Re: Kohler Courage Pro (SV735-0016) engine problems
I've torn down a more than a few seized Kohler Courage engines in the last couple years, and here's what I usually find: The top (flywheel side) crankshaft bearing is usually the first to go when something goes wrong. The oil pumps can fail on these engines, but it isn't as common as you may think. Even a good oil pump may turn a bit stiff by hand. The damaged flywheel magnets are, as you suspect, a result of the bearing failure, not a cause. When the upper crank bearing started to go out, the flwheel tilted to one side and the stator and magnets collided, causing the damage you see. Same may be true with the pistons...collateral damage. What makes me suspicious is the fact that both rods were fine. Most lack-of-lube failures cause damage to one or both connecting rods. Although, since the top main crank bearing is so far from the oil pump, it could also have locked-up before the Big Ends got hot enough to start transferring metal if the oil pump did indeed fail.
In my opinion, while an oil pump failure may have sure enough brought the engine down, there is another very deadly possibility, which few people realize is even there....
Your electric PTO clutch may have destroyed your engine.
Sound crazy? Let me explain. The PTO clutch is, of course, just a big electromagnet. It requires a constant 12V power supply and a good ground to operate, and it draws several amps of power during normal operation. Warner Electric had a problem with some of their clutches developing minor internal shorts a few years ago...right around the time your tractor was built. What would happen is the short would create a ground fault in the clutch. It wasn't bad enough to blow the fuse, but it would cause some of the power normally used to operate the clutch to fail to return to ground through the usual ground wire. Instead, the clutch would attempt to ground itself through another path of lesser resistance: The engine's crankshaft.
Stray electrical current travelling through the crankshaft would find its way to ground from the crank to the block by arcing across the engine's upper main bearing. It didn't take long for this constant arc to cook all the oil out of the bearing surfaces faster than the pump could replinish it, essentially welding the crankshaft and block together at the upper bearing. I've had a couple of these engines weld themselves together so tightly that not even repeated blows with a 5lb sledgehammer would dislodge the crankshaft.
Strange enough for ya? I know it sounds far-fetched, but I've personally seen 5 or 6 Courage engines die this way. Take your clutch off and bring it to the bench. Get a spare 12V battery and hook the clutch to it using jumper wires, so that the clutch snaps and stays 'ON' when you attach the cables. Now, grab an electical multimeter and put one lead to ground against the clutch's shell. Take the other lead, and touch it to the inner bearing surface in the top of the clutch. If your meter picks up ANY voltage, you have found your engine's killer. The clutch should be electrically neutral at the top (and bottom, for that matter) bearings.
Hope that helps! Good luck getting it going again.
Certified Kohler Master Service Technician
Shop Manager and Head Technician
Monroe's Small Engine Sales and Service
Rockingham, North Carolina
1971 Snapper Comet RER
1987 ?? Gravely 16G with hydraulic lift, front hitch, and front PTO
1987 Swisher Ride King, 8hp Briggs
1988 Echo PB 210 E
2002 Snapper Commercial 21"-Kawasaki FC150V powered
2006 Stihl FS 130 R
2006 Stihl MS 250
I'm not crazy...just obsessed.
Last edited by Poke; 06-11-2013 at 12:51 AM.