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Thread: Propane generator

  1. #1
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    Default Propane generator

    Good morning,

    I was reading that running my little champion dual fuel 8500 watt generator exclusively on propane may cause some issues with the valves due to lack of lubrication. While I know what a valve is/does, that’s about it.

    I have no idea whether this is an actual concern on a cheapish little generator like this.

    I’ll never run it on gasoline. It’s stored indoors and I don’t want the stink. And running it on propane makes a super pleasant worksite.

    Is this valve lube kit a good idea or just snake oil?

    https://www.flashlube.com/images/sto...t-brochure.pdf

    And is there anything else I could do to extend the unit’s life other than regular maintenance stuff?

    Thanks

  2. #2
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    Default Re: Propane generator

    We’ve got a 22KW generator for the house. Runs on propane. No issues. It is amazing how clean the oil stays as opposed a gasoline powered engine.
    Fight Entropy, build a wooden boat!

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    Default Re: Propane generator

    Can you share what you were reading about the lubrication concerns? Instinctively, I agree with your suspicion that it's an unworthy upgrade on a cheapish portable unit.
    "Visionary" is he who in every egg sees a carbonara.

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    Default Re: Propane generator


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    Default Re: Propane generator

    fta -

    The intake valves in an engine become very hot during operation. The only time they have to dissipate that heat is when the valve closes and is seated in the head. During this time the heat from the valve is transferred into the head and from there transferred into the cooling system of the engine. Since these gaseous alternative fuels don’t offer an evaporative cooling and burn hotter than gasoline; the intake valve overheats. Once the intake valve overheats, when it is seated in the head, that heat is so great that it begins to melt the aluminum of the head at the valve seat and to “recess” into the head. Over time this causes leaks at the seat which in turn causes uneven cooling of the valve and ultimately causes the valve to melt at the leak. This process is commonly referred to by mechanics as burning a valve.
    gobbledygook

    there is (or can be) an overheating issue w/ propane, but whoever wrote that was flat out clueless. Guessing your genset is aircooled.. make sure it has plenty of airflow.

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    Default Re: Propane generator

    "Gobbledygook" is rather kind imho.

    I don't know if small-engine manufacturers bother to install steel valve seats in their aluminum heads, but even that is irrelevant to this author's nonsensical argument that introducing an evaporative-cooling element to the intake valve will prevent an overheat condition which is far more likely to occur on the exhaust valve.
    "Visionary" is he who in every egg sees a carbonara.

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    Default Re: Propane generator

    The manufacturer of the engine could answer better than we could, but the intake valve is cooled somewhat by the cooler air flowing past it into the cylinder which the writer above does not want to mention. The expanding propane going from tank pressure into the vacuum pulled by the cylinder would also absorb heat.

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    Default Re: Propane generator

    Bluedog's generator manufacturer should be able to tell him whether there are valve seats, and if so what they are made of. The manufacturer might even provide info on engine life with propane vs gasoline. If it was me I wouldn't worry about it, since I probably wouldn't be running long hours on it.

    I don't understand the "gobbledygook" comments here though. For many years now it has been well known that intake valves run cooler with liquid fuels rather than gaseous fuels. Whether this is significant for Bluedog's generator life remains to be seen.

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    Default Re: Propane generator

    Quote Originally Posted by Dave Wright View Post
    Bluedog's generator manufacturer should be able to tell him whether there are valve seats, and if so what they are made of. The manufacturer might even provide info on engine life with propane vs gasoline. If it was me I wouldn't worry about it, since I probably wouldn't be running long hours on it.

    I don't understand the "gobbledygook" comments here though. For many years now it has been well known that intake valves run cooler with liquid fuels rather than gaseous fuels. Whether this is significant for Bluedog's generator life remains to be seen.
    Most modern engines run direct injection. The intake valves never see fuel going past them.
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    Default Re: Propane generator

    Quote Originally Posted by Art Haberland View Post
    Most modern engines run direct injection. The intake valves never see fuel going past them.
    Is that the case for Bluedog's generator, the engine under discussion here????

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    Default Re: Propane generator

    Quote Originally Posted by Dave Wright View Post
    I don't understand the "gobbledygook" comments here though. For many years now it has been well known that intake valves run cooler with liquid fuels rather than gaseous fuels. Whether this is significant for Bluedog's generator life remains to be seen.
    it's gobbledygook because the exhaust valve will see more heat than (and fail before) the intake valve, regardless of whether the fuel is liquid or gaseous.
    "Visionary" is he who in every egg sees a carbonara.

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    Default Re: Propane generator

    Quote Originally Posted by Figment View Post
    it's gobbledygook because the exhaust valve will see more heat than (and fail before) the intake valve, regardless of whether the fuel is liquid or gaseous.
    Maybe more than anything else this thread demonstrates the problem with written communication on the internet and how folks can create confusion.

    Durnik said "gobbledygook" to a quoted paragraph specifically addressing INTAKE VALVES for gaseous vs liquid fuels. Compare that paragraph to an abstract by :

    Jim Cowart and Wai Cheng of MIT (1999)

    Intake Valve Thermal Behavior During Steady-State and Transient Engine Operation
    Abstract

    "Intake valve thermal behavior was observed across a wide range of operating conditions while running an engine on both propane and gasoline. Compared to the gaseous fuel, the liquid fuel operation has cooler valve temperatures (~50-100C difference) and there is significant temperature gradient across the valve surface due to liquid fuel impinging on the front quadrant of the valve. The valve warm-up time is largely determined by the effective thermal inertia of the valve (~valve body plus 1/3 of stem mass) and the thermal resistance to the seat. The valve is heated up by the combustion chamber; the dominant cooling paths are through the seat contact and the liquid fuel evaporation. Just after starting, very little fuel evaporates from the cold valve until there is a substantial increase in valve temperature in a period of approximately 10-20 seconds."


    Seems to me that this confirms that the quoted paragraph is not gobbledygook.

    But wait, Figment says that the quoted paragraph is gobbledygook because it addresses intake valves and not exhaust valves.

    Figment is correct, exhaust valves run hotter than intake valves and fail more frequently so the paragraph is IRRELEVANT to Bluedog's case. I say irrelevant, because it is still informative rather than gobbledygook.

    So what decent info can we leave Bluedog with? I would say that we can tell him that his propane operated device will probably run hotter and at higher pressures on propane as opposed to gasoline. He can read about that here:

    https://www.researchgate.net/publication/263874565_Review_of_fuels_for_internal_combustion_ engines_in_the_aspect_of_economy_performance_envir onment_and_sustainability

    Is any of this significant to the operation of his generator? Probably not.

    Bluedog, run the goddam thing if and when you choose, don't worry about it, and spend less time in the bilge.





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    Default Re: Propane generator

    Tom's generator doesn't use direct injection and if info online is correct, is probably a Chinese copy of a Honda engine. That said, Honda might also get their engines built in China and there is no telling if valve seats are the same or even if Honda uses hardened intake valve seats. But new heads are available if the seats did ever wear down enough to affect the engine performance.

    Question: How does an engine with splash lubrication and overhead valves get oil to the heads? Somehow using crankcase vacuum?

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    Default Re: Propane generator

    in many such engines, the pushrods are hollow. The linear movement of the lifters provides a pumping effect which sends oil up the pushrods, and then scatter-effect from the rocker arm.
    "Visionary" is he who in every egg sees a carbonara.

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    Default Re: Propane generator

    Somehow I know we would get to pushrods.

    Thanks all!

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    Default Re: Propane generator

    I’m thinking of getting the next one smaller than that in dual fuel If it isn’t used every few months remember to put a charger on the battery. They come w cheap batteries and sitting for a long time you end up w a dead battery. Much rather have a propane tank sitting for 8 months than a gas tank.

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    Default Re: Propane generator

    Also, there’s a little lighted switch to power the starter. It will drain the battery over months. I think, but have not verified, that it has to be on for the genny to charge the battery.

    It’s been a champ. Propane and full synth that comes out as clean as it goes in.

    7D905250-85EE-4C6D-AF98-4C05459A503E.jpg

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    Default Re: Propane generator

    Quote Originally Posted by Figment View Post
    it's gobbledygook because the exhaust valve will see more heat than (and fail before) the intake valve, regardless of whether the fuel is liquid or gaseous.
    exactly.. which further prompted my 'they are clueless' comment.

  20. #20
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    Default Re: Propane generator

    They did say that exhaust valves and their seats were hardened.

    Like the removal of lead from gasoline, this issue is easily fixed by installing hardened intake valves and hardened intake valve seats. This is the exact fix that was done by the OEM’s on the exhaust valves with the implementation of unleaded gasoline.
    I have more trouble with this statement.
    The only time they have to dissipate that heat is when the valve closes and is seated in the head.
    Intake valves can dissipate heat as cooler outside air and propane flow into the cylinder.

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    Default Re: Propane generator

    Quote Originally Posted by Jimmy W View Post

    Intake valves can dissipate heat as cooler outside air and propane flow into the cylinder.
    Sure, some cooling must take place.

    I imagine someone has placed sensors in a four stroke engine and could tell you how much cooling occurs for propane versus gasoline. Think of how long an intake valve is open on a four stroke engine - only on the intake stroke. So you know the valve is closed on the compression, combustion, and exhaust stroke. Cooling takes place by heat transfer from the valve to the valve seats no matter what the fuel.

    But with propane fuel, cooling propane flow would only cool on that the opening stroke. In contrast a gasoline vapor mix would cool by "flow" on the intake stroke, but also by evaporation for a longer period of time, because the fuel vapor mix coats the back side of the valve and the heat transfer process occurs while the valve is closed as well as open. I can only guess that the gasoline vapor flow / evaporation cooling is very much greater than cooling due to propane flow.

    Maybe someone here can find a study that quantifies the two fuel cases, and we can see how significant the propane flow cooling is.

  22. #22
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    Default Re: Propane generator

    propane has less btu's than gasoline
    If the manufacturer set it up to run on propane I would not give it a second thought.

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    Default Re: Propane generator

    Wittering on about valve cooling, and only mentioned the intake!

    That's not where you get problems, anyone ever seen a sodium cooled intake valve?
    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

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    Default Re: Propane generator

    Well cars seem to run on it just fine, we put tens of thousands of km on the old ford 2 litre (same as the Pinto motor) we had on gas, no problems - and I bet a car engine works harder over its lifetime than a standby genny. Unleaded petrol would kill them quite fast though, without either the squirt in additive, or getting hardened valve seat inserts.

    FWIW, the offshore gas rig off the coast of Sarawak that I spent a week on just as covid was kicking off, ran the big-ass gensets (about a MW each) off gas straight out of the well head. They pretty much run 24/7/365 to power the pipline compressor.

    Pete
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    Default Re: Propane generator

    Quote Originally Posted by Canoeyawl View Post
    propane has less btu's than gasoline
    If the manufacturer set it up to run on propane I would not give it a second thought.
    It also is also much less prone to detonation than gasoline - you could lean it out in the car to the point that it was impossible to exceed the 100km/hr speed limit at wide open throttle, and it still wouldn't ping, even going up hills. Probably not helpful in a genny, but it is really hard to destroy an engine running on this stuff.

    Pete
    The Ignore feature, lowering blood pressure since 1862. Ahhhhhhh.

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    Default Re: Propane generator

    Remember that this is a Chinese copy of a Honda. Since Hondas run at least 20x as long as any Briggs & Stratton or Tecumseh, this'll probably run 10x as long at least. So - he's way ahead of any American made crap.

    I'm with Jake - run it.
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    Default Re: Propane generator

    Quote Originally Posted by bluedog225 View Post
    Also, there’s a little lighted switch to power the starter. It will drain the battery over months. I think, but have not verified, that it has to be on for the genny to charge the battery.
    This is the stuff that drives me nuts. Mine does the same. It has this little port for a trickle-charger to maintain the battery, but who's going to dedicate a whole outlet to that?

    Also... that little fuel shutoff valve? POS
    In our most recent power outage, the gen would fire-but-not-run. I worked on it for an hour confirming spark and compression and defeating the oil pressure safety switch etc, and then the power came back on.
    The next day I spent ANOTHER HOUR checking every little thing to determine that the bracket behind that panel wasn't securely holding the valve, turning the handle didn't actually open the valve it turned the valve in the housing.

    and yes I "exercise" this thing every few months whether we need it or not.
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    Default Re: Propane generator

    Quote Originally Posted by P.I. Stazzer-Newt View Post
    Wittering on about valve cooling, and only mentioned the intake!

    That's not where you get problems, anyone ever seen a sodium cooled intake valve?
    A couple of people read the whole article that Bluedog referenced:

    https://www.transtechenergy.com/LPG-...alve-recession

    Both intake and exhaust valves were discussed. But some people never read the article, instead commenting on only one paragraph, the paragraph that Durnik posted.

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    Default Re: Propane generator

    Quote Originally Posted by P.I. Stazzer-Newt View Post
    Wittering on about valve cooling, and only mentioned the intake!

    That's not where you get problems, anyone ever seen a sodium cooled intake valve?
    Oh yeah!
    Sodium filled, you can shake them and hear it in the stem (when they are new)
    Old ones are problematic, replace them, they break. And they are expensive!

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    Default Re: Propane generator

    Quote Originally Posted by Canoeyawl View Post
    Oh yeah!
    Sodium filled, you can shake them and hear it in the stem (when they are new)
    Old ones are problematic, replace them, they break. And they are expensive!
    Mercedes diesels - eye-watering prices - even back when they were current
    "If it ain't broke, you're not trying." - Red Green

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    Default Re: Propane generator

    Quote Originally Posted by bluedog225 View Post
    Good morning,

    I was reading that running my little champion dual fuel 8500 watt generator exclusively on propane may cause some issues with the valves due to lack of lubrication. While I know what a valve is/does, that’s about it.

    I have no idea whether this is an actual concern on a cheapish little generator like this.

    I’ll never run it on gasoline. It’s stored indoors and I don’t want the stink. And running it on propane makes a super pleasant worksite.

    Is this valve lube kit a good idea or just snake oil?

    https://www.flashlube.com/images/sto...t-brochure.pdf

    And is there anything else I could do to extend the unit’s life other than regular maintenance stuff?

    Thanks
    Snake oil - a pointless treatment for a non existent problem.

    Do the maintenance - by the book.
    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

  32. #32
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    Default Re: Propane generator

    Quote Originally Posted by Garret View Post
    Mercedes diesels - eye-watering prices - even back when they were current

    I remember about $25-30 each in 1980...
    (an ordinary valve was "maybe" $5)
    For truck service I used to buy them by the specific stem/head dia and cut them down on both ends, heads and locks, so that probably doubled the cost at least.
    (Fwiw, they are about $60 each today, engine specific)
    On a race bike we tried drilling valves hollow from the head into the stem and tig weld up the hole to make them lighter. Which didn't help much in rpm's, but it did help valve guide wear by letting the valve flex a bit more from the rocker arm. We gave it up afraid they would break in use, which is bad... really bad.

  33. #33
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    Default Re: Propane generator

    Quote Originally Posted by Canoeyawl View Post
    I remember about $25-30 each in 1980...
    (an ordinary valve was "maybe" $5)
    For truck service I used to buy them by the specific stem/head dia and cut them down on both ends, heads and locks, so that probably doubled the cost at least.
    (Fwiw, they are about $60 each today, engine specific)
    On a race bike we tried drilling valves hollow from the head into the stem and tig weld up the hole to make them lighter. Which didn't help much in rpm's, but it did help valve guide wear by letting the valve flex a bit more from the rocker arm. We gave it up afraid they would break in use, which is bad... really bad.

    OK - "eye watering" might've been a bit of hyperbole, but ~120 just for valves was brutal for someone making $7 an hour.
    "If it ain't broke, you're not trying." - Red Green

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    Default Re: Propane generator

    A couple of people read the whole article that Bluedog referenced:

    https://www.transtechenergy.com/LPG-...alve-recession

    Both intake and exhaust valves were discussed. But some people never read the article, instead commenting on only one paragraph, the paragraph that Durnik posted.
    Once a body sees obvious gobbledygook (and as Figment said, that was being rather kind) in a manual, not much reason to read a whole lot more. There's the story of a broke clock correct twice a day - but you can't tell when by looking at it. FWIW, more was also gobbledygook (& b.s.). As others noted, it's exhaust valves that are prone to burn. If an intake valve burns, there's something very wrong - adjusted too tight (& we trust Bluedog to not do that) or engine overheating, which is why I mentioned adequate air flow. When we used to install generators inside, we'd put two louvered vents across (or kittycorner to) them, one with a fan and both set to open when the gen fired up. Guaranteed Positive Air Flow! That's how all the gens I worked on in the military were set up too. As others said, it'll likely be fine, fire it up.

    an aside.. decades ago I was involved in writing tech manuals.. which were then sent thru marketing to 'make them understandable by users'.. and they would always come back bearing little relation to the equipment/reality.. just like this manual. So it goes!

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    Default Re: Propane generator

    Quote Originally Posted by Garret View Post
    OK - "eye watering" might've been a bit of hyperbole, but ~120 just for valves was brutal for someone making $7 an hour.
    Much worse for a V-8; damn near a weeks pay, only to bend them all in 12 or 13 seconds...

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