Here's what broke on my 4cycle Troybilt trimmer

what's going on everybody and thanks for stopping by today's project is this string trimmer and the problem is that it broke in the last video when I was trying to repair it today we're going to open the engine up and see if we figure out what happened to it now this is not a repair video so I'm not worried about putting things back together however if you're still interested I will show you the majority of the disassembly process in a previous video we were spinning the engine over when all of a sudden we lost all resistance from the engine a musher how or why but we lost all inch compression very quickly you'll protect the spark plug out we can see that the tip has made contact with something more than likely the piston as you can see the resistance from the pull rope is basically the same as before even without the spark plug being in so let's start by taking the plastic covers off starting with the top cover now the fuel lines are still attached to the primer bulb and we're going to need to remove them but first let's take the filter base off this will help us figure out what lines go where just in case we need to work on another unit like this in the future we're gonna have to remove almost every piece of plastic cover on this engine just to look at the connecting rod and if we need to we'll also remove the top part of the engine to look at the piston now take off each line noting where each one goes I've never had to deal with a primer ball that has three ports on it so this is for my education as well as yours now once all that's done we can now remove the carburetor from the engine next thing your move is the recoil assembly but before we move on let's string the oil out so we don't make a mess we remove the oil pan well there's definitely plenty of oil in the engine so I don't think it failed because of a lack of lubrication although it is a little bit dirty though before we can take any more plastic pieces off we have to remove a rivet that connects the recoil assembly to the muffler cover now the recoil assembly is in great working condition and it'll be kept for parts just like the rest of the parts that's coming off of this engine when removing the fuel tank make sure you keep the rubber grommets otherwise the fuel tank will be loose when you install it in another unit I did want to take a little break and show you that the connecting rod is still connected to the piston and in one piece so if I put a screwdriver in the spark plug hole and turn the engine over I can feel the piston moving up and down so we know that that's not the problem but I still want to take the oil pan off to take a look around so the pan bolts have a lot of Loctite on them so I'm gonna break them loose by hand before using my drill now the oil filled tube is kind of in the way so we'll have to remove it so we can get to some of the other bolts that are underneath it I'm not really sure at this point if the fan needs to be removed to allow the pan to be slid off of it but let's do it anyway I had to take a large allen wrench and grind it down with my grinder to have five sides instead of six and then put it on the JumpStart shaft so to keep the engine from spinning I had to wedge a very large screwdriver on the flywheel side of the engine as I turned the JumpStart side then use an impact to take the JumpStart shaft off which is threaded on to the crankshaft well it looks like I didn't really need to do that because what I thought was a crankshaft was actually basically a PTO shaft off the backside of the engine so here's the rotating assembly and everything looks just fine it spins like it's supposed to but it wants to stop near the top of its travel so there's something on the other side of the piston so here's a look at that PTO on the oil pan this is a pretty smart setup as it doesn't connect directly to the crankshaft then should save a lot of time on the assembly line so to remove the top part of the engine we've got to remove the plastic piece on the intake side of the engine as well as the muffler and after that we can finally remove the four bolts that hold it to the block okay so here's the piston and to get a better look at it I'll clean off some of the oil wow this is really bad so it looks like part of the piston broke off and basically destroyed the entire engine so the debris basically gouged the side of the piston and the cylinder wall resulted in a major loss of compression I'm also sure that the debris is also embedded in the valve seats as well so if I had to guess the piston broke and closed the spark plug gap and stop the engine immediately then when I was spinning the engine over with the electric jump starter the debris inside the engine destroyed the cylinder wall and the piston that's why I had an immediate loss of compression as for root causes Y the piston broke I couldn't really tell you but if I had to guess I'd say that it leaned out at wide open throttle and the cylinder temperatures got too high and melted the edge of the piston and then destroyed the rest of it so my question to you is what do you think happened to this engine you agree with me or do you have another idea I'd like to know what your thoughts are thank you for watching I really appreciate your time please feel free to ask any questions and I hope to see you in my next video

Channel: INSIDE HOUSE GARAGE

Views: 6,012

Rating: 4.8333335 out of 5

Keywords: troybilt, troy, echo, husqvarna, stihl, murray, ryboi, toro, weedeater, trimmer, strimmer, string, grass, weed, trim, 4cycle, cycle, stroke, broke, blown, rebuild, jug, cylinder, piston, ring, damage, damaged, scoring, home, garage, inside, house, watch, before, you, buy

Id: _dOJoSAt8NM

Length: 8min 0sec (480 seconds)

Published: Sun Jun 16 2019