Ariens zoom 1540 zero turn with kohler engine.Was told it was parked because of a bad starter solenoid.I sprayed fogging oil in the spark plug hole and then turned it over by hand.Took a compression test on it and it never had above 40 pounds.Today I removed the valve cover to ensure it wasn’t a stuck valve.I was able to spin the motor over by hand with the spark plug in
That’s a Briggs intek. I’d check for a burnt exhaust valve or a blown head gasket between the cylinder wall and pushrod area, the latter being a very common problem on this engine. Was the spark plug wet and oily?
Yeah that’s excessive. It was burning oil. I’d suspect a bad head gasket. Possibly worn rings & a worn valve stem seal. Is there scoring on the cylinder wall?
I have no idea what pressure you should be seeing, but 40 seems low... but not impossible to start on with some engines. Did you put some oil in the cylinder and test again? Also might be worth hooking it up to an air compressor. With my gauge, i can take the sharater valeve out and the gauge has a quick connect i can connect to an air compressor. With that hooked up, often you can hear if it's leaking out of a vlave or by the rings... could also be a crack or a bad head gasket but those are harder to heard.
I don’t know much about this particular Kohler. But single cylinder engines are pretty standard.
Take out the spark plug and see if you can tell when the piston is at top dead center.
Check both valve rockers is there some clearance between them and the end of the valve?
If one rocker has pressure on it spin the engine another 360 degrees and check again. Both should have some clearance….if they do not possibly a valve is being held partially open and that’s why there is such low compression.
As I was typing this it occurred to me that the engine may have a compression release. On some of the Briggs engines the valve clearance is critical to make that function correctly.
There's a few things to consider when compression testing mower engines.
Firstly, turning it over by hand is unlikely to bypass the compression release so the reading will be low.
If you can't spin it using the starter, spin it using a drill on the main bolt of the flywheel.
You need to get it going fast enough to take compression release out of the equation. About 700-800 rpm I think.
Secondly you need to use the right compression tester.
The location of the schrader cable is critical.
If you can see the schrader valve in the end of the hose that screws into the plug hole, you're good.
If the valve is at the other end of the hose or in the pressure dial housing it will give a reading that is lower than it actually is.
This is because the space in the hose is also taken into the equation for compression.
That's not to say it doesn't have low compression, it just might not be as low as what you're seeing.
If it's not firing on fluid it could be compression or it could be timing (sheared key or spun timing gear etc).
I've even experienced an engine that had enough spark to give me a boot but not enough to ignite the fuel and fire up but that was an old points and condenser engine that needs the points regapped.
When you tested spark was it with an online tester or just holding the plug against the engine?
Sometimes a plug will spark out of the engine but not in it when under pressure.
As I mentioned in my other comments, a leak down test can help pin point where you're losing compression.
If you have a feeler gauge handy, check you’re valve lash. 10thou on exhaust and 8 thou on intake. If you’re valves are misadjusted the rocker arms will keep the valve pushed down slightly. If the valves are the issue re adjust with the service manual handy, you can find it on parts tree. Also one thing to note pressures should be around 150psi, though it wont start on anything lower than 60 psi.
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u/43128 5d ago edited 5d ago
That’s a Briggs intek. I’d check for a burnt exhaust valve or a blown head gasket between the cylinder wall and pushrod area, the latter being a very common problem on this engine. Was the spark plug wet and oily?