I suggest you established what the problem is. From all your posts there appears to be two problems. (1) Overheating (as defined in your title). What is the evidence that it is overheating?. (2) coolant is pumped out of the filler when the cap is off: what happens if the engine is run with the cap on?This is what the owner sent me from his mechanic.im very confused. Am I right the mechanic perhaps doesn't know what he is at? That was in response to my asked Ng if then elbow could be the issue and if it was replaced yet.
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Ok guys let’s just for a minute assume the engines actually fine , nothing wrong .Never was anything.Been chasing shadows all along .Hi Folks
I have been offered a boat for sale due to overheating issues with one of the engines.
I'm not familiar with the exact engine model, or if this is an issues with this particular engine?
The owner is selling it as he has simply given up.
He has spent a fortune, and it still overheats. He has had the following work done
Oil & filter service
Raw water pump rebuilt
Turbo replaced Engine
Coolant pump rebuilt
Engine coolant hoses replaced
Heat exchangers stopped port - stbd
Cylinder head removed, pressure tested and skimmed
Injector sleeves replaced
Compressions checked
Coolant checked for exhaust gases.
HAs anyone any ideas where to go from that?
Its a really beautiful boat, and exactly what we would be looking for. If we knew we could resolve the problem.
aftermarket at around £160.00 not that sure that the genuine VP items @ £280.00 are that much better quality. ?They are a consumable item for sure! Not that expensive and easy job

Why in your eyes is every overheat post on here caused by excessive EGT , the photo shows the boat not under load , as I’ve said it will blow water without the cap on . The 41 is a very simple engine and I’d bet the fault is a very simple one .Ok guys let’s just for a minute assume the engines actually fine , nothing wrong .Never was anything.Been chasing shadows all along .
The overheat is from excessive EGT s and overloading caused by excessive friction in the stern gear apparatus ( inc the g box ) .So we need to check the P bracket cut less bearing , gen alignment, etc and somehow the g box friction.
Thinking tiny engines relatively to the boat .You know barely enough torque to knock the skin off cold custard .
Not true .Why in your eyes is every overheat post on here caused by excessive EGT , the photo shows the boat not under load , as I’ve said it will blow water without the cap on . The 41 is a very simple engine and I’d bet the fault is a very simple one .