Cub Cadet SC300hw Lawnmower

[bgsengine]

I'd be checking compression and/or valve action - hit something, might have sheared camshaft gear key, throwing valves out of time. maybe pop valve cover off and see if valves move freely and/or seat properly

[dart451]

I'd be checking compression and/or valve action - hit something, might have sheared camshaft gear key, throwing valves out of time. maybe pop valve cover off and see if valves move freely and/or seat properly

But would it start so easily with starter fluid and keep running with little squirts of starter fluid? It actually runs good if I keep feeding it fuel...

[bgsengine]

I'd still check compression - You'd be surprised what a little bit of valve issue can do - once they GET running, they can seem to run pretty good, but they still got valve issue (Think of a hot restart problem for example) shock from the strike could also have caused something to shift or even crack (such as a intake manifold flange?) giving you an air leak... especially considering those engines don't get the best quality control inspections....

[dart451]

I did a compression test and I'm getting about 45 psi...but I'm not sure if I'm doing it right! I always thought you had to have your throttle opened fully for compression tests but not sure. I checked my new DR Trimmer that also only has a few hours on the engine and runs beautifully...it only had 30 psi! So what the heck!?

[creia]

I did a compression test and I'm getting about 45 psi...but I'm not sure if I'm doing it right! I always thought you had to have your throttle opened fully for compression tests but not sure. I checked my new DR Trimmer that also only has a few hours on the engine and runs beautifully...it only had 30 psi! So what the heck!?

Your compression tester gauge is defective. Yes, you do always open the throttle all the way to test.
Michael

[dart451]

Funny, I did check the compression tester with my air compressor, it's showing the correct air pressure of the compressor...but it is old, maybe I'll buy a new one...
]

[bgsengine]

Funny, I did check the compression tester with my air compressor, it's showing the correct air pressure of the compressor...but it is old, maybe I'll buy a new one...
]

You ARE cranking engine over until the compression tester gauge needle stops moving, right? just 1 or 2 pulls is seldom enough to get accurate readings.

[KE4AVB]

It depends a lot on the placement of the schrader valve if not right at the cylinder small cc engines will not have enough volume to open it as they must pressurize the hose first before the valve can open on every cycle. A compression tester with this schrader valve right at the cylinder can open the valve then pressurize the hose and gauge then the valve close before any of the built up pressure is lost.

My Actron compression tester this schrader valve right at the end of the rubber hose next to the cylinder and I get very accurate readings within a few pulls.

[dart451]

Excellent! Yes, I was pulling the thing over four or five times...and what I did was borrow my son's compression tester. I got almost 80 psi on the engine now, on my new DR, I think it was 75psi. So, it appears for some reason, the carb is not getting fuel. Now, I also tried completely closing off the air to the throat of the carb while my wife pulled the engine over and it did try to start also getting my palm wet with fuel. So, I believe with good compression and fuel flow to the carburetor, I'm going to try a new carburetor...

P.S. I'm going to order a Actron compression tester...the one I have is about 30 years old...

[KE4AVB]

And for that see the AZUNO Digital Compression Tester and it think will work on small think again. I brought one and it failed miserably. My Actron was reading 120 psi when the Azuno was only reading 20 psi.