It's Happened Twice Now....

[bmeaggie]

You can see the two relays here. 25 = high ; 28 = low

https://www.autogenius.info/ford-mustang-2005-2009-fuse-box-diagram/

 

[07 Boss]

So to make sure... have you overheated the car, opened the hood without shutting off the engine, and made sure you can still activate the fan by turning on the AC?

If “yes” to that for certain... There are TWO fan relays... a high speed and a low speed (1 & 2). I think the high speed = ac activated. Maybe your low speed relay is bad?

No the car didn't overheat but when I got to my destination I popped the hood to verify the fan was still going. Car was at normal operating temp which is a hair below most as I have an electric pump. when I cut the ac the fan turns off. Now, I'm not sure where I have the low and high fans to kick on and off, but I would think the low speed fan would be on at normal operating temp. I just don't have a whole lot of time at the moment but I will. Good point that the low speed relay might be out, but wouldn't the high kick on a a certain temp and prevent the overheating?

 

[bl817]

I also see that you still have the AC system in place. are the fins on the condenser bent and restricting air flow? I know on my DD (rsx) that when I have the front bumper off again (to install new headlights) I will comb the fins on the condenser as the ones exposed thru the bumper are pretty beat up. I know my GT could use the same treatment when I have the bumper off again. I have a set of fin combs I got off the zon for less than 10 bucks. might not be the issue but a better flowing condenser would help engine cooling and AC performance. also, how are the coolant tank caps? if they are old they might not let the system come up to pressure and keep things cool, just another thought. good luck

 

[bmeaggie]

No the car didn't overheat but when I got to my destination I popped the hood to verify the fan was still going. Car was at normal operating temp which is a hair below most as I have an electric pump. when I cut the ac the fan turns off. Now, I'm not sure where I have the low and high fans to kick on and off, but I would think the low speed fan would be on at normal operating temp. I just don't have a whole lot of time at the moment but I will. Good point that the low speed relay might be out, but wouldn't the high kick on a a certain temp and prevent the overheating?

It’s hard to prove cause without inducing the failure mode. You need to catch it in the act so to speak.

You can easily rule out the relay by swapping the two of them, turning on your AC, and making sure the fan comes on regardless which one is in pos 25 and which is in pos 28.

If those are good, I’d bet money your fan motor is starting to go out.

Next time you see temp gauge go past 1/2 and trending upwards, pull over, leave car running, pop the hood, verify fan does NOT run with and without AC on, pop off the fuse box cover and carefully feel those two relays. If they are hot as hell (like too hot to touch), you have what I had, and swapping fan out was the only thing that fixed mine. You gotta do all that kind of quickly because what happens next is a big steamy mess.

 

[saleen836]

Good point about the 2 relays.

A friend of mine here in the UK just had his GT500 overheat, diagnoses was the low speed fan relay stopped working which in turn prevented the hgh speed relay from working

 

[07 Boss]

Ok, I got her to overheat following the scenario the last time it happened. Started the car at work with the ac on, verified the fan was running, drove about 13 miles in the heat of the day (Vegas, 95% freeway), stopped at the mini mart/gas station. Before turning the car off I heard the fan running. Couple minutes later jumped in the car and started her up. I did not verify fan operation at this time, should have. Two blocks and two stoplights later she started to overheat as I pulled in my driveway. Unfortunately she started spewing steam and water and I was unable to pop the safety on the hood to verify if the fan was running.

Few hours later I went out and refilled the cooling system with about just under a gallon. Started the car, ac on and the fan was purring away. I let it get up to temp. Well as high as she will go with the fan running and idling. Funny thing with that electric pump flowing and the fan on high my car will only get to about 1/3 of the gauge. I have to give it gas to get it to creep towards the center or 1/2 on the gauge. Anyways I got her to just below midway on the gauge. Went and verified the fan was still running. Turned off the ac and the fan went down to low speed and continued to run. Pulled the low speed relay and the fan stopped. Plugged the relay back in and the fan did not come back on. Went and turned the ac back on and still no fan. Turned her off and went to bed.

This morning I checked the fluid level, started the car with ac on and no fan. Drove her all the way to work (two lights before freeway and then didn't stop until I parked at work). The temp stayed steady at it's normal spot just below 1/2. When I parked I popped the hood and the fan still wasn't running. At that point the temp started to rise and I shut her down. And here we are.

At this point I'm thinking the fan motor is the culprit. Maybe it is something with the relays getting too hot. Everything is way hot to the touch under the hood in the summer time. Even the cover to the fuse box feels pretty soft and flimsy from the heat and hot to the touch. I think I'm just going to fix up my track set up (something is wrong with it, put a fuse in it and no power to the fan switch) and just turn the fan on manually until I can get this car into my garage and get to the crux of this matter. That is part of the problem which is turning this into such a saga. It's pretty damn hot here. I'm having issues with my RacecaR build and it's up in the air and going nowhere for a while. Working in the driveway with this heat is considered a health hazard.

I will report back after I get home. I should be good getting her home in the 115* heat with no fan as long as I don't have to stop. After maybe two lights leaving work I don't have to stop until I hit my driveway, all right hand turns but one and that one is an uncontrolled intersection.

 

[07 Boss]

I also see that you still have the AC system in place. are the fins on the condenser bent and restricting air flow? I know on my DD (rsx) that when I have the front bumper off again (to install new headlights) I will comb the fins on the condenser as the ones exposed thru the bumper are pretty beat up. I know my GT could use the same treatment when I have the bumper off again. I have a set of fin combs I got off the zon for less than 10 bucks. might not be the issue but a better flowing condenser would help engine cooling and AC performance. also, how are the coolant tank caps? if they are old they might not let the system come up to pressure and keep things cool, just another thought. good luck

From what is visible everything looks in good order. last time I had the bumper off I had my boy pick all the debris out of the radiator, condenser and heat exchanger for the inter-cooler.

 

[07 Boss]

It’s hard to prove cause without inducing the failure mode. You need to catch it in the act so to speak.

You can easily rule out the relay by swapping the two of them, turning on your AC, and making sure the fan comes on regardless which one is in pos 25 and which is in pos 28.

If those are good, I’d bet money your fan motor is starting to go out.

Next time you see temp gauge go past 1/2 and trending upwards, pull over, leave car running, pop the hood, verify fan does NOT run with and without AC on, pop off the fuse box cover and carefully feel those two relays. If they are hot as hell (like too hot to touch), you have what I had, and swapping fan out was the only thing that fixed mine. You gotta do all that kind of quickly because what happens next is a big steamy mess.

I tried to get under the hood but I was too late to get the safety latch undone without burning my hand.

 

[07 Boss]

If I do go get a fan motor do I just get an oem replacement? I've seen GT500 fans mentioned a couple of times. How are they different? Do they bolt right up? I stock fan has been good to me up till now as far as capacity.

 

[Juice]

No clue about the GT500 fan being any different. All I can say is the V6 fan keeps the coyote cool just fine. So I vote OEM. I have a feeling they are the same damn thing. lol Any CFM numbers on any of them?

 

[07 Boss]

No clue about the GT500 fan being any different. All I can say is the V6 fan keeps the coyote cool just fine. So I vote OEM. I have a feeling they are the same damn thing. lol Any CFM numbers on any of them?

Here is one that says its an upgraded Ford Performance one (Ford Performance M-8C607-MSVT) that says 3286 cfm. Don't know what the stock one flows. This says 7 blade, not sure how many the stocker has.

 

[bl817]

Stock GT fan has 6 blades and the GT500 has 7. not sure what year they changed the design so I would go with a 13'-14 GT500 fan. I think I looked on rockauto a while back and verified they were actually different. not sure about the motor itself if it is different than the stock GT one. 14' GT500 fan assembly DR3Z-8C607-C, 05' GT and up DR3Z-8C607-D

 

[07 Boss]

Stock GT fan has 6 blades and the GT500 has 7. not sure what year they changed the design so I would go with a 13'-14 GT500 fan. I think I looked on rockauto a while back and verified they were actually different. not sure about the motor itself if it is different than the stock GT one. 14' GT500 fan assembly DR3Z-8C607-C, 05' GT and up DR3Z-8C607-D

Well I think I'm just going to get a stocker from my local Ford dealer. I know it's going to be twice as expensive but I kinda gotta get her fixed up quickly as she is my daily and I currently don't have a back up ride that's on all four wheels. I can get a cheap Dorman replacement but I think I'm going oem.

 

[bmeaggie]

Well I think I'm just going to get a stocker from my local Ford dealer. I know it's going to be twice as expensive but I kinda gotta get her fixed up quickly as she is my daily and I currently don't have a back up ride that's on all four wheels. I can get a cheap Dorman replacement but I think I'm going oem.

Another stocker is fine, but the general consensus in the tuning community is the Ford ‘13-‘14 GT500 fan is the best plug n play offered for s197 mustangs. They mount exactly the same on the stock radiator. You can do either and be good... just don’t get some aftermarket one that only has 1 speed.

 

[bambam 06]

Boss, i had the same problem as you a few years ago, we have the same cars. I got this radiator M-8C607-MSVT for about $200.00 from a Ford dealer out west, can't remember the name, no more overheating.3,286 cfm, 7 blades. Just remove old one, install new one,one hour.

 

[bambam 06]

Boss, i had the same problem as you a few years ago, we have the same cars. I got this radiator M-8C607-MSVT for about $200.00 from a Ford dealer out west, can't remember the name, no more overheating.3,286 cfm, 7 blades. Just remove old one, install new one,one hour.

I just remembered Levittown Ford.

 

[bmeaggie]

Boss, i had the same problem as you a few years ago, we have the same cars. I got this radiator M-8C607-MSVT for about $200.00 from a Ford dealer out west, can't remember the name, no more overheating.3,286 cfm, 7 blades. Just remove old one, install new one,one hour.

Yep... that’s the ‘13-‘14 GT500 fan. Really is the best one for our cars from what I understand.

Picked up my last one at Summit Racing.
https://www.summitracing.com/parts/...MI3YXYiMSe6wIVh7zACh3MjggMEAYYAiABEgKrafD_BwE

 

[07 Boss]

Boss, i had the same problem as you a few years ago, we have the same cars. I got this radiator M-8C607-MSVT for about $200.00 from a Ford dealer out west, can't remember the name, no more overheating.3,286 cfm, 7 blades. Just remove old one, install new one,one hour.

I was looking at that one but they didn’t have one in stock. I’ve never had an issue with cooling when the fan was running so capacity was never an issue. I actually have a hard time getting my car fully up to temp sometimes. It was just a matter of it actually turning on. I picked up a stock one but not sure I’m going to get it in tonight. But that’s ok I got the wife’s little turbo sportage tomorrow for my half day at work. I may be running out of light to swap it now.

 

[crjackson]

Hope you got this sorted out, but I upgraded my fan to the GT500 7 blade model and it’s way better on my car. Even the AC blows colder. I still have my stock radiator and fan in case of an emergency, but I’ll never go back to my stock Boss 302 radiator and fan.

 

[GlassTop09]

Just to put it out here.........................

Outside of the advent of the 7-blade cooling fan on the 13-14 GT500 cooling fan to improve low speed cooling vs the 6-blade cooling fan on the OEM stock unit, there is another improvement on the 13-14 GT500 unit that is seeming to be overlooked........

Look at the picture of this fan thru the link that bmeaggie provided in post #37 & you should notice the set of trap doors.....2 on each side of the fan shroud in the lower section.......... These are not present on the OEM cooling fan shroud on the 05-10 & 11-14 non-GT500 S197 cars.
This is where Ford found that w\ the stock OEM cooling fan design when at speed airflow thru the lower 15%-20% of the radiator (radiator section below the lower hose outlet) gets somewhat impeded due to air oscillation in this area while the cooling fan is windmilling thus reducing some overall radiator cooling capacity so Ford engineers designed these trap doors into this 13-14 cooling fan shroud to alleviate this issue by giving the air in this section another way out of the shroud instead of going thru the fan so the lower 15%-20% of the radiator's cooling capacity can be fully achieved at speed but will close up & reseal the shroud to alleviate air recirculation back into the shroud so the 7-blade cooling fan can retain maximum air draw thru the radiator\condenser\intercooler at low speeds.

It is these trap doors along w\ the 7-blade fan that gives this 13-14 GT500 cooling fan assembly (M-8C607-MSVT) it's superior overall cooling advantage vs the OEM design.........

After all they were trying to keep a 5.8L 662hp SC'd 4V Trinity Modular V8 cool using the same OEM sized radiator dimension-wise....... With the 4.6L 3V\Coyote Modulars this wasn't considered to be an issue cooling wise........but w\ this 13-14 GT500 cooling fan assembly installed in tandem w\ a 4.6L 3V or even a Coyote you will be able to get the absolute best airflow\cooling capability from a fan\shroud assembly on these 05-14 S197's AND retain Ford OEM fit\design.

A win-win scenario IMHO.

This Ford M-8C607-MSVT cooling fan assembly IMHO is tailor made for corner carvers as well as FI...........if getting maximum cooling capacity from your radiator is desired, whether you're using the OEM radiator or an aftermarket 1.

1 more thing to know.......
If you're planning to install this 13-14 GT500 cooling fan in a 05-10 S197 w\ the hydraulic power steering reservoir still mounted on the cooling fan assembly just know that you will need to do a little trimming on a section of shroud reinforcement to allow the reservoir to properly mount to it as this assembly was designed for S197's that came factory equipped w\ EPAS steering racks. Other than this it is plug & play. 11-14 is fully plug & play as all come equipped w\ EPAS steering so no modding is necessary.

Not trying to sell it, just pointing out all the improvements.....................