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Hello All,

I am in need of a little professional help. I have a 1993 350l. The other day It was running great. I took it for a ride around the house and pulled back into the garage. This is when it all happened. It was idling fine for a few min when all of a sudden it back fired (sounded like a shot gun going off) I could not get it started. I left it for several days and tried to start again with no luck. The only way I could get it to even pop was to spray starting fluid in the carb. I figured it was a carb issue so I rebuilt it again with no luck. Tore top of engine down to discover a hair line crack in the bottom of the piston skirt. Rebuilt top end with a wiseco piston. Had it bored and matched to the new piston .5mm over. I have great compression 125psi. However the engine will still not start same simptoms. Is it possible that when the engine back fired it took out a crank seal? What else could be the issue. I have good spark, fuel, and compression.

Thank you
 

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First off, welcome to the board!
 

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Here are some symptoms I have seen before after a machine back fires. You could have bent or streched the rod. Check to make sure you did not sheer off the flywheel key and if you did you will want to inspect the flywheel for possible damage. I have never heard of it taking out a crank seal but anything is possible.
 

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Discussion Starter #4
Thank you for the reply.


I Checked the flywheel key today while pulling the crank seal, it was ok, I am waiting for a clutch puller tomorrow so I can pull the other side and replace. When I rotate the clutch back and forth I can hear a hissing sound, it sounds like it is coming from the seal behind the clutch. As for the rod, when I had the top end rebuilt all checked out fine.
 

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Discussion Starter #5
Ok, The wheeler is running like a top. Once I removed the clutch, I found the crank seal blown out. I bought a bottom end seal and gasket set and replaced all. Now the bad news, while doing so I broke the temp sensor on the head. Does anyone know where I can get one of these and is this the sensor that turns on the fan for the radiator? I ran the engine for about 5 minutes but the fan never turned on so I shut it off. I do not want to burn the engine up after all the work I have done. What is the temp the engine should run at when the fan turns on?
 

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i believe what you broke was the sensor that makes the idiot light come on. the switch that tells the fan when to turn on ,should be on the top part of the radiator. if you want you can use a lil test wire and unhook the sensor and connect the two wires temporary together together to make sure you fan does work .it need not be running to do this ,just have key in on position. they do have to get pretty warm for the fan come on 210-216 degrees .keep an eye on the coolant level when you first start an run it ......sometimes it takes a while to get all the air out.
 

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Discussion Starter #7
Thanks to all, my machine is up and running. I have had it out several times in the last dew days. Cant wait to burn through the tank of double oil and its broke in. So far the thing runs flawlessly.
 
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