# Diagnosing a generator problem



## MichaelK! (Oct 22, 2010)

I use my 6kw AC Delco generator to supply power to our 240V well pump. The last time the generator was used in November, it performed nominally, and was shut off normally, and left sitting over the winter in the unheated well shed.

Come April, and the generator is locked up. After the first pull of the starter rope, the engine seizes up and stops turning. I've removed the starter rope assembly so I can get at the main engine shaft. Here's what I've observed.

I removed the spark plug so I could see the piston head. The head looks OK, with little carbon buildup. I ran a wire probe inside the cylinder to feel for broken chips, but I can not find any. The spark plug looks intact with nothing broken off it.

Grabbing the main engine shaft, I can rotate the engine freely either clockwise or counterclockwise until the piston reached TDC, where it locks up. It turns just slightly less than 360 degrees either way, but stops at TDC.

My guess would be that a valve might have rusted open and is preventing the piston from reaching the top of it's travel. My next plan is to remove the valve cover and try to observe whether or not the valves are moving as the engine is turned by hand. Would a tap with a hammer on the top of a valve stem break it free? That would be my next course of action unless anyone else has suggestions otherwise.


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## wy_white_wolf (Oct 14, 2004)

Spray wd-40 in the spark plug hole then blow compressed air in. There should be splatter out the exhaust or carb depending on which valve is stuck open.

Be carefull tapping on the valve stem. I've had spring keepers pop out doing that. But I've also had it unstick a valve.

WWW


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## agmantoo (May 23, 2003)

I agree that the valve is probably stuck. I would remove the muffler and spray PB Blaster through the exhaust opening and let it soak for a few hours. I a NOT a fan of WD 40.


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## BlueFlames (May 28, 2006)

Just soaking it for a day or two in PB Blaster, Diesel or WD40 should loosen it up enough that the spring may pull it back. Or GENTLY rotating it so the piston touches it may jar it enough that the spring does its job.

If you can do so safely, heating the head up with a heat lamp may cause the valve guide to swell enough to get the valve stem broke loose.

Good luck!


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## MichaelK! (Oct 22, 2010)

Success! Spraying WD-40 worked! I started with the easiest procedure, which was spraying some WD-40 into the cylinder. After spinning the piston back and forth a few times, the ring must have slid over the rusted portion and was turning again.

I then get the plug back in, attached the starter rope again and started pulling. It didn't try to start till about the 8th pull, then it caught on, and starting chugging out blue smoke. After about 15 seconds, the spray oil got burnt out, and the RPM stabilized and the engine was running normally.

I flipped the AC on and hooked up a power tool to put a load on the generator. I left the load on for about 5 minutes, then I shut it down and started draining the used motor oil.

Thanks for the suggestions!


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## Fire-Man (Apr 30, 2005)

Good, each time you shut it off with no plans of using it again for a while, take a few seconds and pull the cord till you feel the compression stroke-----leave it there-----that way your valves are closed and will help keep out moisture.


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## MichaelK! (Oct 22, 2010)

Fire-Man said:


> Good, each time you shut it off with no plans of using it again for a while, take a few seconds and pull the cord till you feel the compression stroke-----leave it there-----that way your valves are closed and will help keep out moisture.


Never heard of that one before. Sounds like a great idea. Thank you! Will do it next time.


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## Fire-Man (Apr 30, 2005)

MichaelK! said:


> Never heard of that one before. Sounds like a great idea. Thank you! Will do it next time.


I do all my single cylinder motors that way. Something I got in the habbit of doing with high dollar racing engines for go karts.


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