It's not an alternator problem. If it were, your battery would simply go dead. If you insist on keeping the electric fan setup I would rewire them. There are a number of wiring kits available to control the fans. You can use an engine mounted temperature switch, or one that mounts in the radiator. You can also include a manual override that allows you to switch the fan on next time the engine gets hot. I have wired up a couple of them and prefer the engine mounted temperature sensor. But FWIW I still think you should ditch the electric fans and go with the factory setup.

 

too expensive too go back to original and these fans worked since they been on
this is a new thing
I'm just going to change out the wires and alternator n put a manual switch on
where they will still work like their supposed to but if they fail to come on i have the option of turning them on ..it needed an alternator anyways and the battery I just replaced cause it did die on me and the volt meters aren't where I'd like them to be .
it's reading 12.5 to 12.9 driving .
right now its going off the thermostat sensor I think ??
is that not right?
thank you
I'll update everyone

 

it might be 60 for both
I could barely read the number
But they are the ones that came with it
This all came complete and just put on last year .
something is causing fans to shut off
They need to pull air even when driving especially on these hot days lately

 

Finally, pictures! Please post more. Do you have a temp switch in the circuit?

That circuit breaker is likely the reason that your fans are turning off. Can you also confirm your timing, and actual temperatures?

When it overheats, have you confirmed the temperature with an IR gun yet? Everything will be hot to the touch under the hood, most everything will be 150 degrees F or so, or more. But actual temps are useful for debugging. Shoot at the upper, and lower, radiator hoses, and tell us what you get.

Do your fans ever turn off in the driveway? They should be cycling on and off if they were wired correctly. And they should be OFF on the highway. No need for them. Your shroud has flaps to let air bypass the fans, and the front spoiler is, from what I see, mounted such that it directs additional air into the radiator through the slots under the nose (please correct me if my assumption is incorrect).

So, if your fans need to be running to keep your engine cool, there is something else going on. Possibly timing.

The 60 Amp Bosch-style relays are correct. One for each fan. They need to be rated such for the contactors to survive repeated cycles. Each fan is probably 15 Amps when running, but the inrush current at startup is much higher.

That block next to the relays is likely a self-resetting circuit breaker. That is what is overheating and disconnecting. I don't know what that small red wire goes to, but if that the downstream side, whatever it is feeding is also turning off when the circuit breaker trips.

This thread has a similar issue, with a similar circuit breaker setup, but also inferior fans.

https://www.corvetteforum.com/forums...n-problem.html

 

This is correct. That is a "short stop" It needs to be rated well above the 60 amps you are pulling. It trips due to heat. Combined with under hood heat it will trip early.

On hot days the fans will run continuously, mine do. With A/C on they should run continuously. Nothing wrong with those fans. I have had the same ones for 10 years+ now. They provide adequate cooling.

 

I also use these same $120 spal clone fans on a 3row champion rad. My fans only really run in stop and go traffic or while sitting idling. Ive had no issues in the 3 years ive been using them and my coolant temps never go over 190. I am powering each fan from the starter lug which has a second 4awg painless wiring power wire from the alt to the starter. I use 2 10awg wires from the starter to the fan relays with a 30amp resetable swing arm type breaker on each fan. I do have a derale dual fan controller setup to control my 2 external 30amp relays that control the fans. Often only one of my two fans ever kicks on because the controller doesnt activate the second fan unless the temps climb an additional 15 degrees.

It is not good idea to power the fans directly from the alternator stud.

If your alternator voltage is really dropping to 12.5-12.9 your alternator is struggling it seems and the lower the voltage the higher the current draw which doesnt help with wires, connection points and breakers heating up. I have a volt meter in my car and the cheap chrome 105amp alternator (I rebuilt with better quality components) does not typically drop below 13.1v and thats with my stereo system and amps going as well.

 

How many posts have we seen in here on guys trying to convert/fix/adjust electric fan setups and throwing more money at the problem? And the funniest part, I think, there is no benefit over the clutch fan except a loss of a few HP while cruising around at 5000+ rpms!

 

I ran a #2 gauge DLO with copper crimps right from the starter to a fuse block on the wheel well. It goes to a 50A relay and has a 30A fuse. I'm only running a single fan in the factory shroud, with about a 1" from the water pump pulley.
I can idle in heavy traffic and it won't move in temperature. The headers on the other hand heat the cabin up so much, it's almost like torture.

 

Plenty of real world and dyno testing shows 7-14hp real world losses with clutch fans and up to 40hp with direct drive fans. This topic will be one of those things were people will often only see or believe the data they want and do what they want. Its like discussing points vs electronic ignition Ive used both. Ive also had both a new working clutch fan and my electric fans to base my experience off of in the same car. For me the electric fans are far superior in function.

Plenty of electric fans systems here that have not been installed properly to begin with. Theres also just as many car overheating threads with mechanical fans in use. Theres lots of reasons these cars can overheat or run too hot. The fans are not always the cause or solution.

 

HP loss is at high rpms. Most of us don't drive around at 5000+ rpms. So the loss at 2500 rpm is irrelevant because it might be 1 hp. Remember, it only takes about 50 hp to cruise at 60 mph/2500 rpm. At 120 mph/5500 rpm 200 hp, yes, the hp loss would be about 10 hp or so from results I've seen.

 

I don't know why people who have not made the swap and experienced the difference continue to pontificate on what it MIGHT be like.

 

We're here helping folks get their electric fans to work because lots of times a PO put them in wrong. So getting them to work IS the cheaper option, on top of being better. A shroud, clutch, and 7-blade fan is a few $hundred, and is an inferior solution for anyone who wants a strut brace, wants working AC, or wants to stick their face and hands near a running engine.

Unfortunately, sometimes this means the OP might need a new alternator and some wiring to make right. But it's worth it.

I'm also surprised by folks who have electric fans that run when the wheels are turning. That has not been my experience, or @augiedoggy's, it seems. Here's a plot of a recent run, including up and over a mountain pass. At NO point in this plot did my fans come on. The highway pass was at highway speeds, the rest at country road speeds. You can see the temps I recorded. The second photo shows the mess of thermocouple wires, the bypass loop from before I blocked the heater core circuit, my dual-Spal electric fans, Stant rad cap (highly recommended for debugging), and the (single) 195 on 185 off thermo-switch mounted in the intake.

 

With my 3000 stall torque converter my fans do run more than they would otherwise. Without that they would rarely ever run short of high temp days.

 

You are right as far as my wiring. The small red wire y I u didn't know where it went goes to the electric choke
not sure why he ran it there .
But definitely not timing .
If it was it would be running rough or pooping or backfire n maybe run how but no boil over .
n timing is good I know of for sure.
All my Temps are correct thsts for sure
it starts boiling over at exactly 250 degrees on my temp gauge .
I'm not sure if that red wire to choke is a problem or not?
I'm not much on electrical.
But I just installed my alternaror n rannnew wire n connector!
now my volt guage is reading where it should be around 14.1v at idle .it was 12.7
but now my car is idling real high after I installed alternator???
it's idling at over 2000 rpm 900 in gear
it use to run 1000 at idle n 700 in gear !!??
not sure what caused that!!?
please help!!
I am getting rid of the circuit breaker it's hooked up now n put a junction block there in place of it ?!
but it definitely needed an alternator!
Just don't know why it's idling high now?
Also there is a green wire I seen laying there not hooked up I noticed when hooking alternator up?
and a bolt that came on new alternator where it says ground to block?
but the old one didn't have one on it
I assume the ground is on the other bolt on alternator.
I'm sending pics with this?
If anyone has any advice!

 

It runs fine as long as I'm not stopped or running for a while with stop n go
the fans do need to be on n it runs great
Once they go off they don't kick back on ?
I'm still thinking that circuit breaker n replacing with junction block?
n maybe the wire from breaker to choke where fans are hooked up might be an issue..idk??

 

A few thoughts:

If you are using the aftermarket digital gauge to tell you the coolant temp, you could be way off. Buy an IR temp gun, and use it. Even knowing the temperature change across the radiator will help.

If you haven't timed the car yourself, you don't know what the timing is. It could run "fine", but still be 10 degrees or more retarded at cruise, which will contribute to your overheating. Following the numbers in the shop manual is not best practice for your modified engine (or even a stock one).

I'd replace that circuit breaker with two fuses, 30 A each, each feeding one relay/fan. As others have stated, the best place to get this power is from the starter. I use MBRF fuses, FWIW, with a fuse block in the engine compartment for individual circuits.

If your choke coil is fed from that circuit, find a separate circuit. Feeding IGN switched power to the choke coil is good. (Not for the fan relays, though) Can you post pictures of the carb from all sides with the air cleaner assembly removed? Stock 80s had a choke relay on a dedicated 20 Amp fuse.

 

Thats still a concern. the fans should only be running sparatically while driving.

If you timing was off just a bit the engine might run great but too hot. Have you timed it to 34-36 degrees total advance at 3000rpm with the vacuum line disconnected and plugged? If not how have you verified your timing is correct?

You mentioned a new alternator? What is the amp output of the alternator? You need a minimum of 60amps and if you have a sound system or AC running you likely need more than that. This could be why your voltage dips down to 12v

 

I just installed a 150 amp alternator now my volts are reading 14.2 at idle
it definitely needed an alternator.
But since I installed alternator now my idle is around 2100 rpm and 1100 in gear
​​​​it use to be 1000 at idle and 700 in gear ??
I installed it the same way i took it off ??
I don't know why that is !!??
Also noticed a green wire laying next to alternator I don't know where it goes ??
If anyone could help i would appreciate it?!
also I'm getting rid of that circuit breaker and installing a Bus bar and running the electric choke to a different source today

 

I'm trusting my mechanic that he timed it correctly
and in all my years I've never seen or heard of timing causing it to overheat so hot it boils over
maybe run a lil hot but no boil over n run that good ?!
n thats my problem they aren't aren't sparatically or at all when driving. They should come on when on hot days especially at a stop or in traffic they are not!
but work fine when idling at home for hours n shut off n on when suppose to
but no sooner I drive it they stop working!
I'm thinking that circuit breaker where relays are plugged into along with choke wire is my problem.
idk

 

That may be so....but I have......seen manifolds and headers glow red......which is like 1100 degrees......especially under a load.......and this heat transfers into the cooling system......
Check the timing and rule it out.......most GM HEI's are 15 initial/36 total......

Jebby