Typical S197 overheating problem. But... Need advice on work around.

[Chad123]

Hello, all. New here and really never have started a thread anywhere, so please forgive my ignorance in the format of my issue.
I have 07 gt mustang 4.6 3v. Last year I had the typical overheating issue where the fan resistor in the fan shroud was getting hot at the pigtail and scorching the inside connectors. I replaced the pigtail and all was good for about a year. This has recently happened again where I am sitting at a light and radiator starts spewing out fluid. the fan isn't coming on and all relays are good. I have tested them. High and low speed. The current draw from my fan when hooked to straight power is good and approx 22amps. The BEC (fuse relay box) has the power and ground side pins are also scorched this time around.
So the issue isn't the fan drawing too much current as this is a 40amp circuit. My big question is I want a complete work around relay circuit to bypass the wiring and the faulty BEC issue of this design. I have already wired a new 40amp relay and 30 amp circuit breaker. However, my understanding was I wanted to remove the CHT sensor in the head and install a new one and hardwire a sending unit to the new installed relay and all new 10 gauge wiring.
I want the fan to come on with the new sending unit at 195 and off at 185. I have done tons of research and looked over all the forums and I come to the conclusion that if I remove the CHT sensor this will cause irregular voltage to the PCM and cause issues across the entire system.
I want to install a new sending unit to engage the fan and need to know the best place to install a new sending unit since there are no other pre tapped places on the 4.6. Keep in mind I have also ordered a new Water temp gauge and will need another place to install a secondary sending unit for my new gauge cluster. PICs are my actual photos of recent issues.

I am aware of the other options for installing a sending unit in the upper radiator hose and or tap a 1/8 NPT into my water neck. I've heard doing this I will have a intermittent reading as the stat doesn't open and allow coolant threw until temp is at the 180 and opens the stat. However, if my stat opens at 180 when it needs to then my future install of a 185 sending unit on at 195 and off at 185 wouldn't this keep the engine in check due to coolant consistantly circulating and the fan pulling cool air thru when temp goes above the open stat temp?

 

[07 Boss]

So what exactly is your question? If the fan comes on at 195 will it keep the engine cool?

 

[Juice]

I have a suspicion that making those mods will likely fix your fan issue but will create another one for you. Since your PCM controls the fan, and you plan on bypassing all that, you will end up with a check engine light due to removing the CHT sensor from the head.

IMO, the reason those connections melted is due to the age of the car. Connections develop corrosion/resistance over time, that is the reason they melt. I found my connection at the relay pretty much in the same condition as your photo shows. This type of failure is pretty common on high current circuits as a vehicle ages. I would repair all that vs modifying.

If you are dead set on separating the fan controls from the pcm, I would look into a thermostat switch with a probe that you push into the radiator fins or installs into the upper hose or something like that. Leave the sensors in the head so the PCM isn't affected. The PCM uses the CHT sensors for more than just fan control.

 

[DiMora]

If you are dead set on separating the fan controls from the pcm, I would look into a thermostat switch with a probe that you push into the radiator fins or installs into the upper hose or something like that. Leave the sensors in the head so the PCM isn't affected. The PCM uses the CHT sensors for more than just fan control.

I agree with that 100%.

 

[RED09GT]

Yeah, way too complex of a work-around. The system works well until parts reach the end of their service life. Replace it with new parts and call it maintenance.

 

[01yellerCobra]

Can you use the original power wires to run a couple relays? Or even just one relay and have the fan at one speed. Pull the power directly from the battery. Less chance of future meltdowns I would think.

 

[08MustangDude]

AS these fans get older, the motors draw more and more current due
to resistance. That is caused by dirt, or the motor going bad. To truly
repair it, replace the fan with a brand new one, then fix the wiring. It did
not happen till now, much much later right, not when new? Well, there's
a reason, the AGE of the fan motor.

Start up of any motor has a higher current cost, as the fan motor ages and
has drag or resistance, that start-up AMP cost goes up, thus more current to
keep it running. For example, if the motor stalls, the current draw will
spike, and stay high, then melt the wires.

The motor becomes loaded with resistance due to dirt, lack of lubrication,
rust, whatever. As the motor is loaded, the back emf reduces because of
the momentary reduction of the speed, and the motor draws more current
to produce the same amount of the back EMF to produce torque for additional
load on the motor, and also to maintain the motor speed at increased torque.

When nice and new and fresh, under no load condition, the motor runs at its rated
RPM and, because the back EMF induced due to armature current is almost equal to
the applied voltage and motor draws less armature current.

 

[JEWC_Motorsports]

Im with him^. Just because a motor works does not mean its working correctly.

 

[Pentalab]

It get's worse. Typ dc + ac motor's have a typ starting current of triple the running current.
You can measure that with the 'peak' function of a fluke 87 DVM. That start up current typ last only 1 sec..... but is enough to compound any issues. I have an oem 190 deg T stat on my 2010 rad. Starts to open at 190F....and fully open at 200-205 F. Low speed fan comes on at 207F...... shuts off at 197 F. I can watch low speed fan cycle over and over while in idle, in driveway. High speed fan (resistor shorted) kicks in at aprx 213 F.

On my SCT-X3, VMP unlocked all sorts of stuff..and the low speed fan threshold can be set over a wide range. Ditto with high speed threshold. In fact, they overlap.

I had that resistor, fuse, relay all burn up on my 2010 2 yrs ago. Replaced / repaired it all. Oem fan still used..... current draw was same as a new one....so left it in.

 

[brasil]

Sorry for my question here ... but wouldn‘t it be better to install a mechanical Fan ?
I for my self ... I don‘ t thrust those e - fans

 

[Pentalab]

Sorry for my question here ... but wouldn‘t it be better to install a mechanical Fan ?
I for my self ... I don‘ t thrust those e - fans

RPM of mech fan increases / decreases with eng rpm. That's exactly what u don't want. E fans have been in use since aprx early 80's. With the car moving at say 25-30 mph, u don't need a fan.
Mech fans gobble up a lot of hp.

 

[brasil]

What you say is correct so far . But I have no problems to give up some horses - when I can stay relaxed . Because the good old mechanical fan does not brake . E - Stuff is always full of gremlins

 

[1950StangJump$]

So . . . roll down windows in lieu of AC then? Cable driven speedo, carburetor, and no ABS?

Just askin'

 

[Norm Peterson]

So . . . roll down windows in lieu of AC then? Cable driven speedo, carburetor, and no ABS?

Just askin'

OP's problem was very specifically electrical in nature. The fan itself could be overdesigned to the point where it was as reliable as an anvil, and the connector would still be what caused the cooling system to be compromised.

Technological changes still have to be done up right - physically, mechanically, electrically, thermally, etc. - if you actually want to call them improvements and not simply exercises in technology for its own sake. OP's connector and Pentalab's resistor, fuse, and relay didn't make the cut, at least not long term.

Listing those other things is a specious argument that has a hint of techno-snobbishness about it.


Norm

 

[1950StangJump$]

Come on, now, Norm. The idea that a mechanical fan is the answer is ludicrous. And, my "specious" way of expressing that was meant to be humorous.

 

[RED09GT]

I think all of us who owned a fox body can attest that a mechanical fan can cause just as many problems as an electric and be equally difficult to diagnose. I went through a few fan clutches and they always seemed to die at the most inopportune time. At least with an electric, you can tell when it is not working-not so much with a failed fan clutch. I
even tried going to a non-clutch fan at one point and that was a huge mistake, sub 10's for fuel economy and it made my car into a complete slug, not to mention the fan noise was something awful. I later switched to a mark VIII electric and a flex a lite variable speed controller and lived happily ever after.
I suppose you could try and fit a water pump and clutch fan from a 2002-2010 explorer or truck, build your own shroud and kill off 20 or so hp and a couple MPG as well.

 

[Norm Peterson]

Come on, now, Norm. The idea that a mechanical fan is the answer is ludicrous.

brasil may have had more than his share of electrical problems. Maybe not so silly to him.

And, my "specious" way of expressing that was meant to be humorous.

Maybe so. But people trot out the exact same argument - down to some of the exact same examples - to beat down on those who are not as enthusiastic about the newer technologies as they are. Kind of hard to tell the difference between joking and "you're so not with it".


Norm

 

[Terry]

There are over 46,000 S197's out there and I'm sure if electric fans were the problem it wouldn't just be Mustangs that would be going back to mechanical fans, so would every car maker! And since that's not happening, my bet is that this is isolated to this car or any make or model of car that has this problem. I could be wrong, but I doubt it's the fan (assuming no accident damage) since that would manifest itself as melted wiring as well as possible melted connectors. But if it's just the connector that's melted then the problem IMHO probably lies with corrosion or a loose fitting at the connector. The blade connectors when fitting properly have a surface area and thickness that allows the specified current to be passed efficiently. However, if corrosion or an ill fitting connector reduces the surface area and thickness then the same current passes through a smaller amount of metal which then acts like a filament and lights up like a light bulb!! The OP seems dead set on replacing the system fan but if he cant get his head around trying a relatively simple connector replacement, then he is going to be in a world of hurt trying to make a silk purse out of a sow's ear with a mechanical fan! IMHO!

 

[07 Boss]

What you say is correct so far . But I have no problems to give up some horses - when I can stay relaxed . Because the good old mechanical fan does not brake . E - Stuff is always full of gremlins

So let me get this straight. You want to attach a fan to your crank or pump pulley or somewhere and run a separate belt, build a shroud and hope it works, vs fixing an electrical malfunction? That sound effin brilliant. Can't wait for the write up.

 

[Pentalab]

The emergency diesel gen set at the telco I worked at, the fan ate 59 hp off of the crank per the power engineer. And that was a small setup, inline 6 cyl, no turbo, 115 kw. A 240 vac barrel fan, would do 15K cfm, and draw just a few amps.