First of all, I'm a Yanmar guy, so don't know the ins and outs of Atomic 4's. This all started with a lack of water at the exhaust, correct? Now we have established raw water flow to the mixing elbo. If the amount coming out the exhaust is not normal, then perhaps some clogging inside the mixing elbo. This is common with Yanmar. If the raw water can't flow, it can't cool the engine.
If the amount coming out the exhaust is normal, then maybe a fresh water cooling system problem. You stated that the heat exchanger was cool, but maybe this is the raw water temperature and not the engine temperature? How hot did the engine get? Did it warm up faster than normal? This could be the fresh water pump or the thermostat, or some other fresh water circulation problem. Richard Arper rtar...@wavecable.com -----Original Message----- From: David Knecht via CnC-List [mailto:cnc-list@cnc-list.com] Sent: Friday, June 6, 2025 1:49 PM To: Stus-List Cc: David Knecht Subject: Stus-List Re: Water pump mystery Some progress to report. One step forward. One step back. I checked the strainer last night and all good. Reassembled hoses and found no water coming out of pump inlet hose at pump height but dropping it to bilge height got good flow. I could hear lots of air being pushed out and then just water. Hooked everything up and pulled hose where raw water enters mixing elbow. Started engine and got a gallon in there time it took me to get from key switch to engine compartment. Looked good. Started engine and seemed i was getting some water out back and pump housing stayed cool. But engine temp started to rise in a few minutes so i shut it down. Hoses and heat exchanger seemed cool. I know the antifreeze tanks are full. Why is antifreeze not cooling engine now? I am thinking about taking the mixing elbow off since it is the only thing i haven’t looked at. If that were partially blocked what would the engine do? Dave Sent from my iPhone Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated. Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated.
