longjohn119
Cadet
- Joined
- Jun 22, 2009
- Messages
- 20
Shortly after rebuilding the carb in hope of making this unit cold start easier I was running full throttle when the engine started missing and on easing down the throttle completely died and wouldn't restart. Of course I figured it was something I had missed when doing the carb rebuild but after removing, disassembling, and remounting the carb 3 times and not finding any faults, I did some tyroubleshooting on the electrical side finding a weak ignotion coil on the bottom cylinder but after replacing it still no start. I suspected a reed problem and isolated it after squirting mix into the carb but getting no start and then squirting mix into the cylinder through the sparkplug holes and getting it to fire and die so obviously I wasn't getting fuel into the cylinder after the carbs. Tearing down the block revealed a broken reed block, and a cracked reed stop. Luckily none of the reed block pieces got into the cylinders or caused any other damage to the crankcase except the holding pin hole for the reed block on the cylinder side had egged out. I found a used reed block and have a couple of questions on repair
1. First and foremost I need to take care of the egged out hole for the holding pin. Would good ol' JB Weld and a jig to align the pin until it sets up do the trick? (Keep in mind it's a 33 year old engine that I paid $300 for)
2. Is there anything I can put on the cylinder side of the block to help hold the reed block in place and take some of the pressure off the JB Welded holding pin?
3. I don't exactly trust this Seloc manual, what is the best product to seal up the crankcase
4. Any other tips that might be relevant, again keeping in mind this is a 33 year old $300 motor (In other words putting in $300 worth of parts isn't feasible or very reasonable)
A less important question but one I would still like to answer and is directed more at you guys that work on Mercs for a living. I rebuild/replace large commercial refrigeration compressors under warranty which are very similar in nature to a two stroke motors. One of the things I have to do for warranty is do a failure analysis to help engineering locate any faults/weakspots in the design and manufacturing process so I would like to understand the 'failure mechanism' here. Personally I suspect the left top reedstop came loose and 'chattered' causing the initial crack to form around that screw hole causing the reeedblock to break away from the portion with the holding bolt going through the bottom cover of the crankcase. Since most of the reedblock was then floating it caused the pin on the block side to egg out. BTW I checked the crankshaft end play and it was OK. Also the motor was never over revved in neutral which I'm not sure is even possible with this motor due to the way the trottle and shift linkage is designed. I enclosed a few pictures of the reed block so you can see the damage yourself
1. First and foremost I need to take care of the egged out hole for the holding pin. Would good ol' JB Weld and a jig to align the pin until it sets up do the trick? (Keep in mind it's a 33 year old engine that I paid $300 for)
2. Is there anything I can put on the cylinder side of the block to help hold the reed block in place and take some of the pressure off the JB Welded holding pin?
3. I don't exactly trust this Seloc manual, what is the best product to seal up the crankcase
4. Any other tips that might be relevant, again keeping in mind this is a 33 year old $300 motor (In other words putting in $300 worth of parts isn't feasible or very reasonable)
A less important question but one I would still like to answer and is directed more at you guys that work on Mercs for a living. I rebuild/replace large commercial refrigeration compressors under warranty which are very similar in nature to a two stroke motors. One of the things I have to do for warranty is do a failure analysis to help engineering locate any faults/weakspots in the design and manufacturing process so I would like to understand the 'failure mechanism' here. Personally I suspect the left top reedstop came loose and 'chattered' causing the initial crack to form around that screw hole causing the reeedblock to break away from the portion with the holding bolt going through the bottom cover of the crankcase. Since most of the reedblock was then floating it caused the pin on the block side to egg out. BTW I checked the crankshaft end play and it was OK. Also the motor was never over revved in neutral which I'm not sure is even possible with this motor due to the way the trottle and shift linkage is designed. I enclosed a few pictures of the reed block so you can see the damage yourself
And the locating pin on the back side needs to be aligned. I think I would just get another reed box from a bad powerhead. Other than maybe slight wear from fretting, there is not much to go bad here.