JD425 Problem

NCmau

Member
While mowing, my JD 425, 94 edition emitted an ugly noise and stopped. Tried to start it but the engine was frozen. Manually rotated the drive shaft and I was able to crank it but no engine start. The flywheel engaged okay but there was zero compression. While it was turning, the front PTO was also turning. Then the engine locked up again.
I guess I am looking to perform some kind of surgery. My first wild guess would be the timing gear, which for this early model is plastic. But then a connecting rod and maybe piston(s) could be very possible candidates. What would be a reasonable approach, take the timing cover off or take the whole engine off and go from there? If possible, I would like to minimize my work.

P.S. As an additional note, when I checked compression I noticed the inner electrode of one spark plug was loose and was touching the plug point. Obviously there was no spark out of the plug. I do not know if the engine running on one cylinder could have caused the mishap.
 
not to steel your question but is it better to re power with new motor or rebuild ??new motors are still available
 
Well, when I try to take shortcuts, I usually end up with more time in it. Since it sounds like you have determined the problem is internal and you don't know how much you will have to do, I think you probably should pull the engine and put it on a bench. It will be much more convenient.
 
I would bet that the cam gear came loose from the cam shaft. QUIT trying to crank it you will tear something else up. The cam and gaskets will be around $250
 
(quoted from post at 07:00:50 10/19/14) I would bet that the cam gear came loose from the cam shaft. QUIT trying to crank it you will tear something else up. The cam and gaskets will be around $250

I got the engine on the bench and opened the crankcase cover about 3/4”. The cam gear is metal and it is all in one piece, however I could see remnants of connecting rod(s) at the bottom of the case. This is not good news. I was hoping the cam gear was plastic and to be shattered, unfortunately it is not. So it looks like it is a bigger job for my pay grade that I had anticipated.
Question, I got the crankcase cover out about 3/4”, but I am having hard time to pull it out any further. I tried to use an oak wedge and tap it on both sides but it not moving. I am trying to be extra careful not to cause any unwanted damage. All bolts are definitely out.
I could use some suggestions.
 

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