6420 starter issue

[Aussie Ken]

I have a 6420 here in Australia with IVT and about 600 hours on the tach -- the customer keeps having issues with the starting - if it sits overnight or even a couple of hours, the starter labours and the engine turns over slowly. It will start most times -sometimes he needs to boost it.
Once it is running, the starter turns it over better and starts every time
The starter had been replaced already by the customer.
The Battery is 1100CA -900 CCA and it tests good
The customer has ran a second positive cable to the starter from the battery -so there are two from the battery and the third cable to the boost post on the cab.
I cleaned all connections on battery, ground post on engine block, and starter bolt.
I tried the battery load tester on the battery - approx. 900CA
I connected the tester to the starter bolt and the end plate on the starter for ground - approx. 700CA
We are dropping 200 CA somewhere -the cables all look good
Charging system appears good, with 14.4 volts at battery when running
Testing voltage at the starter with my multimeter, on some starts, the voltage doesn't dip below 10.3 volts
Other starts the voltage drops to 9.0 Volts
I do not know the state of the surface of the flywheel housing where the starter bolts -possibly rusty and not making a good ground?
I have suggested running a second ground wire from the battery to the starter -I would prefer that the wire be under the bolt securing the starter to the flywheel housing, but its almost impossible to access that bolt --
Possible a battery drain, and a disconnect would help?
Possible residual pressure in the IVT or hydraulic system causing a hard crank issue?
Thanks in advance

 

[Bob]

I recently dealt with a 6420 that did all sorts of tricks like that (NOT an IVT, tho).

Issue was main hydraulic pump not de-stroking sometimes.

Took a look inside pump, stroke control piston bore was badly worn, and there's no sealing rings, just a (formerly) precision fit between the piston and the bore.

Replaced the pump with a DEERE reman (from Turkey) and all is well.

There's several other things in that 9nightmare) pressure and flow compensated hydraulic system that could probably stick and cause issues as well.

 

[Tech 7]

Hey Ken I thought there was a DTAC solution that dealt with a problem like this. Memory is a little fuzzy.