# Tecumseh 10hp snow king won't fire



## Mbisson (Dec 4, 2015)

I did professional carb cleaning, cleaned gas tank, new fuel, oil change, new spark plug, checked for spark, etc. All is good. Problem is engine won't fire. Gas etc is all working as it should. If I put gas or quick start in spark plug hole, it drips out of carb. When I reinstall spark plug and start it. It fires up first pull and burns remaining gas in chamber but doesn't draw from carb. I checked intake and no blockages. Should I assume that intake valve is out of adjustment or broken?


----------



## AVB (Nov 28, 2014)

I would still suspect carburetion problem. Adjusting the valve won't hurt but is pretty well okay since the engine will fire and run on induced fuel.

How did you clean the carburetor specifically? Spray cleaner, Dip cleaner, or Ultrasonic?

To check for valve sealing problems you would need to do a leak down test.


----------



## Mbisson (Dec 4, 2015)

Carb cleaning was done by removing all rubber, emulsion tube, then manually poking out all the holes in low jet, main jet, emulsion and freeze plug area. Replaced all gaskets. I also had soaked main carb body and bowl with degreaser, then sprays with carb cleaner and blown dry. Reassembled. I was getting this exact same issue before carb cleaning. What do you mean by leak test?


----------



## AVB (Nov 28, 2014)

It is a pressure test for checking valves, cylinder condition, and gaskets. Here is Wikipedia article explaining the tester and it use.
https://en.wikipedia.org/wiki/Leak-down_tester

For carburetor cleaning I don't know if the degreaser will dissolve the varnish and other fuel residues in the carburetor metering passages; I have never tried it. I have only used the carburetor dip cleaning solution for soaking and it will not always get everything out. Manually poking through the metered holes you risk enlarging these or impacting what your trying to remove.

Here I nearly completely switch over to ultrasonic cleaning as tends to clean a lot better and uses only soap and water which is does produce a near non-toxic waste product and can be safely dispose of. I only use the dip cleaner now in extreme cases.


----------



## Mbisson (Dec 4, 2015)

As for carb cleaning methods. I've done hundreds of carbs of this exact kind as I repair Tecumseh models often but I always farm out engine jobs. I've never had one like this scenario. It is usually obvious when something is blown up and I just don't take that job. This carb was very clean so I gave it the short easy cleaning method. My degreaser I use is basically 100% pure soap. It works well to remove grease and expose varnishing but doesn't remove varnishing. That's when I use my brass braided wires to clean out ports and carb cleaner/ comp air to clean out. There was no varnishing at all in bowl or on jets and Emul tube. That's why I think the intake valve is either broken or spring is broken or something with push rod is broken preventing a seal and thus preventing the needed vacuum to draw fuel. Am I seeing this right?


----------



## AVB (Nov 28, 2014)

If the valve weren't working right you wouldn't even be able to get it to run on induced fuel as intake has to open to draw in fresh air and fuel and the exhaust to expel the waste gases. If either one wasn't closing the engine would not run as the cylinder would not develop the needed compression for the fuel to ignite.

I can link you to the service manual but I need to know if your engine is a L-head or an OHV engine as these SK engine came in both versions.


----------



## Mbisson (Dec 4, 2015)

L head. Thanks. I took the head off yesterday. Intake valve clearance was .008 and the exhaust valve clearance was .000. However, neither the exhaust or intake valve we loose at top dead centre which I would expect of there was no clearance on the exhaust valve. So all the telltale signs I look for I can't find. So back to the carburetor. I guess the emulsion tube might be causing issues.


----------



## AVB (Nov 28, 2014)

Mbisson said:


> L head. Thanks. I took the head off yesterday. Intake valve clearance was .008 and the exhaust valve clearance was .000. However, neither the exhaust or intake valve we loose at top dead centre which I would expect of there was no clearance on the exhaust valve. So all the telltale signs I look for I can't find. So back to the carburetor. I guess the emulsion tube might be causing issues.


Now that can cause a start up problem with the exhaust valve at zero; seen that many times here on Briggs engines. The exhaust is normally at .012". That lower of clearance can cause starting problem as the decompressor would be overly active. To adjust adjust this clearance would require removing the valve and lightly squarely filing the stem end where it meets the lifter. Be carefully it can be over done easily. After each filing the valve needs to be re-installed with it spring and cycled a time or two make it is fully seated when checking the clearance. Some over filing can be removed by resurfacing the valve and seat area.

Here is a link to the 3-11hp L-head manual.
http://www.mymowerparts.com/pdf/Tec...P-4-CYCLE-L-HEAD-FLAT-HEAD-ENGINES-692509.pdf


----------



## Mbisson (Dec 4, 2015)

Ok. Thanks I'll check it out.


----------



## Mbisson (Dec 4, 2015)

So how should i do this? How to remove exhaust valve? Can I simply compress spring and just shave between push rod and valve without removing valve? Is there a specific tool I need? Thanks a bunch!


----------



## AVB (Nov 28, 2014)

You need to remove the valve from the engine. Trying to file it while in the engine will leave filings that can fall down into the engine which can be pickup and damage the engine otherwise. Getting the valves out depends which retainers they have. Some are key holed and there is some split retainers like automobile engines used. Here is the valve spring compressor that I use on most of the L-heads that I work on too compress the springs so the keepers can be removed.


----------



## Mbisson (Dec 4, 2015)

Ok so removing is the important part. I know that the holder is not what I'm used to working with. Usually I work with the ones that have a radius cut. This one is likely key. So lift rotate and slide out. So I need to compress spring first. Ya?


----------



## AVB (Nov 28, 2014)

Yes and if the key hole version then it would compressed and slide out place to release it.


----------



## Mbisson (Dec 4, 2015)

Ok. I'll give it a shot but I don't have that tool so I'll see if I can make due with random contraption.


----------



## Mbisson (Dec 4, 2015)

Alright so I adjusted exhaust valve clearance and reassembled. Now she runs. But it's clear there are more issues. She knocks and seems to be burning oil. Although I ran it for 30 seconds ish as I didn't want to blow up the engine. Connecting rod loose? Worn rings? Cylinder looked good and piston seemed fine when I hade it open. What do you think? I can see that the high rpm setting is revving high so probably over rev.


----------



## AVB (Nov 28, 2014)

You did clean off the carbon build-up on the head and piston while you had it a part?

Knocking can be cause by several things including the above carbon build-up. The only if it is over revving is a tach. Most likely your engine has a 3600 rpm max rating. This could be that someone has moved the governor linkage static adjustment and they did it can cause over revving easily as governor would no longer work properly.

Yes a loose rod cap can cause problems as the engine been ran without oil causing rod seizure. 

I afraid there is only one find if something is loose or damage inside the engine and that is go inside and look around.


----------



## Mbisson (Dec 4, 2015)

Yes I cleaned carbon deposits. Initial oil was very oil and viscosity was non existent. Settings were tampered with at some point. Linkage to governor was bent and set screw for high RPM set deeper than stock. I'm afraid I have to open up sump and investigate further. Either way. Nothing simple or cheap remains now. Lol. I really apprecIate your guidance by the way. Gave me the extra it of confidence I needed. It had been a while since I got this deep in an engine and had never done Tecumseh this deep. I might post an update or further questions. We'll see but thanks again.


----------

