[sluggo]

I have a Kohler model 7.3e( 2006)   for some reason, it starts and runs good for maybe all day, but then the next day will only run for 5 hrs and then the next day maybe 2 hrs.
This past week, it ran good for 2 hrs, but we shut it down, and a few hrs later fired it back up no problem, but after an hr it shut itself down again.
We have trouble shot the usual suspects, impeller good, pumps water good, we back flushed the cooling system and didnt really get anything out, the tech checked most everything he could think up.  The housing on the water pump side stays cool.

So any ideas on what caused the shut down?  
Could it be wired to the CO detectors and they shut it down?  (but they are not going off yet they work)

Could be an 'elbow' in the cooling system that Kohler supposedly  recalled? 

any ideas are appreciated!