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300AI cooling issues


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2004 granite 300 AI/Allison combo having overheating a issue. When tagging the excavator (82k gross), water temp climbs to the edge of the red when accelerating from a dead stop to 45, but starts falling fairly soon once throttle backs down (maintaining 40-45). At lower weights, never gets close to red. Radiator rodded out a year or so ago, 50/50 antifreeze changeout yearly, fan clutch appears to be pulling good, Allison verified no trans issues(trans temp stays mid range)...what else should i be looking at? Possibly the cooling package is marginal(seems like i read something on BMT about the 300 hp motors having a “economy” cooling system available for non A/C trucks with a smaller water pump???)

This truck was a non-A/C mixer truck up north originally, maybe a marginal radiator with A/C and our ambient temps?

any ideas?  
 

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The AC and AI engines have 2 thermostats , if one to stick it can cause overheating. Also , if the engine does not have a coolant filter or the coolant SCA levels are out of range , it can cause corrosion in the cooling system. Pull the water pump off and look into the aluminum housing that’s bolted to the block . It should be smooth. I’ve pulled several water pumps off and had severely pitted housings that caused overheating. 

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For the ASET engine family I only remember there being 2 different water pumps. One of the AI engines and one for the AC engines. The pulley diameter was the only difference. It was very easy to put the wrong one on and saw it happen quite a few times. The belt might be a little tight or loose but they will easily bolt up and cause cooling issues 

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