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  #1  
Old 06-10-03, 06:04 PM
raymo8
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Lawn mower that won't start...

Craftsman Riding Mower
12.5 hp Briggs & Stratton
7 years old

I can't get the engine to start. The starter is spinning the flywheel strong but it won't fire up. There was definitely a spark when I tested it too. I sprayed quick start engine fluid in the spark plug hole and air filter hole, neither worked. I also checked to see if the fuel filter was clogged and that the float bowl was clean, both are fine. I'm out of ideas at this point. Does anyone have any suggestions? Thanks.
 
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Old 06-10-03, 11:31 PM
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Hello Raymo8!

Does the engine have compression?
 
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Old 06-11-03, 04:03 AM
raymo8
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lawn mower that won't start...

How do I check for compression? THanks.
 
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Old 06-11-03, 06:29 AM
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Hello raymo8

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  #5  
Old 06-11-03, 08:06 AM
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First off, if the engine has compression, you would feel a resistance when turning it over, such as when you start any small engine. If it spins over effortlessly with out resistance, then that is a sign of low compression. Another way to check is to remove the spark plug and stick your finger over the hole for the plug and spin the engine over. You should feel a suction on your finger and then you should feel air being force out of that hole, enough to where it would start to push your finger off of the hole.
 
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Old 06-11-03, 05:25 PM
raymo8
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Mower17,

I tried the compression test tonight. It seems that you and Cheese are right when you say that there may be no compression. The flywheel turns easily by hand (not extremely easy but a lot easier than I used to remember in its younger days). If this is the problem, then I have two questions. First, why would low compression cause it to not start? And second, what should I do now to fix this? Thanks.
 
  #7  
Old 06-11-03, 07:44 PM
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You might have a stuck valve. To check this, remove the little valve cover on the side of the engine. This cover is the small 2"x1" rectangular cover located not far from the muffler. Once this is removed, turn the engine over and see if both valves move back and forth. If one of them doesn't, then that valve is stuck. To fix this you would have to remove the head and the valve and clean it up. Did the engine sit for a while without running? This would usually cause a stuck valve.
 
  #8  
Old 06-11-03, 10:21 PM
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Another possibility would be that the engine has broken a rod. If the piston does not move back and forth when you turn the engine, then the rod is broken and the engine will need to be disassembled to determine whether or not it is rebuildable.

If the engine suddenly quit running, I would tend to think you have a broken rod. If it has been sitting up for a while without being used, I would lean toward the stuck valve as mower17 mentioned.
 
  #9  
Old 06-13-03, 10:04 AM
raymo8
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Hey guys,

You were right! One of the valves was stuck open because the washer type ring around it had somehow come out of its seat in the engine block and jammed the valve from being able to go back in. I put the ring back into its seat and everything is working great again. It started right up and I have the compression back. Thanks. You guys are good, this is the second time that you gave me the right answer!
 
  #10  
Old 06-13-03, 11:33 AM
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Glad you got it going! One thing though...the seat will come back out. You will need to peen it in with a punch to make it stay in place. This link shows a picture of a valve seat that has been installed in this fashion: http://cgi.ebay.com/ws/eBayISAPI.dll...category=20544
 
  #11  
Old 06-21-03, 05:54 AM
raymo8
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Cheese,

Unfortunately I put the whole thing back together before I read your response about peening in the ring. So, as anticipated, the ring popped back out the other day. I just took the cylinder head off again and want to make sure that the ring stays in this time. I know that you said to peen it in there with a punch and I saw the picture, but I'm still a little confused on what to do. Do I punch the metal block around the ring to make a bunch of shallow holes that bend the metal in to hold the ring? The ring is real loose at this point so I need to figure out a good way of keeping it in there. Thanks.
 
  #12  
Old 06-21-03, 11:07 PM
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That is exactly what you do. Doing so will make the metal overlap the seat, keeping it in place.
 
  #13  
Old 06-23-03, 12:18 AM
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Yep....peen the aluminum of the engine right next to the valve seat to make that metal spread enough to hold the seat in place tight. Just don't crack the seat!
 
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