# ST-524 Engine No-Start



## badbmwbrad (Jul 30, 2019)

This problem has me stumped. The engine is a 5 HP Tecumseh. I can get the engine to fire once or twice (two power strokes max) then nothing. If I squirt starting fluid into the carburetor and/or if give the primer bulb a pump and try the pull-starter again then the same thing happens.

I removed the carburetor float bowl and sprayed choke cleaner into the brass tube located up above the float bowl bolt/adjustable main jet. The adjustable main jet has also been cleaned out. The idle mixture adjustment screw was removed and sprayed out.

The engine has an electric starter. During continuous engine cranking, I can see droplets of gasoline being discharged out of the carburetor and landing on the tire. I'm not sure if this is normal. I can't imagine the valve timing has changed. 

I've removed the flywheel blower housing and confirmed the Woodruff key is not sheared because the crankshaft keyway is aligned with the flywheel keyway. 

The sparkplug gap was too wide (0.035") and I reduced it to about 0.020" to get a hotter spark. 

The engine crankcase oil level was way too high and I changed oil and corrected the oil level.

The fuel I'm using is 100 octane low-lead aviation gas.

Any suggestions are welcome.


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## Oneacer (Jan 3, 2011)

A replacement carb is like 12-15 dollars .... That should put you back in buisiness.

Spark gap is 30 .... 20 is not good.

I'm not sure you want to be running a leaded aviation 100 octane fuel.

Gas leaking from the carburetor is not normal.

Oil way overfilled many times is gas in the oil, hence a carb issue. Running it in that manner will toast your engine.


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## Jackmels (Feb 18, 2013)

Ignition Points need Replaced or Cleaned.


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## orangputeh (Nov 24, 2016)

gas is leaking from carb to crankcase. bad float or needle seat. replace carb. cheap

then change oil.

then gap plug to factory specs. refer to owners manual.

also check points as mentioned but that other stuff first.


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## carguy20 (Feb 8, 2021)

Change the gap on that plug to the proper gap, or better yet put a new plug in it with a proper gap.

I just recently changed the plug in my mower because it would cut out after about 10 minutes of use, then fire up again after an hour to cool off. The plug was bad, and a new plug was the fix for it.

I would also ditch the aviation gas, if you put 93 octane pump gas, it should run just fine.


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## Tony-chicago (Feb 10, 2021)

As above. New carb or fix, if possible, needle seat etc. It has ruined the oil and possibly caused a lot of wear on engine. Do points etc. Or go electronic if possible. New plug of course.

Scratch fixing carb, go new. If time permits maybe you can get all the parts fixed on carb, but it is probably more than just the float, and for sure way more effort.


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## badbmwbrad (Jul 30, 2019)

Thanks for the suggestions. The original oil filler cap had no dipstick attached. I discovered the over-filled oil level when a dipstick was installed. The high oil level was corrected during the oil change. 

I'll swap the fuel from avgas to pump gas. 

Yesterday I was so close to the ignition contact breaker points (flywheel fully exposed and nut removed) but stopped further disassembly when I determined the flywheel key had not sheared. 

I have no idea whether the fuel spray coming out of the carburetor is part of the problem. I'll work to verify the intake manifold, exhaust pipe and muffler are cleared of any mouse nesting.


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## Tony-chicago (Feb 10, 2021)

Yes. True there could be other issues that are effecting the carb. Let us know.


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## davepb (Mar 13, 2021)

A model number would help. If it has points you will need to set the timing also, or you will have hard starting issues or bad kick backs when trying to start it.


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## Oneacer (Jan 3, 2011)

If that engine has points, just abandon them, and put in electronic ignition.


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## T. L. Kott (Jul 14, 2021)

badbmwbrad said:


> This problem has me stumped. The engine is a 5 HP Tecumseh. I can get the engine to fire once or twice (two power strokes max) then nothing. If I squirt starting fluid into the carburetor and/or if give the primer bulb a pump and try the pull-starter again then the same thing happens.
> 
> I removed the carburetor float bowl and sprayed choke cleaner into the brass tube located up above the float bowl bolt/adjustable main jet. The adjustable main jet has also been cleaned out. The idle mixture adjustment screw was removed and sprayed out.
> 
> ...


90% of all small engine problems are associated with fuel...


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## JLawrence08648 (Jan 15, 2017)

The first electronic ignition was Atom in the 80s, it was great. Always worked. The patent expired and then Nova II, now Mega Fire. I still have some Atoms, have also used Nova II.

You cut the wire going to the points from the ignition coil, twist in, ground the other end from the electronic module.


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## JLawrence08648 (Jan 15, 2017)

T. L. Kott said:


> 90% of all small engine problems are associated with fuel...


Almost agree, I think it's even higher! Lol, but it's true, 90%.


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## Oneacer (Jan 3, 2011)

And the occasional mouse chewing wires.


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## Oneacer (Jan 3, 2011)

Even many froze cylinders from sitting can be freed by taking out the plug, spraying in some good penetrating oil like Trizol, let it sit, then slowly turn the crank back and forth with a wrench ... make sure you go easy starting out.


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## carguy20 (Feb 8, 2021)

Oneacer said:


> Even many froze cylinders from sitting can be freed by taking out the plug, spraying in some good penetrating oil like Trizol, let it sit, then slowly turn the crank back and forth with a wrench ... make sure you go easy starting out.


I was able to do this with a 2 cycle i picked up that had been sitting for years. After breaking it loose, it started perfectly. I can't speak to using Trizol, I personally use Marvel Mystery oil, simply because I have several quarts of it that I picked up for dirt cheap. 

My new hobby / addiction is finding broken blowers and fixing them up (if possible) to give to friends / neighbors who otherwise would not buy one new because of cost.


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## chipg1956 (Mar 28, 2021)

Is this a flathead? If you continue to be frustrated you may want to give it a compression test. The 5hp Tecumseh, more then any flathead I have seen, has a tendency to lose valve lash. Which can also explain why it spits fuel out of the carb..


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## badbmwbrad (Jul 30, 2019)

Yes; it's a flat head Tecumseh. It sure feels like there's plenty of compression. I'm thinking that when I'm finished troubleshooting this engine, I will have removed the flywheel to inspect the ignition points. 

Once I've gone that far with a disassembly, it's just a few bolts away from removing the cylinder head. 

I'd really like to understand why the carburetor is spitting out so much fuel when I run the electric starter. Maybe a mouse has built a next inside the muffler; blocking the airflow


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## carguy20 (Feb 8, 2021)

I know most of the tecumseh's I have seen have a closed muffler, the square / cube kind of thing where a mouse would have to be houdini to get in there. The easiest way is to put your hand over it while you are turning with the pull cord it to see if it feels like it is pushing air out of the muffler on the exhaust stroke.

Just curious, have you tried to start it without letting the carb have fuel to it. I'm curious if it is flooding itself to where it will simply not ignite. It sounds like there is quite a bit of fuel coming out of the carb, the wrong way. Maybe with just a little starting fluid it might ignite and run momentarily.


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## chipg1956 (Mar 28, 2021)

By the way, where are you in Mass? If near Springfield I may have some machines I can sell you real cheap, scrap value. I have been repairing small engines for about 20 years. Right now I am having back problems and do not have the ambition to fix the machines that I accumulated over the last season. If you or anyone else near me is interested please email me at [email protected] or text me at 413-668-5823.


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## T. L. Kott (Jul 14, 2021)

Heating the spark plug up helps too...


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## Johner (Dec 30, 2020)

Not sure you have it fixed yet. Believe instructions will say "do not prime starting with battery" If you press primer if it has one the gas will come out of the carb. vent hole , should not choke if that is the case, engine is flooding. Also check the valve lash . it might have easy start , give a couple .002, if flooding occurs remove spark plug , blow off the plug, turn engine over to remove excess fuel. And try new spark plug. And yes could have a float problem . If you blew the carb out you may have blown the float valve across the room never to be found.


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## badbmwbrad (Jul 30, 2019)

I've been busy with school work and haven't had a chance to revisit this snowblower. It's easy enough for me to remove the flywheel and see if the ignition points have closed up. Otherwise, I can remove the cylinder head and valves and adjust the tappet clearance.


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## badbmwbrad (Jul 30, 2019)

I removed the blower housing and see no ignition points. The engine has no compression. I removed the valve cover and find there is no valve tappet clearance.

The engine is a Tecumseh small block horizontal 5 HP Snow King. The model numbers are rusted off the blower housing but it probably starts with HS50 or HSSK50. Valve clearance is supposed to be 0.004" - 0.010".


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## badbmwbrad (Jul 30, 2019)

This snowblower engine barely starts up, spits gas continuously out the carb throat during electric-start engine cranking, then stalls. It won't restart. The problem is caused by no valve tappet clearance or so I thought... 

Whatever compression it's able to develop gets pushed out the carburetor. Adjusting valves on a flathead engine requires cylinder head removal and valves removal to grind away some of the valve stem. Most people would throw away the machine before they would pay for the labor to do this because it's really not worth it. I've done valve clearance adjustment on a Tecumseh L-head engine and will do this just because I want to fix it for my own gratification.

I removed the cylinder head and turned over the engine crankshaft. Exhaust valve was snapping closed and valve timing and sequence was all wrong. WTF? The dipstick was absent from oil fill cap. Internal inspection revealed a broken camshaft. Metal dipstick got caught between crankshaft/camshaft's respective timing gears. The gear teeth knurled the dipstick's entire length. Amazing!


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## Johner (Dec 30, 2020)

Wow that is a first for me. What is your course of action?


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## jherbicide (Oct 14, 2021)

Oneacer said:


> A replacement carb is like 12-15 dollars .... That should put you back in buisiness.
> 
> Spark gap is 30 .... 20 is not good.
> 
> ...


Av Gas won't hurt a thing except maybe your health (lead). I ran it for years because I could get it relatively cheap and it basically erases any normal fuel related issues.


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## Johner (Dec 30, 2020)

jherbicide said:


> Av Gas won't hurt a thing except maybe your health (lead). I ran it for years because I could get it relatively cheap and it basically erases any normal fuel related issues.


I suppose the dip stick fell off?


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## jherbicide (Oct 14, 2021)

badbmwbrad said:


> This snowblower engine barely starts up, spits gas continuously out the carb throat during electric-start engine cranking, then stallw. It won't restart. The problem is caused by no valve tappet clearance or so I thought...
> 
> Whatever compression it's able to develop gets pushed out the carburetor. Adjusting valves on a flathead engine requires cylinder head removal and valves removal to grind away some of the valve stem. Most people would throw away the machine before they would pay for the labor to do this because it's really not worth it. I've done valve clearance adjustment on a Tecumseh L-head engine and will do this just because I want to fix it for my own gratification.
> 
> I removed the cylinder head and turned over the engine crankshaft. Exhaust valve was snapping closed and valve timing and sequence was all wrong. WTF? The dipstick was absent from oil fill cap. Internal inspection revealed a broken camshaft. Metal dipstick got caught between crankshaft/camshaft's respective timing gears. The gear teeth knurled the dipstick's entire length. Amazing!


wow is all I got. I wanted to 'like' your post but I certainly don;t like that it happened!


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## tadawson (Jan 3, 2018)

Since when did an L head have a dipstick that long? Gotta wonder if someone shoved something into it, it went bang, and they failed to 'fess up . . .


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## badbmwbrad (Jul 30, 2019)

This is a Tecumseh HS50 with a camshaft PTO and a crankshaft PTO. It has a dipstick tube that's at least 8" long. I think the stick separated from the oil fill cap and went into the cam timing gearset. The blower was free and now I know why 😁 The guy had posted it on Facebook Marketplace and said he was moving away, didn't need it anymore. It's a learning experience for me. Someone else will be getting a free Ariens Sno-Thro soon!

My understanding is that there is no good replacement engine for one of these dual PTO Tecumseh engines so this Sno-Thro is a parts machine.


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## carguy20 (Feb 8, 2021)

You should be able to find a dual shaft engine without too much trouble. It may take a little time, but if the machine itself is in good shape (rust, etc.) I would certainly not scrap it just yet. You might even be able to find an 8hp dual shaft that would really give that blower a little boost.


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