questions about used KENWORTH T700

My friend recently got a 2011 KENWORTH T700 with 450hp cummins engine thru the prop 1B program and the truck had a message on the comp saying it had water in the fuel and code 13 when he first test drove it he chose to go with the truck because the dealer was supposed to fix the problem along with cracked bumper brackets and a few cosmetic issues.so the dealer fixed everything but the water in fuel problem because they "FORGOT" so he took it back to the dealer and the dealer is debating on wether they or the warranty has to pay for the fix up.my friends friend mentioned that it could be a problem with the fuel injectors or something with the head leaking water into the fuel lines or a new filter.
and we were wondering that in worst case scenario the problem isn't fixed by the dealer and isn't covered by the warranty how much could a problem like this cost and what could the problem be?

p.s is it possible to adapt the hydraulic clutch system of the 680 to the 700 and if it is how much would it cost?(rough guess)

 

Bad news is there's no time to backout of the deal because PROP 1B program says he has to have his new truck on the road by the 15th of next month and all this prop 1B stuff has taken a process of at least 2 1/2 months so they could give my friend the $50K grant.so he's pretty much stuck with this truck because of the program and because of the DEF filter requirements for all trucks nowadays.good thing is he has a 91 freightliner FLD still running pretty well for a truck that's over 20yrs old with 1.4mil miles since now he can have a truck without a filter since he has one with the DEF the only small drawback is he can't enter the rails or the Long beach ports.not too bad since the company he works for has trucks that enter and take out trailers for him and other trucks