12Q802 B&S Engine

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Old 05-31-10, 04:51 PM
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12Q802 B&S Engine

I have a customer who has a 2004 Craftsman 6.25 hp selfpropelled push mower with a B&S 12Q802-0252-B1 engine. He says it smokes and wants a ring job. I have yet to look at it, but I am leaning towards telling him to buy a new engine. The replacement engine for this is $150. Parts & labor for me to do it is more than the replacement cost. I will have it here tomorrow. Hopefully, it will be an easy fix such as overfilled with oil, or a blown head gasket. What are your thoughts on that engine?
 
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Old 05-31-10, 09:11 PM
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Sure you will have a much better idea once you see it in action. If it is one with the primer in the air filter housing and a plastic intake pipe...those I have seen issues with but otherwise seem to be good engines as little as I have used them. Not had a return on repairing one though.
 
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Old 05-31-10, 11:11 PM
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Usually the cylinder walls are shot too. I don't rebuild those engines, like you say, the parts and labor is more than it's worth.
 
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Old 06-01-10, 12:13 PM
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Got it in the shop today. It is primer only. Oil level just above add. Primed 3 times. Nothing. Primed 3 more times and it starts. Blowing a big cloud of white smoke. Nice mosquito chaser. Let it run for 3 mins to see if the smoke calms down. Nope. Shut it down and check the air filter. Clogged with grass, leaves. Removed the air filter. Started again. Smoked heavey for about 30 seconds then died down to constant little smoke. Pulled the spark plug. Gray. Compression 70lbs. Thinking smoke may have been from over priming and needs carb cleaning. Should only have to prime 3 times. I was thinking head gasket, but with 70lbs compression, no.
 
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Old 06-01-10, 07:00 PM
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Originally Posted by indypower1 View Post
Got it in the shop today. It is primer only. Oil level just above add. Primed 3 times. Nothing. Primed 3 more times and it starts. Blowing a big cloud of white smoke. Nice mosquito chaser. Let it run for 3 mins to see if the smoke calms down. Nope. Shut it down and check the air filter. Clogged with grass, leaves. Removed the air filter. Started again. Smoked heavey for about 30 seconds then died down to constant little smoke. Pulled the spark plug. Gray. Compression 70lbs. Thinking smoke may have been from over priming and needs carb cleaning. Should only have to prime 3 times. I was thinking head gasket, but with 70lbs compression, no.
Don't those blown head gaskets sometimes give decent compression and then leak when it's heating up.
 
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Old 06-02-10, 01:16 AM
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It's a flathead engine, a blown head gasket won't cause smoking on it. Are you thinking 70 lbs compression is good?
 
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Old 06-02-10, 08:18 AM
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I don't rely or even check compression often but I like to see closer to 120 at least, 80 a bare min.
Could try a squirt of oil in the cylinder and see if the reading improves...that would show rings or cylinder wall as cheese suggested.
 
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Old 06-02-10, 04:53 PM
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Originally Posted by cheese View Post
It's a flathead engine, a blown head gasket won't cause smoking on it. Are you thinking 70 lbs compression is good?
No, not thinking it is good, just stating what it has. Not going to do anything else to it. Just going to tell him to look on Craigslist for a used mower.
 
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