Coolant Drain 2015 R31 (D4-300)

[JeffreyAC77]

Can anyone direct me to the proper drains to change out my coolant? TIA.

 

[abastos]

You can find detailed instructions in the Service and Maintenance, D4-D6 PDF. Download it from https://www.volvopenta.com/en-us/your-engine/manuals-and-handbooks/ using the engine serial number.

Pages 58 to 60. Preview below:

cooling-system.png

• abastos
• Jan 26, 2026

 

[JeffreyAC77]

I have found those diagrams - thanks. Are they the only two locations to drain the coolant on the D4-300 (2015). - pictures 1 & 3?

 

[DavidO]

I have found those diagrams - thanks. Are they the only two locations to drain the coolant on the D4-300 (2015). - pictures 1 & 3?

Note of caution. Those drain cocks are plastic and not available. So, be very careful and don't over tighten.

 

[JeffreyAC77]

Note of caution. Those drain cocks are plastic and not available. So, be very careful and don't over tighten.

Thanks for the warning. Are there only 2 drain locations to do the whole system on a D4?

 

[DavidO]

Sorry, not versed on the D4, just learned the hard way about the drain cock.

 

[sgeary]

Yes, those are the only two drain cocks on a 2025 D4-300.

 

[JeffreyAC77]

Thanks for your confirmation. I have read about needing drain the hot water tank as well - is that true or am i wrong about this?

 

[sgeary]

I believe you are referring to the engine coolant circuit that goes through both the water heater and the helm controlled cabin heater. I believe you will find owners who recommend draining that circuit when doing a coolant change and other owners who do not. There are two valves on the front of the engine that open or close this circuit. When I did my coolant change, I chose to close those valves and only drain the engine block coolant as I was concerned with introducing air into the hot water heater/cabin heater circuit. This meant I was not replacing all the coolant, but since I do this about every three years, I was not concerned with mixing old coolant. Your 2015 D4 probably has Volvo yellow antifreeze in it. I believe that for the last year or two, you can only purchase Volvo orange antifreeze. But the orange antifreeze is advertised as compatible with the older yellow antifreeze. In my previous comment, I mistakenly said 2025, rather than 2015 D4. My boat is also a 2015.

 

[zekeandboone]

I believe you are referring to the engine coolant circuit that goes through both the water heater and the helm controlled cabin heater. I believe you will find owners who recommend draining that circuit when doing a coolant change and other owners who do not. There are two valves on the front of the engine that open or close this circuit. When I did my coolant change, I chose to close those valves and only drain the engine block coolant as I was concerned with introducing air into the hot water heater/cabin heater circuit. This meant I was not replacing all the coolant, but since I do this about every three years, I was not concerned with mixing old coolant. Your 2015 D4 probably has Volvo yellow antifreeze in it. I believe that for the last year or two, you can only purchase Volvo orange antifreeze. But the orange antifreeze is advertised

Hey Steve!
About how much is extracted?

 

[JeffreyAC77]

I believe you are referring to the engine coolant circuit that goes through both the water heater and the helm controlled cabin heater. I believe you will find owners who recommend draining that circuit when doing a coolant change and other owners who do not. There are two valves on the front of the engine that open or close this circuit. When I did my coolant change, I chose to close those valves and only drain the engine block coolant as I was concerned with introducing air into the hot water heater/cabin heater circuit. This meant I was not replacing all the coolant, but since I do this about every three years, I was not concerned with mixing old coolant. Your 2015 D4 probably has Volvo yellow antifreeze in it. I believe that for the last year or two, you can only purchase Volvo orange antifreeze. But the orange antifreeze is advertised as compatible with the older yellow antifreeze. In my previous comment, I mistakenly said 2025, rather than 2015 D4. My boat is also a 2015.

Thanks for your answer - it is much appreciated.