QuestionEric, I have a Kohler MV18 on an Ariens HT18 garden tractor. Roughly 1994 and well taken care of. Recently it failed to start, and after replacing and properly gapping the coil it started fine and ran all summer...Now I'm using it for snow, and it would not start a couple weeks ago. A fully charged battery still didn't help. I was ready to give up, and decided as a last resort to jump it at what I thought would be an excessive 20 amps from a charger. The difference was immediate and it ran great for a few days, but still only started by requiring the charger as a boost each day I used it. Now it is a few weeks later, and even with the boost and a fully charged battery, it won't start. It has spark at each plug, and the needle shows about 14v before I turn the key. With load on battery it still exceeds 10v as it cranks over. Spark presence tells me coil is okay. Could the rectifier be bad? Did I fry it? The stator? Flywheel key? Any ideas? One hint may be that with one spark plug removed, I cranked it and it almost started. Why? And what might that be indicative of? Plugs are new. No idea when or if valves were ever adjusted. The tractor seems too clean to have been neglected. Help me please!
AnswerCold temps do not help the CCA of the battery. While 10 volts sounds sufficient it may not be enough...but with the battery charger it should be plenty.
I doubt you fried the regulator. You can find the service manual at the URL below:
http://www.kohlerengines.com/onlinecatalog/pdf/tp_2289_a.pdf
Section 8 describes how to check the regulator.
Have you disconnected the battery cables and cleaned the battery cables ends and battery terminals with a wirebrush. You may not see any corrosion but I have fixed a lot of hard starting problems just by disconnecting and cleaning the battery connections.
I rarely find bad or weak starters but it can happen. I did not see any starter current draw specs in the service manual. If you suspect a weak starter I would contact a local automotive electric rebuilder in you local area and see if they can check the starter and how much it would cost. We don't bother rebuilding starters...we either buy new ones or have a local auto electric shop rebuild the starter depending on the application and cost of a new one vs rebuilding.
I have had issues with old battery cables. While rare, I always check the voltage drop across each section of each battery cable, positive and negative. Measuring the voltage is a quick check for determining the condition of cables as well as identifying poor ground connections.
I am assuming you have a voltmeter since you mentioned the 10v. Do some searching on measuring voltage drop...very handy when used correctly. I typically repair all electric issues at the shop as I am well versed in voltage drop theory and practice. Most problems can be identified in less than 15 minutes if you know how to use you meter effectively. BTW, I rarely use the current (amp) measurement feature of the meter...voltage and voltage drop tells me everything I need to known. If all the cables, connections and grounds are good odds are it is either the starter or a mechanical issue such as valves or compression release. You might find a weak or faulty solenoid once in a while but I have also found poor, too small or old, solenoid exciter wiring cause the solenoid not to fully close and not allowing all the battery power to reach the starter...that took a while to solve...ran a new, larger wire and never saw that Snapper mower again!
Finally, have you had the battery load tested at you local auto parts store to ensure it has sufficient cranking amps?
Eric
