Small Engines (Lawn Mowers, etc.): Snowblower wont restart after its hot, trouble shooting guide, valve clearances

Question
I have a 1995 MTD single stage snow thrower with a Tecumseh engine HSK600  1627S. It starts fine from a cold start after priming and a few pulls. It will run for a while ~ 10 15 minutes, but if you shut it off or it stalls it will not restart ( for at least 10 minutes ). It seems like it floods itself and does not want to catch. I have replaced the plug and put in fresh gas/oil mix. It has operated this way for the last two years - I just try to clear the whole drive before shutting it off or stalling it. Last year I rebuilt carb w/ a new float, needle valve and seal. what would cause it to not start after it is hot?

Thanks!!

Answer
Hello Greg:

You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.outdoordistributors.com/ and Select the T. Then Select Tecumseh. Then Select Don't have Part Numbers. Then Enter the Model Numbers HSK600-1627S. Then Select your Model and Download the File for Online Viewing. Since this is a Tecumseh Engine, I have a PDF Site Addy that May Assist you Also. http://www.tecumsehpower.com/CustomerService/BSI.pdf  .  This Site Addy; http://www.outdoordistributors.com/Tecumseh/tmain.html has a Link to a PDF Trouble-Shooting Guide. Simple Select the Free PDF Download for the "Tecumseh Trouble-Shooting Guide". From your Description it Sounds like; 1- the ign Coil is Heating up and Requires Replacing. 2- the Valve Clearances Require Setting. Once the Engine has Heated up the Valve Clearance is too Close and Reduces the Compression and the Unit will be Hard to Start or Simply will Not Start. Lets Do some Diagnostics. 1- The Following is an Instruction File I Made for Checking and Repairing this Problem. Run the Engine Until it Quits, then Remove the Spark Plug. Wrap a Wire Around the Threads and Attach the Other End of the Wire to the Engine Block Turn the Engine and See if the Plug Fires. If No, then Disconnect the Shut Off Wire  at the Control Bracket First, Check for Fire at the Plug. If Still No Fire at the Plug; Then Disconnect the Shut Off Wire at the Coil (usually requires removal of the blower housing) and Check for Fire at the Plug. If No Fire at the Plug , then the Coil/Ign Module is Bad. The Coil/Ign Module to Flywheel Gap is .020in. On Some Model JD Engines, there is a Igniter that Goes Bad and Not the Coil. The Igniter is the Same as an Ignition Module. If the Plug Fires at Anytime During these 2 Checks, then a Safety Switch or Wire May be the Problem. Yes the Engine will Turn Even with a Bad Safety Switch. The Blade Safety is Usually the Cause of this. The Starter Turns and The Engine Doesn't Fire is an Indication of a Bad Coil/Ign Module or a Faulty Blade Safety Switch. The Clutch Safety Prevents the Starter from Engaging so the Mower Does Not Move when the Starter Turns the Engine. The Seat Safety is Designed to Stop the Engine if the Blades are Engaged or the Clutch Safety is Not Engaged when you Leave the Seat. 2-  The Following is a Basic Instruction File for Setting the Valve Clearances on Non OHV Engines. Any Input is Appreciated. On this Model Engine I Usually Suggest Reseating the Valves if the Valve Clearance Requires Adjusting. The Following is a General Instruction File for Setting the Valve Clearance on Non OHV Engines. **Remove the Carburetor and the Crankcase Breather/Vent and the Valve (Stem) Cover so you have Access to the Valve Stems, Springs and Keepers. Set 1 Cylinder to TDC on the Compression Stroke. Using a Blade Style Feeler Gauge, Check the Clearances. The Intake should be .005in - .007in and Exhaust .008in - .010in. If the Feeler Gauge will Not Slide Between the Valve Tip and the Tappet, then you Must Reset the Clearances. **You Will Require a Small Engine Valve Spring Compressor to Remove the Springs and Keepers from the Valve Stems.** Some Engines Use a Valve Keeper that is like Automotive Keepers (2 Cone Shaped Keepers that Set in the Valve Retainer/Rotocoil Assembly)and the Other Style is a Slotted Retainer that is Moved (once the Valve Spring is Compressed) to the Larger Opening in the Retainer and the Retainer Slips Over the Valve Stem Tip for the Valve to be Removed. Remove the Heads. Set 1 Cylinder so the Piston is at TDC on the Compression Stroke And Check the Clearances Between the Valve Stem Tip and the Tappet. The Clearances are as Follows: Intake Valve Clearance is .005in - .007in and the Exhaust is .008in - .010in. You have to Lightly Grind the Valve Stem Tip and Place the Valve Back Into the Engine (you can Hold the Valve Seated by Hand) and Check the Clearance Until you Reach the Required Clearances. **++** For this Engine Model I Suggest you Reseat the Valves while you are Setting the Correct Valve Clearance. For this you will Need a Small Valve Seat Suction Tool. This can Usually be Purchased for $10.00us and has a Suction Cup that Hold the Valve Head so you can Turn the Valve Back and Forth and Dress up the Valve Seat. Valve Grinding Compound is Approximately $5.00us a Tube and a Tube Last the Shop About a Year. It Doesn't Take a Lot to Reseat 1 Engine.**++** Once the Valve Clearances are Reached and the Valve Seat is Nice and Dull; Re-Install the Valves on that Cylinder and Turn the Other Cylinder to TDC on the Compression Stroke and Set that Cylinders Valve Clearances.  Once that Cylinder is Set, Assemble the Engine.** If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. Have a Happy Holiday Season and May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Comments and Ratings are Greatly Appreciated. Thanks.

Respectfully

John