Daniel D
Ok, I'm trying to save money from buying a new lawn mower. I have a snapper briggs and stratton 7HP OHV lawn mower. It is about 8 years old. I had my serviced about 8 months ago, regular tune up. The oil is still good and leveled. The spark plug is a clear blue spark. I emptied and cleaned the fuel tank out. I've been using fresh fuel with a fuel stabilizer. It ran fine for a while. Then it started "acting up". It would run for 30 minutes then die. Then it would start again after priming it then die. So I took apart and cleaned the carburator, jets and everything in it. Gaskets are fine. So the next day I was excited that I cleaned the carburator and hoped my mower would run with no issues. I primed and it took about 3 - 4 pulls then started. I was kind of disappointed that it took that many pulls but it started. It ran longer 40 minutes, sputtered then died. So I re-primed and after several pulls it started and I completed the job. Even though it runs, why does it die after a while? I'm running out of options and patience. Should I just buy a new mower?
Answer
Eight years? You got your moneys worth out of it. But it probably can be made to run properly. Those darn engines are so simple that if you get even a little compression, ignition and fuel they'll run. Hard to kill 'em.
What you are describing sounds like a heat issue. The hotter the engine gets the harder it is to get a proper air to fuel ratio. Remember that hot air is less dense than cold air. You may actually be running rich - as may be indicated by smoking (not oil smoke), or it might not even smoke.
If the engines cooling fins are not clear the cylinder may be over heating and expanding, causing a drop in compression. That's not REAL likely but it can be an indicator of other problems. You could have cracked rings, cracked enough to start but quit after warming up (excessively if that's the case).
Since you've described dismantling the carburetor I'll assume you are savvy enough to disassemble the engine to the point of removing the piston. If you can do that you may find worn or damaged rings that can be the culprit of your troubles. Check the cylinder to make sure it's not excessively worn either. If it has an iron sleeve that's good news; you can hone the cylinder. If not - you would be honing aluminum and probably wasting your time. New rings will likely be in order, and you may want to get over sized rings and properly size them to the cylinder. Normal ring gap is 0.004 inch to 0.007. After honing the cylinder, I'd install the new rings into the cylinder without the piston to get the proper size. If they need to be cut, nearly any automotive supply store should have a ring file. If you don't have feeler gages - get some, you'll need them.
After properly sizing the rings install them onto the piston in their proper position and orientation. Pay careful attention to how the old ones came off and make sure you put the new ones on the same way. Be sure to tighten the end cap onto the piston properly. I'm not familiar with the proper torque, but with a good set of wrenches and a good sense of feel, tighten them. Then bend the locking tabs back over the heads to prevent them from coming loose.
Reassemble the engine. At this point I'm thinking you may have wanted to remove the valves and clean out the carbon. Not a bad idea, but putting those pesky spring clips back in position is rather difficult. You could easily expect to spend an hour just trying to put a single clip back on. THERE ARE proper tools for that job but I've always managed to do it with a screw driver a pair of needle nose pliers and plenty of light to see what I'm doing. Otherwise, if you decide to leave the valves alone, probably not a big deal.
Make sure the cam and crank timing marks are properly aligned, and you didn't loose the valve lifters. They're not held in with anything other than being trapped between the valve stems and the cam. New gaskets would also be a wise move at this point, along with new crank seals. If you're doing that much work why not do it all.
After reassembling the entire engine, make sure there is nothing left loose or left over. There ARE NO OPTIONAL parts. If it was there to start with it should be there when you finished.
For my money, a machine that old, better off donating it to someone who has the time and desire to fix it because they don't have the money for a new machine, and buy yourself a new one. They're not THAT expensive.
Good luck.
")
Eight years? You got your moneys worth out of it. But it probably can be made to run properly. Those darn engines are so simple that if you get even a little compression, ignition and fuel they'll run. Hard to kill 'em.
What you are describing sounds like a heat issue. The hotter the engine gets the harder it is to get a proper air to fuel ratio. Remember that hot air is less dense than cold air. You may actually be running rich - as may be indicated by smoking (not oil smoke), or it might not even smoke.
If the engines cooling fins are not clear the cylinder may be over heating and expanding, causing a drop in compression. That's not REAL likely but it can be an indicator of other problems. You could have cracked rings, cracked enough to start but quit after warming up (excessively if that's the case).
Since you've described dismantling the carburetor I'll assume you are savvy enough to disassemble the engine to the point of removing the piston. If you can do that you may find worn or damaged rings that can be the culprit of your troubles. Check the cylinder to make sure it's not excessively worn either. If it has an iron sleeve that's good news; you can hone the cylinder. If not - you would be honing aluminum and probably wasting your time. New rings will likely be in order, and you may want to get over sized rings and properly size them to the cylinder. Normal ring gap is 0.004 inch to 0.007. After honing the cylinder, I'd install the new rings into the cylinder without the piston to get the proper size. If they need to be cut, nearly any automotive supply store should have a ring file. If you don't have feeler gages - get some, you'll need them.
After properly sizing the rings install them onto the piston in their proper position and orientation. Pay careful attention to how the old ones came off and make sure you put the new ones on the same way. Be sure to tighten the end cap onto the piston properly. I'm not familiar with the proper torque, but with a good set of wrenches and a good sense of feel, tighten them. Then bend the locking tabs back over the heads to prevent them from coming loose.
Reassemble the engine. At this point I'm thinking you may have wanted to remove the valves and clean out the carbon. Not a bad idea, but putting those pesky spring clips back in position is rather difficult. You could easily expect to spend an hour just trying to put a single clip back on. THERE ARE proper tools for that job but I've always managed to do it with a screw driver a pair of needle nose pliers and plenty of light to see what I'm doing. Otherwise, if you decide to leave the valves alone, probably not a big deal.
Make sure the cam and crank timing marks are properly aligned, and you didn't loose the valve lifters. They're not held in with anything other than being trapped between the valve stems and the cam. New gaskets would also be a wise move at this point, along with new crank seals. If you're doing that much work why not do it all.
After reassembling the entire engine, make sure there is nothing left loose or left over. There ARE NO OPTIONAL parts. If it was there to start with it should be there when you finished.
For my money, a machine that old, better off donating it to someone who has the time and desire to fix it because they don't have the money for a new machine, and buy yourself a new one. They're not THAT expensive.
Good luck.
")
Lawn mower loud bang?
Ryan
I buy lawn mower on craigslist for 500 dollar, brand is weed eater, it has 3hp tecumseh engine, it make loud bang after 5 minute of use and i dont know why. it also shoot fire out muffler and then stop. any answer appreciate many time. gracias
Answer
You paid $500 dollars for a used lawn mower. you can buy a brand new one at sears for 300?
Your probably paid for a $500 pos that was broken in the first place. Yet at this point you became a sucker, not only did you buy as is, You can't get your money back the Guy you bought it from, he just has to say it ran fine when he sold it to you.
Lesson here do your home work first, check prices at stores for the same brand before purchase
You could have got the same lawn mower brand new for less? Why would you buy a product that you have no history of? Now your out 500 plus cost for repairs or outright replacement.
Hope that helps
Lr
You paid $500 dollars for a used lawn mower. you can buy a brand new one at sears for 300?
Your probably paid for a $500 pos that was broken in the first place. Yet at this point you became a sucker, not only did you buy as is, You can't get your money back the Guy you bought it from, he just has to say it ran fine when he sold it to you.
Lesson here do your home work first, check prices at stores for the same brand before purchase
You could have got the same lawn mower brand new for less? Why would you buy a product that you have no history of? Now your out 500 plus cost for repairs or outright replacement.
Hope that helps
Lr
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