Engine Coolant Overflow Tank is Full

[Vincentc]

The port side engine coolant plastic overflow tank, 671ti, is full to the top, and the stb engine with engines cool is at the "cool level" whent the engines are cool.

The metal reservoir on the port engine appears to be low. I am assuming that the engine water is expanding when hot, flowing into the plastic tank, but not returning when the engine cools.

I would appreciate your advice on whether this is the cause and what is the solution.

My other suspicion is that raw water is leaking into the fresh cooling water. I am running distilled water and pencool 2000 (20 /1 ) and am thinking about using test strips to compare the pencool concentrations in the cooling water between the port and stb engines.
Thanks

 

[SereneWarrior]

Sounds like the coolant overflow system isn't air/water tight. There is likely enough integrity in the system for the expanded/hot coolant to flow from the heat exchanger to the overflow bottle (maybe with a little bit of leakage). However, when the coolant cools/constricts there is air entering the overflow system hose and preventing the coolant from being sucked back into the heat exchanger tank. Check the hose ends from the heat exchanger tank and at the plastic overflow bottle and make sure they are tight. Hope it's that easy/simple for you and nothing more serious.

 

[Vincentc]

Thanks,
I'll try the simple solution.

 

[eze2bme]

Just a thought. Also make sure that the radiator cap is tightened all the way ... even a quarter turn not far enough may affect the overflow not being able to pull coolant back into the system.

 

[Diesel]

Im curious, for those that dont have the overflow tanks, is it common to have coolant expelled from the heat exchanger tank cap until the coolant finds its "happy" level that allows for expansion during heating?

 

[saltshaker]

Im curious, for those that dont have the overflow tanks, is it common to have coolant expelled from the heat exchanger tank cap until the coolant finds its "happy" level that allows for expansion during heating?

If you overfill they will dump the excess coolant out the overflow. I didn't have expansion tanks on my 6V92's. On mine if I filled the heat exchanger to 2" from the top that's where it would stay.