QuestionHere's what I found:
Starter clutch: I wasn't going to buy a new clutch for this old mower. I didn't know that I could easily remove the plastic lid that covers the workings. This was the first time that I saw the inside of a starter clutch. It was totally dry in there, and the balls were either "rust-welding" to the outer part of the clutch or were sticking due to some old sludge. I saw that the mechanism relied on gravity to pull the balls back down as long as they weren't sticking to the outer part of the clutch. So, I cleaned out a tiny bit of sticky old grease, and put in a little light oil to keep balls from sticking to the sides. The clutch didn't catch once after this, but that was easily corrected by a gentle tap with a hammer.
Intermittent spark: I didn't quite understand what you were saying about this. I didn't think that the cut-off switch was the problem. After experiencing this problem 2 more times, I examined the engine cut-off mechanism. I hadn't known that there was an electrical wire going there to short the circuit. I thought that the flywheel clamp just mechanically stopped the engine. Anyway, it took me a while to see what was what, but once I understood how it worked, it looked to me like the metal contact from the wire was touching the cut-off link when the handle lever was fully pulled. I looked for a way to adjust the cable and couldn't find one (which seems ridiculous). Now I understand what you're saying about drilling a new hole in the handle, and remounting the upper part of the cable. Instead of that, I bent the cut-off link so that it wouldn't touch the electrical contact when it shouldn't. I think that this was the problem, though it will take time to ensure that the problem doesn't recur.
I had told you before that I wasn't getting spark, and then I would get spark after taking the flywheel cover off, or even just messing with the cable retaining screws. I was stymied as I couldn't figure out where a short could be! I finally examined the cut-off mechanism today because I was intermittently getting spark without doing anything! It was driving me crazy. Moreover, today, when I did get it started, it would idle fine, but would run roughly, missing and sputtering when throttled up. That made me think that there was another problem, like maybe the carb! I was about to give up on this mower. I now believe that the cut-off wire was barely touching the link, or arcing to the link, so that I'd get intermittent spark at the plug, and even get uneven running due to intermittent shorting when the engine was going fast enough, perhaps due to vibration. Once I bent the cut-off link, the mower ran fine. I thought that I'd mention this to you, as I never would have guessed that this would be the cause if the only problem was erratic or rough engine performance; if it weren't for the intermittent total lack of spark, I'd never have looked at the cut-off switch as a possible cause. I'll never forget this experience and will always check the cut-off switch--or possible short elsewhere--if I experience either problem with any small engine in the future.
You were dead on in your diagnoses. Thanks a lot. However, I like my fix of the starter clutch better than yours. Also, I think that you assumed that I knew more about the cut-off mechanism than I did because I didn't understand what you were saying, and that delayed my discovery and fix of the problem. I thought that the cut-off mechanism was purely mechanical, not electrical. I was pretty ignorant to think that that clamp on the flywheel is what killed the engine when the handle lever is released.
Thanks again,
Scott
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Followup To
Question -
Hi,
This regards a push Lawn Chief mower with a 3.5 HP B&S engine. I cleaned and performed maintenance on this in preparation to sell it. Twice, it has been impossible to start for 2 different reasons that cleared up without a diagnosis. I don't want a buyer to return in a week saying that it doesn't start, so I'd like to diagnose and prevent these 2 problems from recurring.
1. I tried to start it once, and the starter pulley/clutch (The thing that screws onto the spindle, above the flywheel; I don't know the terminology.) wouldn't engage no matter what I did. This was not a problem with the part that the rope goes into; it was the part that screws on the spindle. I finally unscrewed it from the spindle, and found that it then miraculously engaged in the right direction, when, before, it would freely spin in both directions. How can I prevent this from happening again? If it does happen again, can it be rectified without being unscrewed from the spindle?
2. I had the mower out at a yard sale. I had started it that morning to ensure that it would start easily, and had no problem. In the afternoon, I tried to start it for a potential buyer, and, embarrasingly, it wouldn't try at all. I later found that it had no spark, so I took off the flywheel cover to see if I could see any problem. I didn't see anything amiss, and since I don't have a flywheel puller, I felt stymied. I tried a different spark plug and got fire. Then, I found that the original plug was sparking too. I reassembled the cover, and got no spark again! I then unscrewed the two 5/16" head cable screws that screw into the cover, and found that I was getting spark! I screwed them in and got no spark one time, and got it the next time I repeated unscrewing and rescrewing them. I could see no reason for the spark plug wire, or any other wire, to be short circuited (the wire was not crimped by the cover). The mower now runs, but I'm afraid that this undiagnosed problem will recur when a buyer shows up or a week after he buys it. Have you ever run into this?
One last question while I've got you: I'm scared of damaging the flywheel or any parts under it if I try to remove without a puller (as a teen, I used to use a big screwdriver to pry it off in a jerky fashion). I don't mess with mower engines often, but, when I do, I feel that not being able to get the flywheel off is a major limitation. Do you feel that it's safe to take flywheels off without a puller?
Thanks a lot,
Scott
Answer -
As for the starter clutch not catching, replace the starter clutch. The 6 small balls inside the clutch sometimes stick to the outside of the clutch allowing it to spin freely in both directions. You can take the clutch apart and clean it but there is generally some wear on the lower starter clutch housing and the problem can happen again.
As for the spark, the engine shut-off cable could be stretched just a little. I've had the cables stretch where you could pull the string but had no spark. A simple,cheap and effective fix it to drill another how just a little lower on the handle to lower the orginal mounting position of the cable retaining screw...just use the lower hole to retain the cable.
As for the puller, I've been told you and crack the flywheel without using a puller. After breaking some cooling fins I quickly invested in the pullers...makes the job 10 times eaiser...especially if the key is sheared.
Let me know what you find.
Eric
AnswerSorry I wasn't more clear about the shut-off switch but I sometimes take for granted others experience. I've found very few adjustable shut-off cables...I think the manufactures would prefer if you purchased a new one.
As long as you know about the starter clutch I wouldn't replace it. We do not oil starter clutches at the shop because the oil just collects dust and the balls stick to the side again causing the same problem. Customers complain about the price but they also complain if they have to bring the mower back to the shop for the same problem. Briggs used to say never oil the clutch but recently they changed their policy and said you could use strait 30W synthetic oil. Easier sad than done...not to many places sell the oil.
Glad to hear you got the mower running.
Eric
