Thermostat opening time

[Porthandbuoy]

In a raw water cooled engine is there a risk of antifreeze damaging the exhaust hose, silencer and/or anti-syphon waterlock?

 

[RichardS]

In a raw water cooled engine is there a risk of antifreeze damaging the exhaust hose, silencer and/or anti-syphon waterlock?

In my experience, antifreeze is pretty innocuous stuff and I've been mixing and matching different types over the last 50 years and never had any problems of any kind.

You will, of course, read different on the interweb.

Richard

 

[DownWest]

I have a 2GM20 on the bench at the moment. If one disconnects the hose from the pump output , the water will drain down to a low level in the block (good luck with undoing the low point drain plug) So does one need to put antifreeze in the system? A small amount of sea water in the bottom of the block is not going to split the block. Oh, the manual says the core plugs in the side are partly there to blow out if the block freezes.

 

[Bilgediver]

When you introduce the cold fresh water the thermostat will immediately close.
If you have block drain clocks or plugs then the sea water can be drained using these then replace or close drains and block can be left empty or filled with antifreeze. There should be an air release hole in the thermostat to allow this to be done using the engine. Takes about two minutes on mine though not a Yanmar. This also fills the exhaust trap with antifreeze. This may be important if leaving the boat ashore.h

 

[ctva]

Sorry you got the snarky response. I didn't need any tea leaves to guess why you wanted to know

My thoughts too. Rather obvious to anyone that has winterised an engine of this type. My 3GM F takes about 30mins in Scottish October temps.

 

[pvb]

When you introduce the cold fresh water the thermostat will immediately close.
If you have block drain clocks or plugs then the sea water can be drained using these then replace or close drains and block can be left empty or filled with antifreeze. There should be an air release hole in the thermostat to allow this to be done using the engine. Takes about two minutes on mine though not a Yanmar. This also fills the exhaust trap with antifreeze. This may be important if leaving the boat ashore.h

The Yanmar manual has instructions for draining the seawater and refilling with antifreeze solution.

 

[richardabeattie]

I think I have now worked out a simple solution. I got an old thermostat and jammed it permanently open. I then put it into the engine. With the thermostat jammed open all the fresh water and then antifreeze mix sucked in by the water pump went throught the engine block rather than the bypass. And yes, I then put a working thermostat back in.

 

[tillergirl]

Bit late this now but in the summer I was suffering overheating on at 1GM. Using an infra-red temperature guage I timed what was happening: At 10.20am cold, the temperature of the block was 20.8 degrees. At 10.25am, the block was 45.2 degrees, at 10.30am was 51.8 degrees, at 10.36am was at 56 degrees. The IGM thermostat starts opening at 42 degrees, fully open at 52 degrees. QED, in an ambient temperature of 20 degrees, the thermostat opened fully in ten minutes.

It might be interesting that the cause of the overheating was salt deposits at the (bl**dy stupid design) tee junction between the block and by-pass. The salt deposit was just inside the block.

QED - a fresh water flush is a good idea (plus AF to end of course).