The Function and Malfunction of the Diesel Thermostat

kaiser · 20th January 2012, 22:43

A thinking hat is always required. Even, and perhaps especially so, when you least expect it.

I haven't got a clue about the construction of the Diesel engine, but I can see the picture of the thermostat insert. It is similar to the one used in the V6.

Now the V6 I know very well!

So the way the V6 works is like this.
When engine is cold. Thermostat is closed. Small spring loaded valve is off base, and allows water to flow from pump back into the engine. The water circulates around the inside of the engine, and into the heater, only. The radiator is not used.

As the water heats up, the top disk starts moving down, opening the flow to the radiator, and the small disk starts to move down in unison, starting to close the flow into the block.

At fully open top disk, the thermostat is allowing all the water to flow from the pump directly into the radiator, having, with the small disk, blocked any passage of hot water back in the engine.

What the pump experiences is that it can circulate water. Initially just around the engine, which will assist with a uniform even heating up, and eventually switching to fully circulating into the radiator.

Now, I am going to assume here, and I know I shouldn't do this, but it would be rather strange if the operation of this thermostat is not exactly alike.

If I knew the construction of the fitting area, it would be easy to ascertain.

20th January 2012, 22:43	#9
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	A thinking hat is always required. Even, and perhaps especially so, when you least expect it. I haven't got a clue about the construction of the Diesel engine, but I can see the picture of the thermostat insert. It is similar to the one used in the V6. Now the V6 I know very well! So the way the V6 works is like this. When engine is cold. Thermostat is closed. Small spring loaded valve is off base, and allows water to flow from pump back into the engine. The water circulates around the inside of the engine, and into the heater, only. The radiator is not used. As the water heats up, the top disk starts moving down, opening the flow to the radiator, and the small disk starts to move down in unison, starting to close the flow into the block. At fully open top disk, the thermostat is allowing all the water to flow from the pump directly into the radiator, having, with the small disk, blocked any passage of hot water back in the engine. What the pump experiences is that it can circulate water. Initially just around the engine, which will assist with a uniform even heating up, and eventually switching to fully circulating into the radiator. Now, I am going to assume here, and I know I shouldn't do this, but it would be rather strange if the operation of this thermostat is not exactly alike. If I knew the construction of the fitting area, it would be easy to ascertain.