520xi WILL NOT CRANK

[TDF5G 2,051]

My brother has 1998 520xi 2 cylinder Kohler.  He mowed with it Saturday for about 30 min.  He had to stop do something and went back about an hour later and it would not crank.

 

He calls me and says the battery was showing 12-13v output.  The relays click when turning the switch to start.  All connections clean and tight (he claimed).  He tried tapping starter.  Still nothing.   

 

I finally got a chance to stop by his place after work yesterday to see if I could help.  I have no experience with X series tractors at all.    All my  are B and C series. 

 

So I get there yesterday evening and see the same thing he is telling me.  Tried to jump solenoid and nothing but relay clicking.  Multi-meter showed 12 volts to solenoid. I was stumped.   Don't know what the wiring setup is on these and what gremlins they may have, with oil switches fuel pump relays, etc.   Checked interlock switch on brake and seat, ok.  The mower blade switch has about 8 wires going to it, didn't mess with it.

 

So I play police detective and start giving my brother the third degree with questions.  He said when he went back to start it on Saturday (when it quit) he heard kind of a clunk sound and would not crank and that was it.  So I'm thinking starter problem. I ask him about the battery, (he had trickle charger on it now).  He said it was 6 years old.    What the heck.  I never had one last over 3 years!  He keeps it so clean that the battery looked new to me!

 

So I said let's try to jump start it.  He brings battery charger with 75 AMP start boost.  We tried to crank at 2 AMP first, nothing.  Then tried 15 AMP, nothing. So I switched it to 75 AMP boost and when he turned the key there was a loud pop like a firecracker and something flew out the front of the tractor.  (Grille and side panels had been removed before this.)  He jumped off and found one battery cap out in the driveway which had blown off.  

  

So I removed the battery, the positive cable was only just snug.  That was probably what caused the gas from battery to ignite.   Then we tried to jump start it with the 75 AMP again without a battery in it.  This time I could hear the starter trying to engage, but just wouldn't do it.  So we pulled the starter and connected it to 12 volts and it will spin but the bendix gear didn't jump out.  I couldn't remember exactly  how to test the solenoid, which I think activates the drive bendix gear, been too long for me.  It has the solenoid mounted on the starter like a small block Chevy.  I did notice shiny spots on the flywheel where the bendix gear wasn't engaging and shiny spots on the bendix gear.  He turned the engine by hand and I saw more shiny marks around just about the entire flywheel.  Makes me think the bendix gear drive isn't working properly maybe?

 

I had to get home so later last night I cruised youtube for solenoid checking videos and sent it to my brother and told him to check this and buy a new battery first and try that before spending $ on a starter, which easy to remove/install. 

 

Sorry for the long post.  My question for you xi series guys:  What else should we check?  And how many AMPs should spin it over to start it? 

Edited June 14, 2016 by TDF5G

[russellmc301 600]

try unplugging everythind and repluging it in 1 at a time. on rusty there is 1 wire i do it to and it works everytime.

[TDF5G 2,051]

Talked to my brother last night.  He installed new battery and she fired right up.  All is well.   I passed along the info about unplugging and reconnecting.

Thank you, Todd