John Deere JD L-120 w/ Briggs V-Twin Intek

"Tractor" is little misleading... in fact in my son's book about tractors (he's 2-1/2) they refer to these lawn tractors as "mini-tractors". Regardless, it has a 20 HP Twin cylinder Briggs and Stratton V-Twin Intek engine.  The previous owner bought it new and threw it into the deal when we were negotiating the purchase price. From the looks of it there was little to no maintenance ever performed on it, and it was parked behind the garden shed with no cover from the elements. Manual for this model can be found  HERE., and illustrated parts diagrams & listings are HERE.

Briggs V-Twin Intek Engine ID#

So after using it for 1/2 mowing season last year, things started to break down on it. Here's the list of repairs I've made to it so far:

• Oil Change with new oil filter
• Replaced Fuel Filter
• Replaced Air Filter
• Re-built starter (Replaced end cap/brush assembly)
• Replaced starter solenoid switch
• Replaced Battery

As you can probably gather from the above list - the majority of the issues I was having with it was starting it up. I made a lot of mistakes while diagnosing and repairing the problem, but of course hindsight is 20/20. Here's a recount of my crash course on small engine repair.

First issue I came across was having to use starter fluid to get the thing to fire up EVERY TIME. This is obviously not a good thing. Some quick tidbits I learned regarding starting fluid -  it is important to spray this into the air intake. I'll be honest - it took me longer than it should have to figure out where the air intake was. I know I personally sprayed starter fluid into the top blower on the engine, as did my wife. Another note on starter fluid - only use a little bit. From the looks of the air filter and air filter housing, at some point too much was sprayed in and there was a fire or flare up within the air intake chamber - burned filter, melted plastic, etc... [UPDATE 10-31-12 - The flare up or fire I referred to above is most likely the result of an engine backfire through the carb, inside the air intake chamber. I saw a video of this backfire in action here HERE.] I don't see any problem in using starter fluid, but it is certainly a symptom of a problem of some sort if it is the only way to get the engine going. 

Even with the starter fluid, I would have to crank and crank the engine to the point that the battery cable connected to the starter motor got so hot the insulating jacket started to melt (and smoke!!!). My guess was gas not getting to the engine, so I cleaned the fuel pump and replaced fuel filter (VERY EASY). I was able to get the fuel filter replacement at the local Tractor Supply. Problem solved.

Next issue - when I went to start her up I would hear a click then nothing. No turn over, no endless cranking, just nothing. Hmmm... must be the battery. It was pretty old so I went ahead and replaced that. Still nothing...

Ok, then maybe the starter is bad. The previous owner had attached the cable to the starter in a way that required the nut to be tightened and led to the bottom end cap breaking and exposing some copper wire. After buying a new end cap, I realized there was supposed to be TWO nuts at this attachment, so that you did not have to tighten the one closest to, and attached, to the end cap in order to tighten the cable. However, what I assumed was that the broken end cap was resulting in the starter not engaging. Mistake #1. 

So I went about figuring out how to remove the starter. This is a very involved process. Why they make it so hard to remove I have no idea. Ridiculous really, but nonetheless - you have to disassemble the engine so you can remove the flywheel, and that's only the start of the adventure - removing the flywheel is a whole other ordeal. First - to get to the flywheel you have to remove the blower cover, air filter cover, and remove the "shroud" that cover the flywheel and blower. In order to get the shroud off you have to also remove the vacuum fuel pump. As per everyone's instructions, I disconnected the battery and unplugged spark plug wires prior to doing any work. Ok - once you have removed the bolts for the shroud -  or in my case removed most and broke one (dammit!) you can remove to reveal the plastic blower thingy with a bunch of fins attached to the top of the flywheel.  This comes off with two bolts pretty easily.

View of blower with shroud removed.

Once removed the nut and washer that holds the flywheel down to the block will be exposed. Remove the iginition coils (or magnetos) so you don't damage them when removing the flywheel. These little fellas are surprisingly expensive. 

Now to remove the flywheel...

Very difficult, very difficult indeed. You have to loosen a very difficult bolt first. In order to "lock" the flywheel to allow this nut to be loosened, you can either use a flywheel lock tool sold for Briggs engines, use an air wrench like you'll see most people do on YouTube, or do like I did and follow some great advice by DonyBoy on YouTube, which was to remove spark plugs and stick lengths of nylon ropes into the spark plug openings on the cylinders. Flywheel will rotate maybe 1/2 or 1/4 turn and then won't go any further. I almost blew an O-ring - one of mine that is- when loosening this nut... man was it really on there. Once I got it loose, removed it and the washer below. Now I thought with the nut off I would be able to just pull the flywheel up to get it off. WRONG!! Removal involved banging on the crankshaft with a mini-sledge while simultaneously prying it up from below with a pry bar to get it to "pop" up and then you can remove by lifting it off. I know banging on the crankshaft is not a good idea or recommended by anyone in their right mind, but with no briggs flywheel puller and accompanying air impact wrench, what are you going to do? Be careful, as the magnet and a lot of sharp items very close to the flywheel make this a repair that will probably leave a mark... The lesson learned here was that the flywheel fits down onto the shaft, then has a small metal insert called a Flywheel key, that slides into the flywheel key slot, and the whole thing relies on friction to hold it in place. This came into play a little later on... For those of you who are clueless when it comes to small engines like me, please note that the flywheel contains both a magnet on the edge, and then many magnets underneath. This was somewhat of a surprise for me when I set it down on my work bench full of metal pieces :) 

Alternator exposed once flywheel is off.

Ok, now that the flywheel is off, I had to remove a metal cover bolted to the block that protects the underside of the flywheel and also around the top of the starter. This came off easily with (4) star head bolts/screws. With this cover off, I could now remove the starter.... Whew!!! Again, I have no idea why they make this part so difficult to remove. 

Next I took the starter off and went about taking it apart. Thanks to fnaguitarplayer9 on YouTube for some top notch how-to's on re-building all varieties of Briggs starters. I replaced the end cap with all new brushes, cleaned up the armature,  greased the bearings, and tested it. The plastic gear at the time was a little chewed but was still usable, so I left it on. I would take pictures of this as you take it apart, I had to go back and watch YouTube many times to remember which washers went where... Also - the flying c-shaped retainer you see in fnaguitarplayers video also happened to me. However, instead of bouncing around my garage it went straight out the window right above my workbench. What are the chances - right? Anyway - this is not a piece I was able to find locally, but I did find a pretty good substitute. The "snap ring" assortment they sell at Autozone has a 1/4" version that worked out well with a little modification. I snipped one of the round ends off the snap ring and it fit perfect. I'll post a picture if I remember...

Now, back to Mistake #1. I assumed that the starter was bad due to the lack of anything happening when the key was turned. When I started the diagnosing of this, I had no idea what the phrase "Jump across to the starter" meant. Had I known how this works, I would have used my jumper cables to connect the hot side of the battery, then connected the negative cable to the negative post on the battery and the other negative end to something metal, and when I touched the other end of the hot cable to the nut on the starter - voila! - I would have seen if the issue was in the starter. Well, I did not do that because I had no idea that it was this simple to test, or really that the whole ignition system was so simple. Had I done this, I would have most likely realized that the starter, although a little worse for the wear, was still operational, and my problem was somewhere between the battery and the starter. That leaves only 3 options - cables (not likely unless severed, broken, or extremely corroded contacts), Fuse (20A, very easy to remove/check), or the starter solenoid switch.

Now, to continue on with the flywheel, as there is so much more to that story (sadly)... So I get done testing the starter, and she's running like a champ. I put it back on the block and then start putting it back together. I looked at the flywheel shaft and decided it could use some maintenance. So, like a good mechanic I put some grease on the shaft and bearings, looked at the flywheel key which seemed good to me, and then proceeded to put it back together. Put the washer on, tightened the flywheel bolt etc etc. So, expecting some magic, I jumped on and turned the key - nothing. Just a click and nothing... DAMMIT!! So now I'm pissed. But, I now know how to jump across the middle man (starter solenoid) to the starter. When I did this she fired right up!! I was pretty pumped, as was my daughter and youngest son. It was a great celebration in the driveway - one I'm sure to remember forever. The celebration was short lived however. After letting it run for about 3 minutes, I figured it was time to get to the mowing. I pulled into the yard, engaged the PTO, and was off to mowing. About 1 minute or so into mowing I noticed the engine starting to have trouble... sputtering and really sounding awful. I kept her rolling along to see if it was just bad gas or maybe I flooded the engine or something like that, but it got worse and worse and finally culminated in a sputter-sputter-die complete with a puff of black smoke. I looked up to see my wife on the back porch giving me the "Awww, it's ok" look... She's really great like that. The kids looked at me with the same "it's ok Dad" look - I really love how much they worry about my mental state. This concern was short lived, as my daughter succintly stated it was time to take it to the repair shop. She's pretty sharp for a 7 year old! Defeated, I went about recreating the failed attempt -  What the heck just happened? I tried starting it again and it was acting like the flywheel was hitting something and then stopping, like it couldn't go all the way around. Back to google for some diagnosing. Had a hunch it was something with the flywheel, as that was really the only critical engine part I touched. 

After a little reading, figured I should take it back apart to look at the flywheel and iginition coils, maybe I messed up the spacing on these. According to manufacturer it should be .010mm, or width of business card. I thought maybe I installed them back to close, and they were contacting the flywheel causing it to not spin freely.

Once I got it apart it became clear what had happened. Flywheel key was sheared in half, causing engine timing to be totally out of whack, hence the sputter-sputter-die-poof scenario. But what caused the key to shear? I don't remember hitting anything with the mower... more reading... came across a little nugget on some small engine discussion thread that provided the key piece of information. The flywheel fits onto the shaft via friction, so when I greased the shaft and bearing, it prevented this vital friction coupling from taking place, and allowed just enough "play" to cause the flywheel to move independent of the shaft and shear the key. Turns out these keys are designed to be sacrificial lambs, in case something causes the crankshaft to stop and the flywheel wants to keep going, which if rigidly connected will undoubtedly cause some damage to the crankshaft,  flywheel, or both. From what I read if the crankshaft is damaged, you may as well look for a new tractor as the engine is toast. So, after ordering some replacement keys and waiting for them to arrive, I cleaned all the grease off the shaft, and inside the flywheel. I also made sure there was no damage/scarring/burrs from the shearing, and satisfied it was free and clean I set the flywheel on. If I didn't mention this before, watch your fingers when lowering the flywheel down onto the block. The magnets on the underside of this bad boy are really powerful, so once it gets close to the block it will suck it down with some serious force - OUCH! Once the flywheel was on I lined up the keyway slots, and inserted a new key. I tapped the flywheel down somewhat gently, then tapped the key in until just snug, replaced the bolt and washer, tightened it as tight as humanely possible, and proceeded to put the whole thing back together. Finally, I changed out the starter solenoid with a new one.

Once all back together, I turned the key and she fired up immediately. Not sure how I could have helped the hard starting as I did not repair the carburetor or adjust the valves, but hey, I'll take it. I was nervous when I first engaged the PTO, but so far so good. The engine firing does still sound a little off, and when at low throttle sounds like she wants to die out, so next I'll be looking at cleaning/adjusting the carb and also will adjust the valves. Both of these repairs will of course be documented here, if for no other reason than to show how completely ignorant I am of engine repair, but how willing I am to sacrifice my poor John Deere to learn!