During light throttle / slow cruising (not on the plane) the engine temperature is OK but sometimes (not always) the temp soon creeps up to around 210F when on the plane at any speed, though it seems more likely to creep up at lower planing speeds than at fast planing speeds or full throttle. It doesn't always overheat, sometimes the temp gauge stays at 140/150F even at slow planing speeds.
I've only had the chance to watch/check the engine while the boat was being driven on the plane once (when my daughter drove the boat), I could feel slight pulsing on the widest diameter coolant pipe which connects between what would be the top and bottom radiator hose connectors if it were a car / truck. I don't know if the pulsing I could feel is due to pressure changes in the engine internal cooling system due to the thermostat changing how much raw water it allows into the engine (which would be OK), or boiling/steam in the engine cooling channels (bad) or something else.
What could be at fault to cause the overheat and what could be causing the pulsing in the rubber pipe I could feel? I have not tested pressure from the raw water pump but I did disassemble it last year and it seemed in good condition. The engine water pump also seemed to be in good condition when I rebuilt the engine. The same thing occurred when I used the original thermostat and a new replacement thermostat.
This is the engine I rebuilt last year shortly after buying the boat. I'll post a link to the thread I did regards this boat last year but be warned it's a long read, mostly me asking newby questions and not engine related but there is some engine related stuff on the link https://forums.iboats.com/threads/1996-four-winns-sundowner-with-5-0-cobra-engine-and-drive.766501/
Thanks in advance, Simon
I've only had the chance to watch/check the engine while the boat was being driven on the plane once (when my daughter drove the boat), I could feel slight pulsing on the widest diameter coolant pipe which connects between what would be the top and bottom radiator hose connectors if it were a car / truck. I don't know if the pulsing I could feel is due to pressure changes in the engine internal cooling system due to the thermostat changing how much raw water it allows into the engine (which would be OK), or boiling/steam in the engine cooling channels (bad) or something else.
What could be at fault to cause the overheat and what could be causing the pulsing in the rubber pipe I could feel? I have not tested pressure from the raw water pump but I did disassemble it last year and it seemed in good condition. The engine water pump also seemed to be in good condition when I rebuilt the engine. The same thing occurred when I used the original thermostat and a new replacement thermostat.
This is the engine I rebuilt last year shortly after buying the boat. I'll post a link to the thread I did regards this boat last year but be warned it's a long read, mostly me asking newby questions and not engine related but there is some engine related stuff on the link https://forums.iboats.com/threads/1996-four-winns-sundowner-with-5-0-cobra-engine-and-drive.766501/
Thanks in advance, Simon