Coolant Change

[Ian_Rob]

I am more or less set up to change my coolant at the weekend. An old posting on the forum mentions that it may be necessary to remove the thermostat when draining/flushing/refilling the system. The service manual for the D1-30 doesn't mention this. Is it necessary?

 

[Ian_Edwards]

I've just changed the coolant on my Yanmar 4JH4E, and it became obvious that you need to warm the engine up to open the thermostat to allow the coolant to circulate through the heat exchanger.

I emptied what I could of the old coolant, via the drain valve, filled with clean fresh water and then ran the engine until it was at operational temperature. I did this three times to flush the system, then filled with 50% water 50% new coolant. I then ran the engine for a while to ensure it was well mixed and then checked the specific gravity to ensure I had frost protection down to at least -25 deg C.

 

[RichardS]

I've just changed the coolant on my Yanmar 4JH4E, and it became obvious that you need to warm the engine up to open the thermostat to allow the coolant to circulate through the heat exchanger.

I emptied what I could of the old coolant, via the drain valve, filled with clean fresh water and then ran the engine until it was at operational temperature. I did this three times to flush the system, then filled with 50% water 50% new coolant. I then ran the engine for a while to ensure it was well mixed and then checked the specific gravity to ensure I had frost protection down to at least -25 deg C.

I agree .... don't open the thermostat housing unless you have other problems.

I follow Ian's procedure but I use concentrated antifreeze so I add the volume of concentrate which equates to 50% of the system volume before topping up to the mark with soft water.

Richard

 

[Ian_Rob]

The D1-30 has 4.1 litres of coolant but I don't know how much is in the calorifier circuit. The idea of flushing with clean water and then adding coolant until it achieves the specific gravity of a 60/40 mix neatly side-steps the issue.

 

[Ian_Rob]

PS Presumably the cheap Halfords Battery Hydrometer I have, will suffice?

 

[VicS]

PS Presumably the cheap Halfords Battery Hydrometer I have, will suffice?

A cheap battery acid hydrometer may not cover the density range with sufficient precision, if at all.

However something like this will do the job easily

 

[Ian_Edwards]

The D1-30 has 4.1 litres of coolant but I don't know how much is in the calorifier circuit. The idea of flushing with clean water and then adding coolant until it achieves the specific gravity of a 60/40 mix neatly side-steps the issue.

I did more or less the same, i.e. added the calculated amount of undiluted coolant and topped up with water, ran the engine and then checked the SG. I did it that way because I was unsure about how much water there is in the calorifier and associated pipe work. I then added more concentrated coolant, because the SG was low.

I have a hydrometer which is calibrated in degrees of frost protection, I've had it for a long time, so can't comment on the Halfords hydrometer. But if the the hydrometer is marked with and SG scale, it should be possible to work out what the SG should be to give the chosen level of frost protections.

 

[Ian_Edwards]

A quick google search give this table from the engineering handbook.

[TABLE="class: large, width: 782"]
[TR]
[TH="colspan: 9"]Specific Gravity- SG -[/TH]
[/TR]
[TR]
[TH="colspan: 2"]Temperature[/TH]
[TH="colspan: 7"]Ethylene Glycol Solution (% by volume)[/TH]
[/TR]
[TR]
[TH](^oF)[/TH]
[TH](^oC)[/TH]
[TH]25[/TH]
[TH]30[/TH]
[TH]40[/TH]
[TH]50[/TH]
[TH]60[/TH]
[TH]65[/TH]
[TH]100[/TH]
[/TR]
[TR]
[TD]-40[/TD]
[TD]-40[/TD]
[TD]¹⁾[/TD]
[TD]¹⁾[/TD]
[TD]¹⁾[/TD]
[TD]¹⁾[/TD]
[TD]1.12[/TD]
[TD]1.13[/TD]
[TD]¹⁾[/TD]
[/TR]
[TR]
[TD]0[/TD]
[TD]-17.8[/TD]
[TD]¹⁾[/TD]
[TD]¹⁾[/TD]
[TD]1.08[/TD]
[TD]1.10[/TD]
[TD]1.11[/TD]
[TD]1.12[/TD]
[TD]1.16[/TD]
[/TR]
[TR]
[TD]40[/TD]
[TD]4.4[/TD]
[TD]1.048[/TD]
[TD]1.057[/TD]
[TD]1.07[/TD]
[TD]1.088[/TD]
[TD]1.1[/TD]
[TD]1.11[/TD]
[TD]1.145[/TD]
[/TR]
[TR]
[TD]80[/TD]
[TD]26.7[/TD]
[TD]1.04[/TD]
[TD]1.048[/TD]
[TD]1.06[/TD]
[TD]1.077[/TD]
[TD]1.09[/TD]
[TD]1.095[/TD]
[TD]1.13[/TD]
[/TR]
[TR]
[TD]120[/TD]
[TD]48.9[/TD]
[TD]1.03[/TD]
[TD]1.038[/TD]
[TD]1.05[/TD]
[TD]1.064[/TD]
[TD]1.077[/TD]
[TD]1.082[/TD]
[TD]1.115[/TD]
[/TR]
[TR]
[TD]160[/TD]
[TD]71.1[/TD]
[TD]1.018[/TD]
[TD]1.025[/TD]
[TD]1.038[/TD]
[TD]1.05[/TD]
[TD]1.062[/TD]
[TD]1.068[/TD]
[TD]1.1[/TD]
[/TR]
[TR]
[TD]200[/TD]
[TD]93.3[/TD]
[TD]1.005[/TD]
[TD]1.013[/TD]
[TD]1.026[/TD]
[TD]1.038[/TD]
[TD]1.049[/TD]
[TD]1.054[/TD]
[TD]1.084[/TD]
[/TR]
[TR]
[TD]240[/TD]
[TD]115.6[/TD]
[TD]²⁾[/TD]
[TD]²⁾[/TD]
[TD]²⁾[/TD]
[TD]²⁾[/TD]
[TD]²⁾[/TD]
[TD]²⁾[/TD]
[TD]1.067[/TD]
[/TR]
[TR]
[TD]280[/TD]
[TD]137.8[/TD]
[TD]²⁾[/TD]
[TD]²⁾[/TD]
[TD]²⁾[/TD]
[TD]²⁾[/TD]
[TD]²⁾[/TD]
[TD]²⁾[/TD]
[TD]1.05[/TD]
[/TR]
[/TABLE]

The table shows that the SG varies considerably with temperature, so when measuring the SG, you need to be careful and that it's corrected for temperature.

 

[VicS]

I did more or less the same, i.e. added the calculated amount of undiluted coolant and topped up with water, ran the engine and then checked the SG. I did it that way because I was unsure about how much water there is in the calorifier and associated pipe work. I then added more concentrated coolant, because the SG was low.

I have a hydrometer which is calibrated in degrees of frost protection, I've had it for a long time, so can't comment on the Halfords hydrometer. But if the the hydrometer is marked with and SG scale, it should be possible to work out what the SG should be to give the chosen level of frost protections.

The info regarding level of protection is printed on the Halfords tester

 

[Ian_Rob]

THANKS everybody. Really helpful!.