electric fan issues

[pass1over]

not s197 related, but figured I could bounce a problem off any sympathetic ear.

Have efi swapped 331 in my 66 car. Everything's been running great until few months ago. Noticed my battery voltage was dipping down into the low 12s (or lower) at times and figured out it was whenever my electric fan turned on, also caused my alternator belt to squeal like crazy, and my rpm's to drop down to around 5-600. Unplug fan and idle bumps up and alternator output goes back up to 13.8-ish

I figured it was an alternator going bad as the 3g unit I had was pulled from a junkyard car that I got for free. Replaced alternator and car is doing the same thing. Battery voltage drops whenever fan turns on and alternator screams.

Fan is wired through a relay, relay has direct power from battery. Power wire from battery to relay is like 10 inches long and 10 gauge I think.

Other issues that might be occurring? Bad ground? Weak battery? Fan going bad?

 

[crjackson]

Your fan may be failing, and drawing too much current. Since it was fine a few months ago, and assuming you’ve made no other changes, it’s something to checkout.

 

[pass1over]

I don't think my meter would measure that high of an amp load. I was going to swap a known good battery into the car, drive it and see what happens. I can rule out the battery that way as least.

 

[Dino Dino Bambino]

Your fan may be failing, and drawing too much current. Since it was fine a few months ago, and assuming you’ve made no other changes, it’s something to checkout.

This.
If the fan motor bearings are worn out and are generating too much friction (and heat), that'll increase the amp draw until the fan motor eventually burns out.

 

[86GT351]

My beet would be the fan starting to fail. I would suggest replacing and also replace the relay. As the fan goes bad it kicks resistance back to the relay.

 

[pass1over]

After I realized it was not the alternator, the fan became my next suspect.

The battery is of unknown age. Last time I went for a drive, I forgot to secure it down and it fell over in the trunk and some of the water leaked out. I can't refill it as it's sealed. This is why I suspect it as well.

I'll do my battery test to rule out out before I buy another fan. I'll replace the relay too as they're cheap.

How'd you S.Florida people fare the storm?

 

[Bullit0969]

not s197 related, but figured I could bounce a problem off any sympathetic ear.

Have efi swapped 331 in my 66 car. Everything's been running great until few months ago. Noticed my battery voltage was dipping down into the low 12s (or lower) at times and figured out it was whenever my electric fan turned on, also caused my alternator belt to squeal like crazy, and my rpm's to drop down to around 5-600. Unplug fan and idle bumps up and alternator output goes back up to 13.8-ish

I figured it was an alternator going bad as the 3g unit I had was pulled from a junkyard car that I got for free. Replaced alternator and car is doing the same thing. Battery voltage drops whenever fan turns on and alternator screams.

Fan is wired through a relay, relay has direct power from battery. Power wire from battery to relay is like 10 inches long and 10 gauge I think.

Other issues that might be occurring? Bad ground? Weak battery? Fan going bad?

 

[Bullit0969]

If your belt is squealing your alternator is slipping with reduced output.

 

[pass1over]

If your belt is squealing your alternator is slipping with reduced output.

You are correct, I can see the actual alternator output on my ECU software and it does indeed reduce in output. I'm trying to figure out why.

 

[DieHarder]

Sounds like the fan bearings are going; good idea to replace the radiator fan. Was having issues with mine where it wouldn't turn on. After troubleshooting everything else it was the only thing left. Once replaced everything works as it should. When I got the old fan out it would still spin on the bench but the bearings felt like they were binding; especially compared to the new one. Not all that surprising after 15 years.

New replacement fan:
https://www.cjponyparts.com/fan-ass...m_term=1101201852513&utm_content=All Products

You might also check your belt tensioner if the belt continues to squeal.

 

[pass1over]

Sounds like the fan bearings are going; good idea to replace the radiator fan. Was having issues with mine where it wouldn't turn on. After troubleshooting everything else it was the only thing left. Once replaced everything works as it should. When I got the old fan out it would still spin on the bench but the bearings felt like they were binding; especially compared to the new one. Not all that surprising after 15 years.

New replacement fan:
https://www.cjponyparts.com/fan-assembly-electric-mustang-2005-2014/p/FAN56/?year=2007&msclkid=2082a55fd326195b830fc619c4052c00&utm_source=bing&utm_medium=cpc&utm_campaign=New Bing Shopping Ads&utm_term=1101201852513&utm_content=All Products

You might also check your belt tensioner if the belt continues to squeal.

This fan problem is on my '66 mustang with a pushrod 5.0 swap. The tensioner in this setup is my alternator, lol. But you are almost correct on the age. I think I did that swap/setup almost 20 years ago now. I haven't tried to free spin the fan to see how the bearing feels. Nor have I gotten around to testing the battery like I want to.

40 acre horse farm, and 4 other vehicles .... always something else getting in the way.

 

[DieHarder]

Ah, sorry, wasn't paying attention. Simpler system. Understand on the farm. Never enough time. Good luck.

 

[Jim O]

I understand wanting to replace the battery but that would not cause the belt to squeal, I concur on the fan motor