hotwiring of radiator fan cause battery drain?

Question

I drive a 1992 standard transmission Geo Storm, and lately the radiator fan hasn't been coming on and the car has been overheating. A mechanic hotwired the fan to come on whenever the car is on, bypassing the thermostat. A couple of days later, the battery was completely dead for no apparent reason. I talked to someone about it and they said that hotwiring the fan like that could have created a continual circuit that drained the battery even while the car was off. He also mentioned that there were bubbles in the radiator, which indicates that there is junk in the bottom which might be impeding the thermostat, causing the fan to not come on, the whole problem in the first place.
The owner of the car told me that there is a leak where the hose connects to the head. She put a few containers of 'GUNK' stop leak in the radiator over the last couple years. Could this be what is impeding the thermostat?

Let me know what you think of this problem, please. I do not want the battery to discharge again. For now, I am disconnecting the battery when the car is not running.

To summarize:
1: Will a direct hotwiring of the fan to the battery drain the battery even when the car is not on?
2: Will crud in the radiator impede the thermostat and stop the fan from coming on when it should?
3: Could the 'Gunk' that the owner used to plug a leak be the cause of this crud, impeding the thermostat?

Answer 1

Gunk on whole can clog your radiator, damage the thermostat and cause the temp sensor to malfunction.



Bubbles in the radiator mean that you either have an air pocked in the cooling system or you might have a damaged head gasket which both can cause overheating.



As long as the hot wiring is done to an ignition controlled component, the fan will only come on when the ignition is in the on position meaning that it will be on when the engine is running. so it should not drain the battery given that it is well wired with no possibilities of it grounding out and causing shorts and damaging the alternator the causing the alternator to discharge the battery.



a faulty temp sensor would have been your problem to begin with. its not sending the proper reading telling the fan to come on.

Answer 2

1. Direct hotwiring of the fan to the battery *WILL* drain the battery when the car is not on, verify that the fan is NOT hotwired to the battery directly and is instead wired through the ignition by checking under the hood after you have turned the car off. You can hear and see the fan turning in most cases. It should be evident when the car is running and evident that it is not running when the car is not.



2. Crud in the radiator will, in general impede your cooling system and it can clog or otherwise damage a thermostat. This, however, will generally cause the engine to run hotter, which should cause the fan to run more, not fail to run. I think your problem is more likely the coolant temperature sensor (there may be two, one for the gauge and one for the fan, so you'll need to double check this) rather than the thermostat. If you replace this, and un-hotwire the fan, you should at least have fixed the electrical issue. I would recommend, however, REPLACING any leaking component (radiator, etc.) and using a cooling system flush product to clean the Gunk crud out of the system, because:



3. Yes. That crap is horrible. It may stop a radiator leak, but it also will block passages in the radiator and especially in the heater core, which on many vehicles is a real pain to replace, so I would never use radiator stop leak of any kind. It can screw up the thermostat too, and if that's the case, no manner of fan hotwiring will keep your engine from overheating.



Next steps: replace the radiator, if it was leaking and "fixed" with stop leak, it's a bad radiator, sorry. replace the thermostat, probably ditto. I'd replace any hoses associated with the cooling and heater system as people don't replace these nearly often enough, usually wait until they leak, or blow completely, and then you have real problems, so I'd do this now while it's easy. Then I'd replace the faulty temperature sensor - your parts store should be able to direct you to the right part here. THEN, I'd have your mechanic friend un-hotwire the fan. Everything *should* be okay now, except that there is still gunk floating around in places that are difficult to impossible to get to, such as in the cylinder head, engine block and heater core. Not much you can do about that, and I wouldn't recommend replacing anything unless it's completely unworkable. Again, flush and fill, try to clean it up as best as you can.



Good luck!

Answer 3

Your GUNK stop leak has plugged up the radiator and now you have a motor that over heats. Chances are the heater core is also plugged up with that crap. Never use a stop leak type product in the cooling system. It will cause more damage. Find the leak and replace what ever is leaking. If the radiator fan turns off with the key off it is not drawing the battery down.

Bubbles in the radiator means you have an air pocket and need to purge the air from the system. Run the motor for 15 minutes with the heater set on the hottest setting, the radiator cap and/or the reservoir pressure cap off, and the front of the car raised higher than the rear. Park on a hill if you can't jack it up. That will help get all the air out. The radiator fan sensor may have been surrounded by air which will keep from turning the radiator fan on.

Answer 4

my sisters ford escort has a hot wired fan,,,fine for the last 4 years

crud can ruin the temp sensor,,,clean it if no joy replace it

gunk or other radiator seal is sure way to finish off a dieing radiator,,,replace it