Small Engines (Lawn Mowers, etc.): TORO Engine Surge

Question
TORO Super Recycler  Mod  20474  Ser  6905779  
Twice in the last 6 wks  when the mower started, a rather large puff of blue smoke came out.  No smoke after it was running.  Now when mower is first started, it runs OK but after a few minutes a surge or pulsating starts. It does not emit the smoke every time it starts,only has done it twice. This is an OVH engine.  Any thoughts?  Valve seals?  Thank you.  Chuck

Answer
Great engine on that mower...but it is getting old so a puff of blue/white smoke can be expected as the rings, piston and valve guides are wore.

Are you using SAE-30 oil?  How often do you change the oil?  Have you ever checked the valve clearance?

You can download the engine service manual from Toro's website...it is the 49 page manual.

The surging is most likely caused by a fuel issue, usually the carburetor or a leaking intake part/gasket.  Since it takes a few minutes for the surging to begin the something may be warming up and expanding which then starts to leak.

When was the last time the carburetor and fuel system was cleaned and serviced?

Again, those were great engines and mowers.  Reliable and dependable.  It is difficult to find mowers today that were as good as the mower you have.

Eric