I was unable to determine the problem myself, so I took the coach to an Onan-approved service place. Verdict? Bad LP regulator, which was no surprise to me.
Problem? Regulator no longer available from Onan, Rebuild kit no longer available from Onan. Nothing looking like it on Ebay.
Is there something else, a part from a later year generator perhaps. that I can substitute for the bad regulator? I would think if it flows enough and regulates to the right range, anything would be adaptable, but I don't know much about this stuff.
oldMattB
Give a picture of it or a part #
Waiting to hear from shop for a part number - it is about an hour away.
Generator is a 6.5 nhmfa26115c
oldMattB
I can't believe that Onan doesn't know what to replace it with???
from the manual, best I can do right now
A little research comes up with a part # of 305826 for your regulator. 2 versions available from these folk. Seem to know their stuff: Flight Systems 800.403.3728 Plastic one $200.00 metal one $250.00. Confirm everything before you buy as to model # of genny etc.
Keith
Generator Accessories | Generator Exercise Monitor (http://www.flightsystems.com/generator_exercise_monitor.htm)
This was back in 2004, but from my notes: Overhaul propane regulator impco RKJ-2 kit 201017 kit $47.
This was for my: Onan 6.5NHMFA26116C. Serial # B920449612
Brett
@Keith,
I think you are referring to the voltage regulator, part number 305-0826. I am looking for the LP regulator.
@ Brett
I searched for "201017," "RKJ-2," "RKJ-2 kit 20107" and did not seem to find anything that looked like LP regulator parts. Is the Imco you wrote of Imco Trailer, Imco Marine, IMCO Inc. or another?
oldMattB
Maybe Impco?
Onan gave the shop the part number 148-0964.
Yes, sorry, it is Impco. Will change it on post above incase others need the correct name.
Brett
It seems that Brett's number RKJ-2 (sometimes RK-J-2), is an Impco Model J two-stage regulator for forklifts. I do not have my dead one with me, but the Impco sure looks like it. If so, these are commonly available for about $65 new, with the rebuild kit at $28.
How could we verify this? This is much better than the $200 to not available I have read and heard of.
oldMattB
Matt,
OK misread the regulator!
I have spoken with the person below who was most helpful. He said no mystery to all this. It's almost certainly the item Brett posted. Give him a call and he can confirm it and send you the correct kit/part:
Bob 800-221-8467
Moulden Supply Co. Inc. - Home (http://www.mouldensupply.com/)
Keith
Be sure if you overhaul it that you spec the high-temperature/silicone diaphragm.
Brett
Thanks all!
I have provided the info to the shop. I do not know how far from the official Onan recommended part they will go, but they will call Onan and check it out.
I compared the specs and the exploded diagram of the Onan part and the Model J, and they seem identical. Is the high-temperature diaphragm necessary because of the close proximity to the generator block?
If the shop cannot get this far afield, I will call Moulden.
oldMattB
Capstone:
Got the coach back from the shop. Onan told the shop that the LP regulator and the rebuild kit are no longer available. My research indicated that the Onan part is the same as the IMPCO Model J and Model K, which are common forklift regulators. The shop verified this with Onan and the IMPCO supplier, and discovered that IMPCO supplied the regulators for Onan. The shop installed one of these, and the gen is happy! The newest model is the Cobra, which is said to be identical in function. The Cobra is commonly available - I saw one on eBay for under $30, average price about $60.
I estimate that someone could unbolt the generator and pull it onto a skid, leaving the hoses and electrical cord attached, take off the shrouds, replace the regulator and reinstall in about two hours. Having R&R-ed the gen a couple of times, I could probably now do the job in less than one hour.
Hope this helps someone!
oldMattB
Excellent.
As stated before, you need to verify that the regulator/overhaul kit is made for HIGH TEMPERATURE locations. The difference is a special silicone diaphragm. The "regular"/low temperature regulators would be for installations outside the generator where they are not exposed to the high heat found inside the generator itself.
Brett
Brett,
The kit you listed earlier, the RJK-2, includes the silicone diaphragm. The Model J-2 regulator is built with the silicone diaphragm, the Model J has a hydrin diaphragm. The Cobra model appears to come standard with a silicone diaphragm.
oldMattB
Excellent. Will file that in case mine ever goes out.
Brett
OK, Ive been having the same LP generator issues as was reported in the topic.
When I purchase the coach in May it worked fine. had 1/2 tank or propane and ran fine for about 1500mi. Tanks was below 1/4 so I filled it in Utah (I think). ran until that evening then stopped when a load was applied. Stopped by Onan in ID and they could not find what was wrong. by then it would run for a short time, add a load and it would act like it had no fuel. Been that way since. If no load it will run for maybe 10 mi, if loaded dies in seconds. Oil seems low so I added some-no help! Today I Pulled the Onan 6500 Marquis and got at the Regulator. That is a job getting it out and onto a lift. to get the top cover off. Has on it "IMPCO Model J" and onan part # 148-0964. Here is a pic. I plan on getting another model J and a silicon rebuild kit :)
HI,
I have had this problem twice. When you run the propane tank low or empty, the oily scent stuff that gives propane a smell and has collected in the bottom of the tank over the years, will be drawn up and collect in the model j. This will gum up the inside of the regulator. You will need a kit just because you will tear up the gaskets, and diaphragm to clean it. Be sure which way you go, new model j or rebuild your old one, that you keep the RED spring on the gas valve. The new model j will not have this RED spring unless it is made for an onan generator. With out the RED spring in the model j, the generator will be had to start, it will run poorly. My onan genset is a 6.5NHMFA26115c.
Pat,
Thanks Pat.
I have the same Genny and coach :)
I plan on converting it to run on the High pressure vapor side as opposed to the liquid as soon as I fix the regulator. I have heard that on vapor this is never a problem again :)
I have the manuals for the Onan and some of the drawings and schematics for the coach., but am always looking for more.
If you want to share or set up a drawing file for the '95 U240, let me know,
Joe
Actually, the gasket set to OH the generator propane regulator has a silicone DIAPHRAGM. They are for high temp applications. Being inside the generator itself, you need the high temp gasket set.
This is NOT a difficult job. Been there, done that AND converted to high pressure VAPOR at the suggestion of an engineer at Marshall Gas. VERY interesting hour at their HQ.
I think I have confirmed that the Regulator is the problem
Redish brown gunk is ooozing out of the top fittings while sitting horizontal on the desk
The subject of "oil in the propane lines" has come up here in the past. Link below to some old discussions if you're interested.
Oil Accumulation in Propane System (https://www.foreforums.com/index.php?topic=40088.msg396523#msg396523)
Last time this happened to me was about 6 months ago. I had to replace the stainless steel line on top of the exhaust manifold caused by the oil drying in the line and stopping it up. I tried all kinds of ways and things to unstop it. None worked. The new line was $150.00. I have not had any problems with the flexiable hose coming from the tank.
Pat,
OK, I finally got time to rebuild the Onan Propane Regulator,
I'm rebuilding per the kit from IMPCO.
First, the kit has NO springs so I'm reusing the old ones.
Definitely plugged up with the goo from the bottom of the tank. Will be getting the tank cleaned if I can and changing the Generator to run off the High pressure vapor side of the tank.
One thing seems odd. the NEW regulator I purchased seems identical to the part#184-0964 I pulled off the genny EXCEPT for the input line to the regulator(#8) from the Shutoff valve (#15) on the drawing attached. This input line has a smaller sized 90° screw to flare fitting and I did not notice until I took off the fitting that the port seems to be a water (cooling or heating) tube thru the regulator with, AFAICT, NO port inside for the liquid(gas) propane to get into the reg and thru to the output port at #9 that goes to the input to the carb. The NEW regulator is open from the #8 input to the opposite side and you can see thru it. The OLD reg has this tube blocked, but I cannot see where the propane would go into the main body of the reg and thus to the output of the reg.
Seems odd, but I am rebuilding it to was. Perhaps whatever port there is is plugged as I could pressurize either end of the blocked "water tube" in the OLD or by manually blocking the tube on the new reg and sense no leak. I may call IMPCO tomorrow.
IAC here are some pics.
No need to clean the tank if you switch to high pressure vapor. Those longer hydrocarbon chain "contaminants" will not vaporize, so will not get into the regulator.
thanks Brett:)
FWIW if you use liquid propane fast enough you need to provide engine heat to vaporize the propane.
The pic shows the delivery tube wrapped around the exhaust for heat .
It does indeed!
As the expansion rate of LPG is 270then there should be a SMALL hole that allows the LP (or G) into the body of the regulator.
I want to make sure that THAT hole is clear before I reassemble the reg.
OK, called Impco, no real help there, but Intella helped a lot.
It looks like the casting for the model J Regulators that we use has a connection to the input port that later casting don't have. Later castings use that port as a water flow to cool or heat the regulator. The NEW reg I purchased is like this, other that that it looks identical. It seems like a new reg could be used but change the input to the side LPG IN port that is plugged on the earlier Model J's. There is still an issue of the correct spring for Onan use, but I'm talking to Intella about that.
Thanks. Now I see it. I was wondering what was the loop's purpose. I was stuck on engine coolant being used to heat the liquid propane. You know, the technology with which I'm familiar.
Yes, "feeding" the on-generator propane regulator with liquid LP does require some heating or the regulator could freeze up.
Switching to high pressure vapor should eliminate that issue unless extremely cold conditions. At least, once I converted ours to vapor, never hand an issue of any kind.
Can't help with "new" vs OE, as all I did was overhaul the OE regulator using the high temp kit.
Ya, I'm trying to see if Intella can provide an off the shelf reg that would replace the original with no changes.
The rebuild kit seems fine, but NO replacement springs. Just reusing the originals:)
Hi all,
I realize this post is a few years old but it addresses a concern I am also having with my 1995 Onan Marquis 6500.
Mine also has the exhaust heated tube.
My problem is also similar to a previous poster in that the generator will run but when a large load (a/c) is applied the gen will stumble and shut down.
Although I think (pretty sure) the a/c has issues of it's own, the a/c will run on utility (50a shore power) but doesn't seem to be quite right.
I have dropped the generator, while still keeping the connections, to be able to make repairs and test on the coach.
I have already dropped and cleaned the filter where the liquid line comes in. There was some dust/debris/crumbs in the bottom of the bowl, but the "stone" filter appeared good. I cleaned and blew out the filter with brake clean and re installed it.
There appears to be some "goo" leaking around the lp regulator test(?) plug.
I would post pics, but not sure how to do this yet.
Any thoughts?
Thanks for having me,
Bruce
Bruce,
Welcome to the ForeForum.
There are overhaul kits for the propane regulator. Be sure to order the high temp (silicone) ones, since it is in a high-heat location.
And, yes, as many of us have done, at the propane tank change the line that supplies the generator from liquid LP to high pressure vapor (T in between vapor port on the tank and the house propane regulator). The long hydrocarbon chain contaminants that clog the on-generator do not "evaporate" and get into the vapor port nearly as easily as in the liquid port.
Thank you for replying.
Do you have a preferred source, for these kits?
I can search the internet, but really like to rely of the success of others to guide me.
A link or part number would be perfect.
You will need to verify, as this information is 20 years old (good grief does time fly):
Impco RKJ-2 kit 201017 kit w silicone diaphragm $47. Model J-2 regulator includes silicone diaphragm.
I found these links pretty easily:
Impco RK-J-2 Pressure Regulator Repair Kit - IMS Supply (https://www.imssupply.com/catalog/impco/rk-j-2.html)
IMPCO REPAIR REBUILD KIT MODEL RK-J-2 REGULATOR VAPORIZER SILICONE DIA –... (https://store.nashfuel.com/products/impco-repair-rebuild-kit-model-rk-j-2-regulator-vaporizer-silicone-diaphragm-jb?variant=41443929915549)
They seem to be correct(?)
Do you concur?
Sorry to be a bother.
The one place was out of stock, the other was a week behind in shipping and only showed one.
This place says they have over 200 of these kits.
RK-J-2-IMP IMPCO Propane Repair Kit for Model J, Silicone Diaphragm -... (https://www.ombwarehouse.com/rk-j-2-imp-impco-propane-repair-kit-for-model-j-silicone-diaphragm.html)
The number is slightly different.
Do you think it is a suitable fit? Or is the rest of the number (RKJ-2 kit 201017 ) important?
Sorry, I know nothing about the quality of Helmar parts. If you can't find the Impco parts, may be worth exploring.
I would call your local Propane Dealer (the real dealer, not a station that sells propane). That is who ordered one for me. They likely have a completely different list of wholesalers they deal with.
Also, contact Imco and ask where you can get the proper Impco part.
I rolled the dice and ordered the kit I linked that had it.
I pulled the old reg and dumped a nice puddle of oil in my crotch without realizing it.
After I crawled out I dumped some more on the floor, then I dumped at least another teaspoonful into a pan (less in the pan than on me and the floor, as is the usual case🤣).
Kinda considering reinstalling to see if the several teaspoons is what was causing my low gen engine power.
Reg being "sluggish" perhaps??
Well, since I am waiting for the lp reg rebuild kit and had some time, I decided to take apart the valve and see how bad it was.
It was bad!
I cleaned it out with brake clean, wiped off the diaphragms with paper towel, gently blew it dry, assembled, installed, and tested.
Generator runs much smoother and will take the a/c load without stalling.
However, the a/c is not right yet.
While running on shore I hear a compressor come on and turn off pretty quickly.
While on generator the generator will bog (load down) pretty hard but not stall as before.
I call this a partial win.
I've ordered capacitors for the a/c compressors and they should be in soon.
I did try switching the caps between the two compressors but the problem still persists.
I may have a bad compressor.
I can get by on one for now if I have to. I'll just have to figure out the wiring, in order to switch which one runs on 30amp service (comp1 I believe).
Everything on a coach is built around everything else, as you all know.
My next "upgrade" will be to install the Victron Quatro II with a display I purchased.
Thanks for the help!
Bruce F