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First post; thanks for providing the public forum.
I bought a really nice Husqvarna from an estate sale recently. Several years old but well taken care of. Other than this ...

Guy stated the owner (uncle/grandfather, I'm not sure) started it in his presence and almost immediately it made a noise he described as like a shotgun blast and blew oil across the shop. We could still see the stain about 12 or so feet across the floor. So he sold it to me for a song, assuming the engine was toast.

So I start to take it apart today, and the first thing I notice is oil dripping from the exhaust port (in front of the mower on this model).

Go to drain the case - it's full of what looked to be an oil/gas mixture - mostly gas - I'm guessing maybe half a gallon.

Take the engine off the chassis expecting to find a hole somewhere from catastrophic failure.

Nothing. Case looks fine. Pan looks fine. Valves, cylinders, and heads look fine, though with a good bit of charring in the usual places. Other than that, everything looks fine. Rocker arms, pistons, shaft - everything seems to be in working order, and no obvious signs of catastrophic failure. Governor (my original suspect) fine.

So now I'm wondering - could this guy just have had a few too many and put gas in the crankcase instead of the gas tank?
Is it possible that when he started it up, it just blew all that oil past the valves and out the exhaust port?

I have a couple of parts engines and one full 28hp that hasn't been used in a long time; I was planning to try the old 28hp or use the parts to repair this one. But at this point, I'm considering just cleaning it up, replacing the head and valve cover gaskets, and putting it back on.

I can do these repairs with no problem - but I'm far from a small engine expert.

Anyone want to share your thoughts?

The carb float valve has failed so it will need to be cleaned & tested before the moower goes back into service
This allows fuel to drain / syphon from the tank into the engine because the float bowl overflow is inside the manifold
The petrol then dribbles past the rings & fills the sump
When this happens there aare some consequences that need to be checked
1) bent con rods ( Both pistons should come up to the very top of the bores and both should be the same
2) blown head gaskets ( more common on singles than twins )
3) bent breather valve reed ( check by blowing & sucking through the breather tube - should suck but not blow -yummy )
4) Broken starter pinion tooth ( visual check )
5) cracked / broken timing key in flywheel ( visual check )

You will probably find the muffler full of oil and that will make white smoke for up to a couple of hours after you get it back together
I always fit a tap to the fuel line before the pump
If nothing else it makes changing the filter &/or pump plus cleaning the carb a lot easier & cleaner

bertsmobile1 said:

The carb float valve has failed so it will need to be cleaned & tested before the moower goes back into service
This allows fuel to drain / syphon from the tank into the engine because the float bowl overflow is inside the manifold
The petrol then dribbles past the rings & fills the sump
When this happens there aare some consequences that need to be checked
1) bent con rods ( Both pistons should come up to the very top of the bores and both should be the same
2) blown head gaskets ( more common on singles than twins )
3) bent breather valve reed ( check by blowing & sucking through the breather tube - should suck but not blow -yummy )
4) Broken starter pinion tooth ( visual check )
5) cracked / broken timing key in flywheel ( visual check )

You will probably find the muffler full of oil and that will make white smoke for up to a couple of hours after you get it back together
I always fit a tap to the fuel line before the pump
If nothing else it makes changing the filter &/or pump plus cleaning the carb a lot easier & cleaner

Click to expand...

Never considered that option, but it makes sense.

Rods, gaskets, and starter teeth all looked fine. Flywheel turns with the shaft, so that should be okay I would think - but I'll check to be sure. Flywheel is heavily rusted and coils are in bad shape, so certainly new coils will be a priority and cleaning the rust off that flywheel.

Very infomative response; thanks for all that information.

LEave the flywheel alone and the same with the coils
If they needed rust protection then that would be done at the factory
Rust is not a problem for magnetic fields unless the build up is so thick it bridges the gap.
What is important is the coils are grounded so if you want to exercise the wire brush limit it to the region wher they bolt down on both sides plus the underside of the bolts .

Can this also be caused by a diaphragm failure in the fuel pump? Engine vacuum sucking fuel into the crankcase from the back side of the pump? I know on newer OHV engines the vacuum is pulled from the valve cover but I seem to remember my dad having a fuel dilution problem with an older flathead engine where the vacuum source was from the crankcase.

I now install a fuel shutoff on any small engine I own. Cheap insurance.

Elkins45 said:

Can this also be caused by a diaphragm failure in the fuel pump? Engine vacuum sucking fuel into the crankcase from the back side of the pump? I know on newer OHV engines the vacuum is pulled from the valve cover but I seem to remember my dad having a fuel dilution problem with an older flathead engine where the vacuum source was from the crankcase.

I now install a fuel shutoff on any small engine I own. Cheap insurance.

Click to expand...

It could be a failure in the fuel pump but that issue is a lot more rare than people will realize. I have sold 5 vacuum fuel pumps over the last 25 years due to the pump actually failing. And of those 5 there was 1 that actually was leaking fuel. Have probably replaced more of the old mechanical pumps on Kohler engines than that due to fuel leakage into the crankcase.

Pumps sold over the counter due to the customer thinking that had a bad fuel pump 50.