Choke on shutting down gas engine?

[sheepfarmer]

Idle curiosity here, but there is a guy that works for me occasionally, of the general sort that could break an anvil so he doesn't have a lot of credibility, and every time he goes to stop the old Ingersoll he shoves the choke lever all the way on. I have asked him why he did that, and the only answer I got was that he thought he was supposed to. Once it is warmed up it starts fine with no choke, so I have said don't do that in case he flooded it, but he does it anyway, so I figure it must be an ingrained habit.

So to get to my question, is there some other type of equipment that it is necessary to choke before you shut it down that he could have learned on first? I learned about chokes on cars and trucks, and you do NOT want to forget to unchoke them, but no experience with other types of mowers etc.

 

[JorisFRST]

My understanding is that a rich tuned engine would turn itself off when choked.

why you would want to do that on any engine when you can just turn off the spark is beyond me, can't be very good for the engine to have it splutter to death before killing the spark.

It won't be that bad as it's only going to be a very short time in this example, but you don't want to run an engine overly rich (choked) for an extended period of time.

Maybe he's used to diesel tractors and thinks it's the decomp ??? Weird ...

 

[Greenhead]

I'm trying my best to refrain from saying what I'm thinking.
The best I can print is "You can't fix stupid"...

 

[Tooljunkie]

Nope. Its just dumb. Some engines-kawasaki for one had plastic timing gears and if not idled for a minute before shutdown could backfifire And shear off the teeth on the cam gear, flooding to shut down will cool plug and prevent the backfire. Maybe. Done frequently will dilute the oil.

 

[geoff]

I would not think it a good way to shut off a four stroke, it will wash the bore of oil, leaving it unprotected on start up.
Not so bad on a two stroke, but why not just use the spark cut off...

 

[D2Cat]

Remember the story about the young girl who asked her mom, while fixing Thanksgiving dinner, why she always cut the ham in half when she put it in the pan. Mom said, I don't know, but mom always did. Daughter was baffled, so she went into the parlor and asked Grandma why she cut the ham in half before putting in in her pan.

Grandma's answer was, "Because that's is size of pan I had."

Humans do some thing without though or reason. After enough time passes to re-evaluate why something is continually done without merit, they're referred to as: dumb dumb's, doto's, fools, ignorant, and other adjectives.

That fellow's Grandma probably cut the ham in half, and he didn't care why, he just kept doing it. Same with the choke on every engine he's ever ran!

I was thinking of an analogy. If your helper uses an alarm to get him up in the morning (that's his choke to get started)....does he use an alarm when he go to sleep...to get him to quit working?

 

[sheepfarmer]

Hmm ok I think I'll go with you can't fix stupid. Asking politely, repeatedly explaining the reason, telling, and getting downright nasty on various issues doesnt usually work. I just wanted to make sure I wasn't the one that was ignorant. When it comes to equipment I generally try to decide how much it is going to cost to fix it before I let him use it. Needless to say hell will freeze over before I let him near the tractors. He works hard, and can lift stuff I can't, but I have to work right along side him to keep stuff on track. I think he is honest, but he just doesn't have any feel for mechanical things. Thanks guys!

 

[twomany]

In cold weather, a choke shutdown can go a long way towards a quick startup next time.

The Kohler engine in the Bolens is fuel greedy. A "wet" shutdown almost assures a first turn fire even on the coldest days. I usually don't apply choke until the engine is spinning when the temps hoover near zero F. If the engine fires on shut down fuel, I know it is warm enough not to flood when the choke is pulled.

Works for me...
over twenty years ;-)

 

[sheepfarmer]

Ah so,twomany, maybe this is where it comes from! It does get cold in MI, and he is applying something he saw on snowblowers to my lawnmower in 90 degree weather.

 

[Vacula]

I agree that one must always idle the engine down for a minute minimum after a long run time to cool it before shutdown but choking a gasoline small engine to death, (stall), is not a bad thing. The Kohler K series 10 horse on the Wheelhorse 310's made in the 1980s would create a huge backfire if you didn't choke it to stall to shut it down or if you didn't crank the throttle up half way after you kill the ignition. (Both do the same thing). Might you go through plugs more? Maybe. But I still own my 310-8 Speed Wheelhorse and have for decades and this is how I shut it down. Cheaper than buying air filters after a good bang!
Now that doesn't answer the question on why he just doesn't shut the ignition down. Again, you can't fix a shallow gene pool creation once they get out into the wild!

 

[Tooljunkie]

Friend had a green and yellow 755 compact tractor. Yard maintenance guy, also a small engine repairman (self-proclaimed) used to come up to the shop, tractor wide open and flip off the key. Horrible sounds. Made a mess of that machine in one summer. Wide open for mowing, not pto speed. Mower was trashed engine was falling out muffler broke off. That thing was 15 years old and never had a single problem until that summer.

 

[Greenhead]

https://www.youtube.com/watch?v=CwGrC0KicSo

 

[Grouse Feathers]

Back in the old days before everything was interlocked (in an attempt to fix stupid) you used to shutdown a small gas engine by bending a little metal tap over to short out the top of the spark plug. Sometimes depending on the design of the engine and implement it was easier, or quicker or safer to reach the choke to stop the engine. The only thing I now have to choke to stop is one of my chainsaws with a bad stop switch. Its a husky and always starts back up with one pull so no problem with flooding.

 

[sheepfarmer]

https://www.youtube.com/watch?v=CwGrC0KicSo

Yup! That's him

 

[twomany]

Back in the old days before everything was interlocked (in an attempt to fix stupid) you used to shutdown a small gas engine by bending a little metal tap over to short out the top of the spark plug. Sometimes depending on the design of the engine and implement it was easier, or quicker or safer to reach the choke to stop the engine. The only thing I now have to choke to stop is one of my chainsaws with a bad stop switch. Its a husky and always starts back up with one pull so no problem with flooding.

Pushing over the spark short bar doesn't do much for multi cylinder engines.

 

[sheepfarmer]

Back in the old days before everything was interlocked (in an attempt to fix stupid) you used to shutdown a small gas engine by bending a little metal tap over to short out the top of the spark plug. Sometimes depending on the design of the engine and implement it was easier, or quicker or safer to reach the choke to stop the engine. The only thing I now have to choke to stop is one of my chainsaws with a bad stop switch. Its a husky and always starts back up with one pull so no problem with flooding.

Omg I have a dim memory of shutting down a lawn mower with a tab like that, must have been when I was a kid and assigned the task of cutting the grass.

 

[dandeman]

I do use a sequence of pulling the choke as part of the shut down procedure for old Ford 4000 gas tractor when it is going to be stored and not used for a long time..

Before stopping the engine I shut off the fuel supply valve to the carburetor.. and then run the engine at a high speed to burn the remaining gas out of the carburetor float bowl and passages in the carburetor. Just as the engine begins to miss from running out of gas I pull the choke full on hopefully so manifold vaccum from the engine still turning will help suck any residual gasoline out of fuel bowl & passages inside the carburetor so the engine goes into storage with no gasoline left in the carburetor.

Since I've been doing this (over several decades) I've had no more problems with carburetor gum up during long storage periods.

You can read about a somewhat similar practice (with many stated reasons for doing so) with piston aviation engines (run the engine up off idle to a high rpm then putting the fuel (tank) selector valve to the off position, putting the mixture control to the idle cutoff position, to cut fuel to stop the engine and finally turning the magnetos to the off position). Reasons I've read range from ensuring no residual fuel remaining in a cylinder or no residual fuel in the carburetor, to trying to ensure on dry sump engines, as little oil as possible is left in the dry sump.. Both of these are important factors on radial engines where bottom cylinders can hydro-lock from excessive oil leaking during storage down through the piston rings into the combustion chamber. Typically they have to be hand propped before starting to ensure no cylinder is hydrolocked with oil. And if hand propping, for safety reasons you don't want the possibility of any gasoline in the carburetor or cylinder, even though you know the the mags are off.

So far as the backfiring mentioned above, the larger P&W Cyclone multi-row radial engines especially, are primed and started with pretty excessively rich fuel mixture to prevent a backfire. Reason being the intake manifolding of these engine are rather complex, made of aluminum tubing and clamped joints.. A backfire can be strong enough to blow the manifold piping apart and start an engine fire.

http://www.vansairforce.com/community/archive/index.php?t-48293.html

 

[twomany]

I do use a sequence of pulling the choke as part of the shut down procedure for old Ford 4000 gas tractor when it is going to be stored and not used for a long time..

Before stopping the engine I shut off the fuel supply valve to the carburetor.. and then run the engine at a high speed to burn the remaining gas out of the carburetor float bowl and passages in the carburetor. Just as the engine begins to miss from running out of gas I pull the choke full on hopefully so manifold vaccum from the engine still turning will help suck any residual gasoline out of fuel bowl & passages inside the carburetor so the engine goes into storage with no gasoline left in the carburetor.

Since I've been doing this (over several decades) I've had no more problems with carburetor gum up during long storage periods.

You can read about a somewhat similar practice (with many stated reasons for doing so) with piston aviation engines (run the engine up off idle to a high rpm then putting the fuel (tank) selector valve to the off position, putting the mixture control to the idle cutoff position, to cut fuel to stop the engine and finally turning the magnetos to the off position). Reasons I've read range from ensuring no residual fuel remaining in a cylinder or no residual fuel in the carburetor, to trying to ensure on dry sump engines, as little oil as possible is left in the dry sump.. Both of these are important factors on radial engines where bottom cylinders can hydro-lock from excessive oil leaking during storage down through the piston rings into the combustion chamber. Typically they have to be hand propped before starting to ensure no cylinder is hydrolocked with oil. And if hand propping, for safety reasons you don't want the possibility of any gasoline in the carburetor or cylinder, even though you know the the mags are off.

So far as the backfiring mentioned above, the larger P&W Cyclone multi-row radial engines especially, are primed and started with pretty excessively rich fuel mixture to prevent a backfire. Reason being the intake manifolding of these engine are rather complex, made of aluminum tubing and clamped joints.. A backfire can be strong enough to blow the manifold piping apart and start an engine fire.

http://www.vansairforce.com/community/archive/index.php?t-48293.html

When I shut down the Fordson E27n (gas) after pulling it under cover in the lower side of the bank barn, I just shut off the fuel tap and walk away.

It takes about a minute to run the fuel bowl dry. By that time, I'm on the porch ready to go inside to wash up.