Better MPG after replacing thermostat ....
Thread Starter
MBWorld Fanatic!
Joined: Mar 2008
Posts: 1,232
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From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
Better MPG after replacing thermostat ....
I had finally got round to replacing the thermostat a couple of weeks ago as the car has been taking ages to heat up inside during the winter, its an easy job and cheap , I also flushed the cooling system and replaced with new MB antifreeze.
Good news is that the car heats in a fraction of the time now and at below freezing outside the car is warm inside in less then 5 mins and that the engine temperature reaches normal temperature much faster then before in around 10 mins, previously it would the needle would stay low for 20+mins.
Also however i've noticed that the MPG has improved slightly by around 5mpg, my thoughts are that because the thermostat now opens correctly and quickly,it allows the coolant to flow, whereas before it remained within the engine block taking longer to heat as there was more volume of coolant. As the thremostat now opens the coolant flows and the engine gets warmer quicker thus making the car reach its operating temp faster and better MPG.
Good news is that the car heats in a fraction of the time now and at below freezing outside the car is warm inside in less then 5 mins and that the engine temperature reaches normal temperature much faster then before in around 10 mins, previously it would the needle would stay low for 20+mins.
Also however i've noticed that the MPG has improved slightly by around 5mpg, my thoughts are that because the thermostat now opens correctly and quickly,it allows the coolant to flow, whereas before it remained within the engine block taking longer to heat as there was more volume of coolant. As the thremostat now opens the coolant flows and the engine gets warmer quicker thus making the car reach its operating temp faster and better MPG.
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Joined: Apr 2005
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From: SCV SoCal
2002 CLK430
You may have that backwards. The new thermostat closes completely, allowing the coolant to stay in the block until the engine reaches operating temperature. This is opposed to the old thermostat, which stayed partially open, allowing coolant to flow through the entire cooling system. The engine took longer to reach operating temperature with the old thermostat because the engine had to heat more coolant.
Some Japanese vehicles have thermostats that fail this same way. It kills fuel economy and makes them fail smog because the ECU is always in enriched mode.
Some Japanese vehicles have thermostats that fail this same way. It kills fuel economy and makes them fail smog because the ECU is always in enriched mode.
Thread Starter
MBWorld Fanatic!
Joined: Mar 2008
Posts: 1,232
Likes: 168
From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
You may have that backwards. The new thermostat closes completely, allowing the coolant to stay in the block until the engine reaches operating temperature. This is opposed to the old thermostat, which stayed partially open, allowing coolant to flow through the entire cooling system. The engine took longer to reach operating temperature with the old thermostat because the engine had to heat more coolant.
Some Japanese vehicles have thermostats that fail this same way. It kills fuel economy and makes them fail smog because the ECU is always in enriched mode.
Some Japanese vehicles have thermostats that fail this same way. It kills fuel economy and makes them fail smog because the ECU is always in enriched mode.
