Toro Zero Turn smoking

I have seen one that smoked on start up after setting a while. It turned out to be fuel smoke because it was carb leaking slowly into the intake. It was a light blueish smoke.
 
Symptoms point to valve stem seal leakage, or worn valve guides. Mostly intake valve stem seals will allow oil into the intake when vacuum is high, or given time for oil to seep down the guide around the stem.
If you did not replace the valve stem seals, it would be a decent bet that doing so might cut out the blue smoke on startup. You can do it without removing the cylinder head. Feed a length of rope into the spark plug hole, and then rotate the crankshaft to have the piston hold the valves closed. Pop off the rocker arm and valve spring, pry off the old seal and put on the new one. I'd apply a bit of oil to ease the seal over the valve stem tip. Replace the spring & keepers, and the rocker arm. Remove the rope, replace the plug, and see what happens. You will have to insure the crankshaft does not rotate once you have placed the rope and blocked the valves from falling into the cylinder. Clamp the flywheel or the pulley on the PTO.
tom
 
Tomw0 is I feel on the correct path. if you swap out the valve guide seals and it stops smoking and then starts smoking again in a month or two then you have worn guides as well if thats the case its probably cheaper to just replace the engine.
 
kenn_chan said:
Tomw0 is I feel on the correct path. if you swap out the valve guide seals and it stops smoking and then starts smoking again in a month or two then you have worn guides as well if thats the case its probably cheaper to just replace the engine.
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Unfortunately that’s not an option. The customer priced an engine at 1250 after freight. And wants this one rebuilt etc. this is a huge headache
 

cylinder head complete ... $213.xx .... lots less than $1250. If the customer wants it to work properly and will not stand for a slight puff of smoke on startup, then it will cost at least this much to replace the head. Doing the valve stem seal(s) may reduce the puffing. An alternative is to have the valve guides reamed or drilled and new guides pressed into the cylinder head. Then ream the guides to the proper size to fit the valve stem diameter. All of that labor will likely be more than a new cylinder head.
A second alternative, or third.. fourth... would be to find a used head that was in better shape.
I am not on the clock, so I would have taken the head apart when I had it that far, and checked the condition of the valve seats, the fit of the stem to the guide, and certainly replaced the seal. If you want no smoke, you will have to do the 'rope' thing, or remove the head and refurbish is or replace it.
I see no alternatives...
tom
 
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