resunoiz

Hi, here's a maybe stupid question, almost a curiosity.

My car has a CNG fuel system and it results, in summer days, in engine running at slightly highe temperature than normal ones (102/104 deegrees).
So I was wondering if disconnecting the thermostat in long trip with a lot of traffic may result in a "benefit", leaving it always open.
Disconnecting the electrical connector the thermostat remains always open (resulting in a better refrigeration) or always closed?

Thnaks to the one that will answer my weird question

audiophool

The electrical part of the thermostat is a heater designed to open it more quickly/farther during periods of high load operation. If you disconnect it, your car will throw a code. And I don't think it would help your problem at any rate, if anything make it worse.

resunoiz

thanks, was infact a curiosity.

do you know if there are thermostat that opens at lower temps?

audiophool

No, I don't. I would suggest if your CNG conversion makes the engine run hotter that it could be running too lean. You say it runs warmer, but does it actually overheat? If not, I don't really see a problem.

BimmerFan52

Sounds like you are trying to lower the coolant temperature once the engine reaches its normal operating temperature.

Purchasing a thermostat that opens sooner will not achieve this. It will cause your engine to take longer to get to 90C (which is where your present thermostat probably opens) leading to poor gas mileage during the extended heat up (a cool engine does not burn fuel efficiently).

Whether the thermostat opens at 50C, 70C or 90C, if the engine's normal full operating temperature is 102C, any of these thermostats will already be open at 90C and then the coolant will continue to increase in temperature (while the thermostat is fully open) until it stabilizes at 102C (the balance between the heat produced by the engine and the ability of the coolant system components including the radiator and electric fan to remove heat energy from the coolant).

102C is not unusually hot, especially for the E60 sealed coolant system. Because it is designed to be operated sealed, as the increased pressure of the coolant passes 100C (boiling) the coolant system's internal pressure increases. As ambient pressure increases the boiling point of the coolant also increases so it continues to flow as a liquid and not turn to steam. The reverse is also true of lower ambient pressures - a pot of boiling water will boil at about 157F at the top of Mt Everest, instead of 212F at sea level.

To operate at a lower coolant temperature you would have to make significant changes like adding more radiator capacity. I wouldn't worry about 102C.

E60Japanese

I wouldnt be dissconnecting it but rather be figuring out why it is running hot.


I agree with Bimmerfan52 that its not running so hot but dissconnecting the thermostat will throw map codes and cause other problems.


Did you check if you have any error codes at all?
Any map codes?


Don't try and bypass the problem
find out what the problem is and fix it

resunoiz

thanks a lot.
as said, is effectively almost a curiosity.
the car runs warmer as the CNG is not liquid, so it's "normal" to run at higher temps almost 5-10 degrees higher in almost cars.
so in summer the temp tends to became high resulting in a continue vent operation and a major risk of pressure/gasket issues.