unit would seem to be by far the most complicated, and likely the most unsafe of all.   Liquid propane units have quite a few extra parts, and supply systems (one for all the RV systems and a dedicated liquid line)  that add complexity to the system.   Not something a backyard mechanic should be trying to repair.  IMHO. 
Why would anyone want an LP genset..why other than the lack of maintenence?   There cannot be any more expensive fuel for a generator?  I must be missing something!   Of course, if one is able to afford an Executive MH, the cost of genset fuel ain't an issue!

JR
 

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« Reply #20 on: April 30, 2006, 05:57:08 PM »

I have a 4106 conversion with 2 coleman roof air units, also have a onan 25 kw propane powered gen. would like to

OOOOOOOOOOOOOOOHHH! Shocked   I really misread the original post....25KW Onan...that's a BIG generator!  May well be a liquid propane uint!   
How's the decision regarding operating the ACs while underway going?  Is there a resolution?
JR
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« Reply #21 on: May 07, 2006, 12:29:55 AM »

I have a 4106 conversion with 2 coleman roof air units, also have a onan 25 kw propane powered gen. would like to

OOOOOOOOOOOOOOOHHH! Shocked   I really misread the original post....25KW Onan...that's a BIG generator!  May well be a liquid propane uint!   
How's the decision regarding operating the ACs while underway going?  Is there a resolution?
JR

    Thanks for asking, was begining to wonder if it had something to do with my copper tubing.
 I think the original owner/builder must have installed some sort of motion switch as a safty device to stop the gen set from being used while driving. will tear into it next wednesday and see what I can find. has to be something simpel   Greg
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« Reply #22 on: May 07, 2006, 06:37:40 PM »

Quote
    Thanks for asking, was begining to wonder if it had something to do with my copper tubing.
 I think the original owner/builder must have installed some sort of motion switch as a safty device to stop the gen set from being used while driving. will tear into it next wednesday and see what I can find. has to be something simpel   Greg
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I doubt it's a motion switch.  Does the generator not "start"...or not "run" when the offending interlock is activated?   Start the generator and see what happens when the bus engine is started.  What does the genset  do when you put it in gear?  Does it cut the ignition off, or turn the gas off and the generato dies slowly?  If the generator runs with the engine running but cuts off when placed in gear, there's a connection to the neutral switch on the shifter.  Or...if it won't run when the bus engine's running, there's an interlock on the bus ignition master.  An ignition interlock is the most likely.   May be more sopisticated and sense alt ouput or coach engine oil pressure.     
Look for an extra wire going to the generator or the remote control panel.    I don't know what model genset you have, but I'll bet finding the interlock won't be too difficult.     See what knocks off the genset and post the results...will make resolution easier. 
Don't forget the liability issue associated with defeating the genset interlock switch.   
May want to visualize all of your LP supply lines and system, especially flex lines (and if liquid system, all of the components related to that) in the generator compartment, for any possible problems that may cause leaks.    
\\An LP leak detector, attached to a cutoff solenoid and alarm,  in the genset box would be a good idea.
Best, JR
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« Reply #23 on: May 08, 2006, 01:50:56 AM »

JR   
I;m currently going through the huge box of paperwork and receipts I was given when I bought the bus, hope to find some clues to what all I'm dealing with as far as components, I do have an alarm system, not sure it has propane sniffers or not yet, still reading. Have spoken with a local RV service shop, they were also puzzled  by the problem. One lead I,m following was the gen set may have too much oil in the crank case,, sounded totally unrelated but a quick read of the owners manual seems to reinforce this. go figure? They tell me ( they the RV repair shop) that older Onans are real touchy about this!!My only personal exp. with this problem is that it won't start while moving. A call to the fellow I bought it from confirmed this. He says if you start the gen. an then pull out the gen. will keep running for a while but eventually shut down.
   Thanks for the thoughts on starting the gen. and then starting the bus, and how exactly does it die. Should tell me allot. Will let you know Wednesday what more I,ve learned             

                                                          Thanks again for your input   Greg
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« Reply #24 on: May 08, 2006, 04:36:58 AM »

Greg,

This may be a shot in the dark, but here goes.

We had a bunch of Onans on commercial bucket trucks and one thing we found was that the low oil warning sensor was very sensitive.
 
Even though they measured full we had to tilt them and over fill a little so that they would stay running when the vehicles were moving.

FWIW!

Cliff
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« Reply #25 on: May 08, 2006, 08:23:35 PM »

Yep.  I agree with Cliff...seems like a little too much oil wouldn't shut it down...unless the oil is foaming up and getting sucked thru a crankcase breather.  Low oil sensor may cut it off if low...or sensor is bad.  Verify that the genset has proper oil level and disconnect (disable) the low oil sensor and see if it still dies when the bus engine is running or the bus is moving. 
Interesting problem.   You'll get it figured out.  How and when it shuts down will enable additional diagnostics! 
Best, JR
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« Reply #26 on: May 08, 2006, 08:26:30 PM »

One other thing comes to mind...the propane alarm.    Propane sniffers are famous for false alarms and shutting off LP.   
You may have an auto LP shutdown with a sniffer in genset box or nearby...or even inside the bus.   
JR
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« Reply #27 on: May 09, 2006, 12:15:16 PM »

 Well, home today and trying to figure whats shuting the gen down.. so far checked oil for over full.....not.  started gen then turned on main power ....... gen still running,  started engine...gen stillrunning..... brought rpm up to 1500.... gen still running,  back to idel placed transmission in reverse..... gen still running,  placed transmission in drive.... still running. Have not tried stoping and restarting gen with bus engine running or while driving, will try that next and see if I can get it to die.The fellow I bought the bus from says it die after you start driving,sometimes sooner sometimes later and won't restart without stoping. dosen't sound like an inter lock to me ,sounds more like a loose wire on an interlock. will let you know what I learn next later tonight. Thank Cliff and JR, this thing has me pulling my hair a little...        Greg
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« Reply #28 on: May 09, 2006, 12:48:10 PM »

Well, home today and trying to figure whats shuting the gen down.. so far checked oil for over full.....not. started gen then turned on main power ....... gen still running, started engine...gen stillrunning..... brought rpm up to 1500.... gen still running, back to idel placed transmission in reverse..... gen still running, placed transmission in drive.... still running. Have not tried stoping and restarting gen with bus engine running or while driving, will try that next and see if I can get it to die.The fellow I bought the bus from says it die after you start driving,sometimes sooner sometimes later and won't restart without stoping. dosen't sound like an inter lock to me ,sounds more like a loose wire on an interlock. will let you know what I learn next later tonight. Thank Cliff and JR, this thing has me pulling my hair a little... Greg

I had a similar problem with my genset when I first got DML. The unit would just stop sometimes while driving.
I finally found an overtemp shutdown in the system. It was a Wrico Diesel 10 kw. The coolant in the genset was plumbed into the coach's coolant and if the coach got up to about 190-200 the genset would shut down. I think the O/T sensor on the genset was at 215 degrees, but due to lack of proper circulation, the genset was running hotter than the coach. Also, while sitting in the desert with the genset running it would sometimes quit after an hour or so.

I did two things to solve the problem. One, I installed a circulationg pump to assist the pump on the genset to get additional water flow to the radiator and back. Second, I installed two 16 inch electric fans on the coach radiator with a 190 degree thermostat to turn them on. Those two actions cured my genset problem.
Richard
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« Reply #29 on: May 09, 2006, 12:59:54 PM »

   Now I've tried stopping and restarting under all the above conditions, still running fine. this problem only seems to be happening with the bus moving. I'm fresh outta ideas. will drive tonight first with the gen. running and see how long it lasts.If I don't get a stop I will shutdown and try to restart. Don't know how  much that will tell me but at this point I'm beginning to think there is nothing wrong, just want to see it do it again!!!
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« Reply #30 on: May 09, 2006, 01:07:38 PM »

Drivingmisslazy
   Thanks for the input> I have a 4 KW Onan (air cooled) running on propane. All other propane app. in the coach run fine. Gen. will not start  or continue to run while moving. Cannot duplicate the problem under any stationary conditions.Any ideas?Huh?
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« Reply #31 on: May 09, 2006, 02:26:24 PM »

Perhaps bus aerodynamics are causing a reduction in air flow across the generator when running, causing the overtemp switch to shut down the generator?  Cooler day would allow it to run longer before shutting down.  Jack
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« Reply #32 on: May 09, 2006, 03:29:20 PM »

Hummmmmm  just might happen, will look into it!

                                       Greg
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« Reply #33 on: May 09, 2006, 04:00:15 PM »

Nope not an over heat thing, Won't start while moving with the gen dead cold. Gonna keep lookin.........
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« Reply #34 on: May 09, 2006, 07:28:30 PM »

How long after you're driving does it shut down?  When it won't start, is it turning over and not lighting up.....or does the starter not turn the engine?   
Where does your liquid line exit from the LP tank?   Out the top of the tank?  Have you tried topping off the LP tank? 
Is anything electrical running off the genset when it shuts down? 
Jack seems to offer the most plausible idea so far...there have been liquid cooled gensets that wouldn't cool when driving at highway speeds...the airflow thru the radiator was "reversed" or "cavitating" due to aerodynamics of the bus body when underway. 
I assume that there are no valves or solenoids in the generator line between the LP tank and the generator?  The liquid line may have a faulty pickup, yet the "vapor" RV  appliances are  fed with another line and would  continue to work.  If the liquid line surged or slugged vapor, the engine would quit.  If a solenoid cut it off, the engine would still run for a good bit before it ran out of fuel.   This is a liquid LP unit?? As opposed to a vapor gas unit.   I believe we covered this early on.   
Are any removeable bus body covers that are  convering the generator?  The genset box factory covers must remain in place to cool correctly.   If no solenoids and the LP tank is 75% or better, I'd put my money on heating.   
While you may not wish to fool with this idea, but maybe a line could be attached to the overheat switch so that it's function could be monitored from some vantage point inside the bus.   Could be the generator head overheating and shutting the engine down...?   Not sure that Onan has overheat protection on the gen head. 
Be gone for a few days...expect to hear that this problem has been resolved when I return! 
Stumped, JR  Huh
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« Reply #35 on: May 09, 2006, 07:38:03 PM »

Just one more thing...if this is a liquid line genset, do any of the LP components require accurate barometric pressure (converter, regulator?) to function?  Someone familiar with liquid line small engines would know the answer to this.   The airflow thru the generator box may be affecting such sytem components.  My guess would be that the baro pressure would be significantly reduced when underway.  This would be especially true if the unit is behind a large mudflap. 
If the unit won't start, but turns over at highway speeds....try sealing up the generator box completely so that the bus airflow cannot act on the LP components...try starting it.  If it starts...viola...if not, forget this tack.   If it starts, the point is made, turn it immediately off before it heats up.   This seems to have been a problem from the gitgo.  Was this a professsional conversion, and if so, is the converter still around??? Or any of their conversions with similar generator setup.  May be some interesting history.
Best, JR
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« Reply #36 on: May 11, 2006, 08:51:14 PM »

OK.... Here is the latest   When I got the bus the fellow I got it from had re skined the doors on the bays doing away with the intake grill for the gen set bay.Figured with the bottom of the gen box open it wouldnt matter. Add to that picture the fellow who built the coach thought it would help his cooling to leave the bottom of the sound box wide open.Then.....somewhere along the way someone added a fome filter cover to the air cleaner element NOW... I start the gen set, turn on the ac's and drive down the 2 lane about 45 or 50 all is well... Hit the interstate and bring her up to about 60  still running fine. Push her over in the fast lane run her up to about 65 and no more gen... I was pulling a vacume on the sound box with a restricted air intake, so the vacume accuated propane regulater feeding gen engine shuts off fule to engine.....That is what it was.Not movtng, just moving fast!!! Fianly figured it all out, Couldn't have done it with all the thoughts and mabie its the kinda input you guys came up with, Thanks so much for all your help. Goterdone

                                           Greg


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« Reply #37 on: May 12, 2006, 05:10:55 AM »

Greg,

Excellent news and good troubleshooting.

Its always an extra challenge when you have to unfix what others have fixed.

Cliff
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« Reply #38 on: May 12, 2006, 09:37:50 AM »

  Amen to that Cliff,  Thanks  to Jr's input and your input I was able to move through all the possibilities allot faster. What really got me thinking was an old picture of my bus before the new door skins were installed. I think the final fix will be to have louvers cut for the cooling air intake and I'm going to plumb the engine (gen set) air intake through the sound box wall so I'm drawing intake air from inside the bay and not from inside the sound box.

                                                               Greg
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