QuestionQUESTION: Briggs & Stratton Model-311777, Type-0143-E1, Code-000602ZD. My question is how can I tell if only rings need to be replaced, or if I need to have a cylinder that needs to be reworked/replaced?
First the problem that caused a bigger problem was an electric fuel shut off that was stuck open. This flooded the carb, filled the cylinder with fuel and bound the engine when it tried to compress a cylinder full of fuel. With heavy pressure on the fan-flywheel I was able to manually turn the engine, but I was just pushing fuel past the rings. So I solved that problem with a new solenoid fuel shut off plus a manual in line shut off, but I think I have damaged the rings or cylinder.
After replacing oil and filter a couple of times to clean out the engine, the engine smokes quite a bit with new oil, and after about 30 minutes of use it smokes severely, and seems to loose some power. When I check the oil the level has risen about an inch over full with fuel that has made it into the crankcase. I have been through this cycle twice. So it looks like I have some engine damage to repair. How can I tell if this is just a need for new rings, or a new cylinder assembly, and what else do I need to look out for that I may have damaged?
ANSWER: Your real problem is that the needle in the carburetor isn't seating. The solenoid is to shut the gas flow off when the key is turned off, preventing backfires. It has the added benefit of preventing fuel from leaking into the engine if the needle sticks when the engine is off, but it's the needle that's failing causing your problem.
You may have gotten lucky in that it's the rod that fails when this problem occurs. The gas breaks down the oil wedge/bearing and the rod overheats and fails, often going through the side of the block.
I'm going to assume that you have a lot of white smoke? This is probably from the oil thinning and making it past the crankcase breather, rings, valves and into the combustion process.
You probably won't have a ring or cylinder problem and you may have caught it in time before there's any rod damage. Rebuild, or better yet, replace, the carburetor. If it has the Nikki carburetor, I toss them 100% of the time. If it has the Walbro, I probably scrap them about 75% of the time.
This is a very common problem with these engines and we replace or rebuild a couple dozen every season. Let me know if you have any questions. Thanks, PK.
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QUESTION: So I replaced the Walbro carburetor, but this has not completely solved the problem. I still have a lot of white smoke. When I thought I was just burning oil out of the muffler, the engine used about 1/4 quart of oil in 30 minutes. To make sure that I was not just burning oil out of the muffler, I ran the engine without the muffler for a few minutes. After the engine runs for about 30 seconds I get heavy smoke even without the muffler. Your thoughts here?
There new oil that I put in the engine quickly blackened and had a slight gas odor. Would this be residual fuel/oil from the previous gas that got into the crankcase. If so how would I get it out other than frequently changing the oil a few times?
According to the parts manual the carburetor part number was 698620. However, that number has been replaced by 791886 which is slightly different. The 791886 has a spring putting pressure against the side of the choke control arm that does not allow the choke to move freely, and you have to manually pull the choke off at the carburetor instead of just pulling back on the mower's throttle control. Is this a part that fits multiple applications, and the spring just needs to be removed, or does this sound like the wrong part?
Finally, I cleaned all of the old oil and gas out of the breather, and it moves freely and is within tolerance. Under ideal conditions should the breather assembly stay completely clean or should it have some oil on it?
AnswerYou'll probably need to change the oil a couple of times. The breather may also be allowing too much oil to pass as well. If there's oil in the air filter housing, then the breather will need changing. Usually a lot of white smoke is the breather. A little smoke or blue smoke would be bad, but a lot of smoke usually isn't.
That's the correct carburetor replacement. I'm not sure offhand how yours is set up, but removing the spring is nothing more than removing the butterly for the choke and pulling the shaft out and taking the spring off.
