4140 gas boiling in tank

petertay

Member
Tractor is a heavy duty Industrial. 172 gas engine. New to me. When the engine is at working temp but not overheated, the gas is boiling in the tank.
It does not have original tank cap, but the one I have is vented. The tank has a solid heat shield under it, protecting is from the manifold, and the
muffler has a flexible, shiny insulation cover strapped over it.

I tried searching the archives, but Firefox browser says the search page is not safe to use. .?

Thanks for the help. ?Peter
 
gasoline is composed of many compounds and some begin to boil as low as 173f, so what you see is common.
 
You say it is common? Wow, back in the day when many people had cigarettes hanging from their lips, and with the cap being vented, didn?t that cause
a few booms?
 
(quoted from post at 20:07:07 05/14/20) You say it is common? Wow, back in the day when many people had cigarettes hanging from their lips, and with the cap being vented, didn?t that cause
a few booms?
ctually, the explosive range of air/fuel ratio is really quite narrow (except for acetylene & another or two) , or else we would all be blown up by now.
 
(quoted from post at 22:00:04 05/14/20)
(quoted from post at 20:07:07 05/14/20) You say it is common? Wow, back in the day when many people had cigarettes hanging from their lips, and with the cap being vented, didn?t that cause
a few booms?
ctually, the explosive range of air/fuel ratio is really quite narrow (except for acetylene & another or two) , or else we would all be blown up by now.

Add to that the fact that gasoline back in the day didn't have as many additives that boil at lower temperatures, like ethanol, and it wasn't as much of an issue back then.
 
Stupid suggestion: Try checking the engine timing first, then if that doesn't help, replace the fan belt.
 

Also check the air path through the area. As has been said this is not uncommon but usually only under a sustained heavy load in hot weather.
 
Verify that the muffler heat shield and fan shroud are both in place.

Also verify the ignition timing and proper operation of the centrifugal advance mechanism.

Avoid gasoline with ethanol.

Dean
 
Thank you for the replies and suggestions. The engine starts within seconds and runs so well, I would not have suspected the timing, but as it is new to me, I will do so. Meanwhile, it good to know that boiling gas happens, that I?m not about to blow myself up when I get on it. ?Peter
 

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