Hitachi zx 25 overheating...

[Gecko]

Hi Will, I’m a bit late to the party but I have a similar issue with mine at the moment. I suspect the water pump as it’s very squeaky and can’t feed water getting down to the heater matrix. Did you get to tge bottom of your issue? Any help appreciated, thanks Jake

Welcome Jake and good luck solving your overheating problem.
It's always disappointing when someone like @Will zaxis 25 drops in with a question and buggers off without reporting what the problem /solution was. He hasn't been back in 5 years, so unlikely to be a fount of information.

 

[V8Druid]

Hi Will, I’m a bit late to the party but I have a similar issue with mine at the moment. I suspect the water pump as it’s very squeaky and can’t feed water getting down to the heater matrix. Did you get to tge bottom of your issue? Any help appreciated, thanks Jake

pretty reasonable place to start .. I have seen impellers 'let go' when hot and slip on their drive spindle (IIRC Rory had just this issue a year or so back on his truck) ... hotter it gets the less it drives .. can be checked once off by boiling it up and trying to spin the impeller on the drive spindle.
could also be very blocked rad/oil cooler matrices, not allowing air flow, stuck thermostat not opening/jiggle pin stuck?? (causing air locking), or cooling system in need of a damned good flush out/through?