schmickle

So my car battery has died twice in the last 24 hours. Both times when the jumpers were hooked up, the fans turned on up front.

But I need to add something else - I checked my coolant and found it extremely low. I topped it off...with nearly a whole jug of premixed coolant. There is no leak thou - it was in storage for a long while and just needed to be filled up.

So, did the fans keep running because there was no coolant fluid to aide the cooling down? Or is the thermostat shot?

Thanks

gilwong

You should not be losing coolant at all--if in storage or if operating properly in use. Especially not a whole jug of coolant. Something is wrong, needs to be checked out.

schmickle

Yes, I know I shouldn't be losing coolant. But it was a very slow loss that I just didn't pay good enough attention to.

What I need to know now is if the thermostat is gone or if the lack of coolant could have lead the fans to run the battery dead.

The car is going to the shop this weekend. I just need to get my beater ready to take over for a week...

roadrunner

Would your cooling fan thermo switch be going bad? That's usually the case when the fans stay on for too long. Even with low coolant, the fan should not stay on for more than 5 minutes after the engine is shut down.

Tom M'Guinn

If your engine is cold and the radiator fans come on as soon as you apply power to the battery, then that is wrong and is probably killing your battery. The fans should only come on when the coolant is warm. If fans come on when the motor is cold, this is caused by a bad temp sensor or relay or other electrical issue. It is not caused by low coolant or a bad thermostat. The low coolant is also a problem, as mentioned, and potentially more troublesome.

Beamz

i had a similar problem and went to check my thermostat but found i didnt even have one! without the thermo the water in the rad doesnt get a chance to slow down and cool down so the fans just keep working over time. If yours is stuck open this could be the case. Also the fan rely on the RAd is worth changing and also the relay in the fuse box ( cheap and easy). I did both and stopped this problem straight away. Now my fans act like they should and come on slow to keep the temp down and usually run for a minute after shut down. My main fan only comes on once in a blue moon now OR when the air-con is operating.
Also my fans used to come on as soon as i turned the cars igniton on so i knew the sensor must be shot.
Regards
Craig

roadrunner

Beamz,

Somewhat OT, but the thermostat doesn't slow the water down so it can spend more time in the radiator. This is a major fallacy. If it did this, then it would spend even more time in the cooling jacket and pick up enough heat to flash into vapor, which you definitely don't want.

Tom M'Guinn

There is a bypass port in the throat of the water pump that allows coolant to recirculate inside the pump before the t-stat opens. When you run without a t-stat, the bypass stays open all the time and the pump may not circulate as much coolant as it would with a t-stat installed. So, in theory, the coolant can run hotter without the t-stat. Having said that, I removed my t-stat when I moved to Miami and my car never ran cooler. I could drive for hours in 90 degree weather and the temp would barely get to the first hash mark. With the t-stat in place and working as intended, the temps would average between the first and second hash marks.