Fish
Tree Freak
OK PHYSICS majors!!!!!
What is the boiling point of fuels/gasoline/gasahol??????
What is the boiling point of fuels/gasoline/gasahol??????
Stihl 362 Overheated Today, Boiling Fuel?
- Thread starter navistar82
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Fish
Tree Freak
But that would depend on the "pressure" in the tank, correct????
Fish
Tree Freak
So, opening the caps on these boiling tanks should have at least given the user a little burn/boo-boo????
Fish
Tree Freak
Let's discuss this, before getting too snooty....
Yes, I imagine that would influence it. The greater the atmospheric pressure above any liquid, the higher its boiling point and vise versa. Note that water boils at only 180 F or so at high altitude. And, pressure cookers cook food faster.
Fish
Tree Freak
Well, I have cut wood with a few old xl-12s, the pistons were scarred all to hell, but they still cut like champs....
On a hot afternoon, they would shut down, and we would have to wait until they cooled, that gas back then boiled good too!
On a hot afternoon, they would shut down, and we would have to wait until they cooled, that gas back then boiled good too!
Warped5
WingNut
I try to learn something new every day ...
I like Lone Wolf's idea of using two saws and have done this myself. But that doesn't explain why I never have to switch off to another saw when I'm using my Mac 10-10 .... ? Using the same fuel mix ...
I'll add to the discussion .... a week ago after some stumping, I went to refill the bar oil and vapor came out of that tank. THAT'S hot ..... :msp_scared:
I like Lone Wolf's idea of using two saws and have done this myself. But that doesn't explain why I never have to switch off to another saw when I'm using my Mac 10-10 .... ? Using the same fuel mix ...
I'll add to the discussion .... a week ago after some stumping, I went to refill the bar oil and vapor came out of that tank. THAT'S hot ..... :msp_scared:
Fish
Tree Freak
Yes, a cumbustion engine held in your hands in 100 degree weather is likely to be/get real hot, but is the fuel really boiling? What temp?
Coming off what pressure????
Coming off what pressure????
Hedgerow
HACK
The emptier a tank gets, the less fluid is in the tank, therefore more air... Air expands with heat creating pressure...
Fluid? Not so much... Yes cutting in this heat is just inconvenient at times, but that's why I take 2 saws. My larger saws seem to have less issues with the heat also... I run them a bit fat and they get some idle time which seems to help, but I got a 520 makita that just don't like 100 degree days... But it's gonna get used to it or die tryin!!!
Is the 10-10 fuel tank design different than your other saws?
Fish
Tree Freak
What, you own a Mammary bar?????
Hedgerow
HACK
Warped5
WingNut
My 520 has an attitude when it gets hot too! LOL
Where most of the more modern saws have their fuel near the ccase, the 10-10 is mounted higher up and forward of the block. There's also a bit of an air gap in there ...
Hedgerow
HACK
Stihl 076... Boilin'-est mutha I've ever run...Wasn't even that hot that day...
Couldn't have been more than 103...:msp_wink:
[video=youtube;cSrCmLZ0Wp0]http://www.youtube.com/watch?v=cSrCmLZ0Wp0&list=UUfB03KVhJRBISPufMa8F7GA&index=8&feature=plcp[/video]
Couldn't have been more than 103...:msp_wink:
[video=youtube;cSrCmLZ0Wp0]http://www.youtube.com/watch?v=cSrCmLZ0Wp0&list=UUfB03KVhJRBISPufMa8F7GA&index=8&feature=plcp[/video]
Fish
Tree Freak
I need to remember to keep a thermometer with me, I am real curious about the temp of the "boiling" fuel....
Maybe it has just become carbonated.......
Maybe it has just become carbonated.......
Vibes
Addicted to ArboristSite
When I'm stumping on a hot day, and someone is with me, I'll have them feed air to the saw with a handheld blower. Sometimes it can be a little dusty but it does make the saw run smoother. Also, even in cold weather, I let the engine idle down for a minute or so after its been run hard. I do that with all my OPE that still has a throttle. My thinking is its like the cool down lap that you see at the race tracks. Thats one reason I never liked these new push mowers that don't have a throttle. You can't let them cool down.
My Olypic 264 boils fuel worse than that Stihl in the video above. You can hear it bubbling inside the saw when shut off.
My Olypic 264 boils fuel worse than that Stihl in the video above. You can hear it bubbling inside the saw when shut off.
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hangfirew8
ArboristSite Operative
I did a little googling...
Ethanol boils at 78.37C (173.1° F), octane (pure) at 125C (257° F) (there's n-Octane and iso-Octane and they differ a bit, so I think this value is something of an average.) For MTBE (on its way out) it's 55.2C (131 °F). TAME is 86.3C (187 °F), and so on.
Cool idea (pun intended). Even warm air can cool an engine if there's enough of it. Lately I've switched from using compressed air to my Stihl blower for cleaning off my riding mower before storing it for next week, and I was thinking about what supercharged air cooling might do for engine life... probably less than using Mobil 1. Nothing beats the compressor for blowing out a chainsaw, though.
Your 4-stroke B&S engine type OPE cool-down time is effective because the unloaded motor governor applies less throttle then when loaded. Less fuel, less heat. However those engines are made to run (and cool themselves) at 3600 RPM, when you run it slower it has moving less air over the fins. If all is working well, it will cool itself faster if left at 3600 and unloaded.
Since I'm sure you keep your motor properly maintained and lubricated, it probably doesn't matter that much. A few folks (haven't found any here) think that running loaded (cutting grass, self-propelled) at partial throttle is a good idea. It's not. Lots of heat and not enough air movement.
HF
Ethanol boils at 78.37C (173.1° F), octane (pure) at 125C (257° F) (there's n-Octane and iso-Octane and they differ a bit, so I think this value is something of an average.) For MTBE (on its way out) it's 55.2C (131 °F). TAME is 86.3C (187 °F), and so on.
Cool idea (pun intended). Even warm air can cool an engine if there's enough of it. Lately I've switched from using compressed air to my Stihl blower for cleaning off my riding mower before storing it for next week, and I was thinking about what supercharged air cooling might do for engine life... probably less than using Mobil 1. Nothing beats the compressor for blowing out a chainsaw, though.
Your 4-stroke B&S engine type OPE cool-down time is effective because the unloaded motor governor applies less throttle then when loaded. Less fuel, less heat. However those engines are made to run (and cool themselves) at 3600 RPM, when you run it slower it has moving less air over the fins. If all is working well, it will cool itself faster if left at 3600 and unloaded.
Since I'm sure you keep your motor properly maintained and lubricated, it probably doesn't matter that much. A few folks (haven't found any here) think that running loaded (cutting grass, self-propelled) at partial throttle is a good idea. It's not. Lots of heat and not enough air movement.
HF
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themaddhatter
ArboristSite Operative
You got a few more things to throw in there:
- Lowest MW stuff in gasoline will evaporate first. This is usually butane (like a bic lighter butane). And the bp is just below the FREEZING point of water (bp is ~ 30 F). They put it in winter blend gas because it is cheap, but in the summer it leads to more evaporation, so they have little to none in the summer. But, there will be other compounds in there as well. Remember, gasoline is not pure octane. It is a mixture of all different linear and aromatic hydrocarbons. Octane rating is simply used to establish a comparative scale to base things on. There is probably a few things in there which will have to boil off before the EtOH starts cooking.
- Tank pressure impacts boiling point. Remember back in school days, ideal gas law PV=nRT. If volume unchanged, pressure goes up with temperature. You crack a tank, you create a pressure drop which CAN get boiling going. In the case of the OP, when he opened the tank and it came flying out, he was probably on the hairy edge of boiling, and the pressure drop pushed it over the hump.
Been messing with my 420 all week dealing with hot start issues. Tune, tune, tune, and it would not behave. The last two days have been below 90 F, and the hot start & bogging acceleration have disappeared. Now I know to get up early and get my cutting done before lunch.
I had the same problem last year, i found that the tank vent in the tank cap eas pluged in the cap with dirt. In the old days this was called a vacume lock which would over presure the tank and seem to spray or boil the gas out of the tank. So get a small wire to clean out the vent hole or buy a new cap.
D&B Mack
Sawin Wit It!
:agree2:
If your tank quits "breathing", you can get the boiling point down to the low 100's in the tank. And, on a hot day, it won't take much for your saw to get up to this temp. However, when you are boiling any liquid by use of a lower pressure, once the pressure is equalized, the boiling will instantly stop (assuming the temp. is not high enough to boil at the atmospheric pressure).
