Overheat when flushing, but not running. 2005 280 da, twin 4.3 with alphas

[stuartfl]

Starboard engine fine, used same rectangular muffs on both stern drives, both engines ran great for 8 hours at 4000 RPGs over weekend, port engine overheated when flushing, lowered back in water and took boat out at 4000 RPGs and both engines fine, back on lift, starboard, no issue, port overheated while flushing again, any thoughts?? Thanks

 

[Bucit]

Not enough water pressure from the city water? Maybe you have an impellar that needs replaced on the port outdrive. If they are weak they won't pull enough water from the muffs.