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Discussion Starter · #1 ·
Hey, new guy here!! Great forum you guys have here, this interwebz thing is awesome isnt it? I have a Craftsman 917.388531 and I think I may have screwed it up. I ran it for about 10 min this Sat, it startred fine and ran fine just as it has for the past 7 years or so but when I went to re-start it it wouldnt start. I noticed that it wasnt even acting like it wanted to start so I knew something was wrong.

I checked the oil and I noticed that it was REALLY low. I probably added more than 1/2 quart before it registered full. I assumed the worst and started looking for ways to confirm if the engine was blown. I bought a spark plug and borrowed someones leak down tester. When I screwed in the tester I didnt notice that the stem was at least twice as long as the spark plug. When I tried to pull the starter it rotated a little then stopped; like it got stuck or someting. I eventually figured out that the leak down tester was screwed in too far. I never got it to read any compression BTW.

I abandoned all of that, put the mower back together and tried to start it with the new spark plug and when I pulled it, it sounded like the muffler had come off. It didnt even act like it was going to start (again) but as the motor was turning over it had that loud open muffler sound.

I cant imagine what I could have done to cause this because the only screws I took off were the ones for the top cover and gas tank.

I read the other post from the guy that had a very similar problem with this exact mower and now that its after the fact I realize that a dirty/clogged carb is a much more likely culprit of my original problem but I digress.

http://www.mylawnmowerforum.com/for...r-craftsman-4-5-hp-will-not-stay-running.html

My basic question is if anyone has actually disassembled one of these engines and is familiar enough with the layout to tell me if there is a way I could have caused that noise to appear by screwing in the leak down tester too far? Sure, I could have cracked the piston or something but I didnt pull hard, just about a 1/4 pull then it stopped. I did have to use a wrench to remove the tester when I originally just screwed it in finger tight. Any help would be greatly appreciated!! Did I mention that this is a great forum :)

Mike
 

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Mike--I don't think that you would have broken anything if you only pulled the cord a short distance and the engine stopped turning over when it came into contact with the tester. My thought at this time is a stuck valve, possibly. Take the spark plug out, put your finger over the plug hold (with the plug wire out of the way) and have someone pull the starter rope. It should actually push your finger off the plug hole. If not you may want to consider pulling the head off the engine and see what is going on inside there. That should be an easy job, a half dozen bolts and a couple more holding the shroud on. You might need to get a new head gasket (probably should, but I've re-used them). See what's going on when you slowly pull the rope. Is one valve staying open? If so, try pushing it down when the other valve is opening. Once you get things to start moving, I'd run the engine for about 15 mins, drain the oil, and do that again. You really need to clean things out inside that crankcase if they are dirty. It would not be a bad idea to clean the carb as well.

This basically gets you back to where you were before. Now you need to check for spark and compression. Do you have good spark?
 

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Discussion Starter · #3 ·
Well, based on where the exhaust noise is coming from I think I may have a head gasket problem or maybe a head bolt broke when the piston hit the tester. I am somewhat familiar with larger engines but I've never actually worked on a small engine.

Can you recommend a place to order engine parts from? Is it ok to just order from Sears online for this stuff? I have the original manual that lists all of the part numbers (or at least the diagrams).
 

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I've had good luck myself ordering through Sears on line for my air compressor and a couple other things in the past. I did hear from a guy at work about an order they messed up for him. But I think for the most part they are ok.
 
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