Water cooling system

While I was working on my engine cooling system (Universal 5411 / M15) I found a device in line that I think is a pressure relief valve. The device is screwed into a tee in the cooling water line. My question is; Is this a pressure relief valve? Is it on all diesels? Should it be routinely replaced, if so with what? This device is not shown on any diagrams that I have seen. I could be an anti siphon device but again I have not seen anything like it. John B CAL 227 #650

John, If it's in the hose between the engine and exhaust elbow, I will guess that it is an anti-siphon valve. Michael From: John Boyce <je… [at] gmail.com> To: Ca… [at] yahoogroups.com Sent: Friday, August 16, 2013 3:33 PM Subject: [Cal_Boats] Water cooling system While I was working on my engine cooling system (Universal 5411 / M15) I found a device in line that I think is a pressure relief valve. The device is screwed into a tee in the cooling water line. My question is; Is this a pressure relief valve? Is it on all diesels? Should it be routinely replaced, if so with what? This device is not shown on any diagrams that I have seen. I could be an anti siphon device but again I have not seen anything like it. John B CAL 227 #650

Is it the thermostat? Is the T located to enable a bypass of the coolant system until the engine warms up? If it is a thermostat, don't replace it, but keep a spare for when it eventually fails. From: John Boyce <je… [at] gmail.com> To: Ca… [at] yahoogroups.com Sent: Friday, August 16, 2013 3:33 PM Subject: [Cal_Boats] Water cooling system While I was working on my engine cooling system (Universal 5411 / M15) I found a device in line that I think is a pressure relief valve. The device is screwed into a tee in the cooling water line. My question is; Is this a pressure relief valve? Is it on all diesels? Should it be routinely replaced, if so with what? This device is not shown on any diagrams that I have seen. I could be an anti siphon device but again I have not seen anything like it. John B CAL 227 #650