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Smoke from Engine and empty reservoir

Hello,
Sunday afternoon from at about the halfway point of a weekly drive 45 minutes from home on the freeway I noticed my thermostat needle jumping up and down. I immediately turned of the a/c and turned on the heater. Turning on the heater helped as the thermostat stayed at lower temperatures. I never reached the red zone until I was on stop and go traffic on the surface street near my home.
The next morning I checked the fluids in my car. All fine except the reservoir fluid was low. i added coolant to the line and went on my way. About four miles down the road my thermostat again began to jump around and stay in the red zone I again turned the heater on but there was no heat and smoke came from my hood. I immediately pulled over safely on the side of a surface street and waited for my engine to cool. This time the reservoir was completely empty and the coolant in my radiator was low. I towed my car home and waited for the engine to cool. I refilled the reservoir and the radiator with fluid. No leaks. I ran the engine for over 15 minutes. No leaks. However, I noticed the fan never came on.

Could this be a leaky reservoir or a broken fan motor? I don’t know how else to troubleshoot.

How many miles on the car? Check the fuse’s and relays for the fans. Check the oil for coolant. Also I would replace the thermostat. Get a fail-safe type if you can. Has the water pump and timing belt been replaced? If that don’t work. You may have a bad head gasket.

I think you’ve diagnosed the problem already. Something is probably wrong w/he radiator fan. The radiator fan should be spinning like a banshee if the temp display on the dash is reading more than 3/4 full scale. If it isn’t spinning, something is wrong.

You can do a little experiment if you like. With the engine cold, open the hood, and start it up in your driveway, and let it just sit there and idle. At first the radiator fan shouldn’t come on. But in 5-10 minutes the temp display on the dashboard should reach 2/3 to 3/4 full scale, and the radiator fan should start spinning. If it doesn’t, something is wrong, and not addressing the problem immediately could damage the engine.

It could be the fan itself, the wiring to the fan (not unusual if the battery is leaking, as the battery is typically right above the fan connector). But the most likely cause is a faulty coolant temp switch. This switch comes on when the coolant temp reaches a certain temp. If it sticks in the off position – which isn’t uncommon in older cars – the radiator fan simply will not come on. Ask your mechanic to check that first. (I’ve done this myself on my Corolla, by unscrewing the switch from the engine and putting it in a pot of hot water, hooking it to a VOM, with a thermometer in the water to see if it clicks “on” at the specified temp.)

BTW, this incident may have damaged something. The radiator may have sprung a leak. Or a hose may now be leaking. Carefully monitor the coolant level, & look for coolant leaking under the car. You may need a new radiator. Or you may need a new head gasket. Pray to the car gods it is the radiator, not the head gasket. A replacement radiator is quite inexpensive. Faulty head gasket? Not so much.

You were very smart to turn on the heater full blast when you noticed the overheating. You may have saved yourself big bucks by doing so.

Best of luck.

I have well over 250K on the car and the timing belt is fine. I replaced the radiator about two year ago due to a crack which was a few hundred dollars with parts and labor.
I would really like a cheap fix like a leaky hose but I don’t think that is the issue since nothing leaked when I tested the car on idle in my garage. I was also hoping that I just overlooked something and my worse nightmare, a blown gasket, isn’t the problem but I believe my suspicions have been confirmed a damaged fan or a bigger problem.
Turning on the heater full blast was a tip I learned from my father, or cousin I cant remember.
My mechanic is looking at my car tomorrow. I trust that he will find the issue and I will report back what the findings are.
Thank you @oldbodyman & @GeorgeSanJose you have been a great help!!!

Do the fans come on when you turn on the AC. Tuning on the AC should force the fans on.

Hello @gsragtop the fan didn’t come on when my mechanic turned on the A/C.

The car is fixed for now. We changed out the radiator cap and the thermostat and that seems to have fixed the problem. the thermostat was stuck closed and the radiator cap had a part fall off from under the cap. I am also changing the relay for the fan as well.
I will recommend this community to my friends if they have any car trouble and I love CLICK and CLACK!

If the fans are nit coming on with the AC, AND the AC actually works. Then you are not out of the woods yet, they must work to keep your car cool at slow speeds.