Tecumseh VLV126 too hot

[Cosmopolit]

Hi to all the tech-savvy here.

I am writing from Berlin, Germany, as no repair shop here wants to deal with Tecumseh.

I have a riding mower, Wolf Garden Scooter SV4, some 20 years old, with a Tecumseh VLV 126 engine. It runs, but not good:

1. It gets too hot. When cold, it starts quite easily, but after 2-3 minutes it gets so hot, I can hardly keep my ankle closer than 10 cm to the muffler. The metal frame, too, that holds the engine, is so hot that I can barely touch it. I mow for a few minutes, than let it cool for half an hour, then again use for a few minutes… This is not how it should be.

2. It lacks power. When cold, it often stops as soon as I engage the blade. I am not very savvy., but it seems to me that the sound of the engine, when idle, is not very smooth.

3. Also interesting, coherent or not: when I pull the cord for starting (electric starter does not always work), and the other hand touches the frame, I sometimes get an electric shock.

I know there may be many causes… What I did until now: changed the oil, the air filter, the entire carburetor, the spark plug. Gasoline is fresh.

What I suspect, but did not yet check: the flywheel, flywheel key, alternator and the ignition. Any idea?

Thank you, Cosmopolit

 

[Slick3914]

First thing I would check is the ignition timing and clean the carburetor. Also check the fuel cap vent and change the filter.

 

[Eddie]

Remove the engine cover and clean out any debre causing low air flow.

 

[tundraotto]

valve lash adjustment is due....

 

[spasm3]

Pull the spark plug when cold and examine. See if its running lean.

 

[Cosmopolit]

First thing I would check is the ignition timing and clean the carburetor. Also check the fuel cap vent and change the filter.

Thank you for the fast reply. Carburetor is new, but yes, I can clean it again. Fuel cap is open, checked already. There is no gas filter, and the air filter is also new. Now, ignition timing, yes, this is one of my suspects- but can this symptom, getting too hot, come from bad timing?

 

[Cosmopolit]

Remove the engine cover and clean out any debre causing low air flow.

Thank you, Eddie. Yes, I did this already, there is absolutely no obstacle for the air.

 

[Kamele0N]

Yes....why not! If it ignites a mixture just a tad too early....it will run hotter...

Same applies if its valves are not set properly... Especially exhaust valve...

 

[Cosmopolit]

Pull the spark plug when cold and examine. See if its running lean.

Thanyk you, spasm. Spark plug is new, and the old one did not show any clear signs of either lean or fat burning.

 

[Kamele0N]

Will have a look when I come home for a Tecumseh service manual(s)...

 

[Cosmopolit]

valve lash adjustment is due....

Thank you, tundraotto. Well, yes, valve adjustment is also on of my suspects, but this is probably too much for my ability. I am afraid I cannot full open the engine and then reassemble it again, some of the screws are too bad rusted, and spare parts are almost impossible to obtain.

 

[Kamele0N]

Easy peasy
All you need is "ventielfederspahnzange"


Most probably your engine has recesed valves....valve seats....thats why it runs hotter...

 

[Lubener]

1. pull the cover off and clean all accumulated debris from the fins on the block and flywheel and everything under the cover.
2.When the cover is off, check and make sure the flywheel key is centered and not partially sheared which will throw off ignition timing.
3. As for the shock, check the condition of the coil and plug wire which is integral to the coil. Any damage there can cause your running quality.

I am not sure if your engine is OHV and I believe it is a flat head. Valve clearance issues will start to show up with hard warm starts. Unfornately, the only way to fix is to take some material off the valve stems.

 

[Slick3914]

Thank you for the fast reply. Carburetor is new, but yes, I can clean it again. Fuel cap is open, checked already. There is no gas filter, and the air filter is also new. Now, ignition timing, yes, this is one of my suspects- but can this symptom, getting too hot, come from bad timing?

It sure can, if it is retarded a few degrees the muffler will get very hot or glow cherry red.

 

[Cosmopolit]

OK, thank you. The diagnosis seems to be narrowed down to ignition times or valves. Both are quite difficult to check, as I have do open the engine for that. And yes, I will need this Ventilfederspannzange, long German Word for such a short tool ;-)

 

[super20dan]

valve lash adjustment is due....

these have non adjustable valves

 

[Kamele0N]

these have non adjustable valves

)

 

[Cosmopolit]

these have non adjustable valves

Yes, and this is exactly my concern: I saw this video, in which they grind (shorten) the stems. But what if the stems are already too short? Or does this never happen, they are , if faulty, always too long? Questions over questions... But yes, as I wrote, I will have to go deeper into it, and open the head.

 

[Kamele0N]

Valve stems are of proper lenght from a factory...

What happens here with those L-head engines is that valve seats (especially exhaust valve seat) wear out just a little bit...and because of that it looks like your valve is too long then...

 

[Lubener]

Valve stems are of proper lenght from a factory...

What happens here with those L-head engines is that valve seats (especially exhaust valve seat) wear out just a little bit...and because of that it looks like your valve is too long then...

Valve stems are of proper lenght from a factory...

What happens here with those L-head engines is that valve seats (especially exhaust valve seat) wear out just a little bit...and because of that it looks like your valve is too long then...

As the seat wears, the valve lash gets tighter not looser. So you will be taking a very small amount off the stem to meet specs.