Rear axle temp reads -20

[That_Orange_350]

I recently changed gears in my boosted 350 and noticed my diff oil was black and burnt like liquid tar. I have done one track day and some spirited driving. That got me to thinking that if my axle temp wasn’t reading correctly then it wouldn’t trigger the pump to turn on. I remember the temp being negative before but not certain if it was before the whipple or after. My tuner says it’s a known fault and Ford doesn’t have a fix. I searched online but didn't get much help. I have forscan and HP tuner software but haven’t had sufficient time to plug either in. I replaced the diff sensor and it read 2° more negative. Have any of you run into this problem or heard anything about it ? TIA for any help or insight to this problem.

Sponsored

 

[Skye]

I was interested in the topic and found some reference materials that might be of help.

https://www.mustang6g.com/forums/threads/oem-differential-cooler-pump-failure-on-gt350.184833/

I understand the sensor has been replaced. I was curious what it looks like, to include the inside. The thread does detail FORScan-and-pump interaction.

https://www.mustang6g.com/forums/threads/oem-differential-oil-cooler-install.69499/page-7

https://www.mustang6g.com/forums/th...-cooler-early-tech-pack-car-questions.187161/

More worthwhile, ^ some wiring diagrams.

Finally, I'm attaching what appears to be a t-shooting guide for the pump.

Good Luck.

 

[JohnVallo]

The Black residue in the rear-gear oil is pretty normal.
This is just a result of the Black Oxide coating wearing off of the Ring and Pinion.
Ford doesn't see this as a problem.
I've had 7 or 8 different GT350 Torsen rears apart and they all look like this. (Pretty nasty looking stuff). I have always refilled mine with BG oil, and never had any problem.
I think I wrote about it in this Thread:
Inside the "Super 8.8" Rear End | 2015+ S550 Mustang Forum (GT, EcoBoost, GT350, GT500, Bullitt, Mach 1) - Mustang6G.com

As far as the Axle Temp gage reading wrong problem, I have the exact same thing.
Only after I installed my Whipple (Which I used the Whipple tune also), did my Axle temp gage read almost exactly -100 degrees different from actual temp. In other words, it would start-out at -15 cold, which would be 85 degrees, Then go to +40, which would be 140 degrees.
I have called Whipple about the problem and they say: Nothing we can do about it, (No fix available), so I have gotten used to it.
I have tested several different gear ratios in my GT350, Currently running 4.11, which I really like.

 

[That_Orange_350]

I was interested in the topic and found some reference materials that might be of help.

https://www.mustang6g.com/forums/threads/oem-differential-cooler-pump-failure-on-gt350.184833/

I understand the sensor has been replaced. I was curious what it looks like, to include the inside. The thread does detail FORScan-and-pump interaction.

https://www.mustang6g.com/forums/threads/oem-differential-oil-cooler-install.69499/page-7

https://www.mustang6g.com/forums/th...-cooler-early-tech-pack-car-questions.187161/

More worthwhile, ^ some wiring diagrams.

Finally, I'm attaching what appears to be a t-shooting guide for the pump.

Good Luck.

The temperature sensor isn’t actually in fluid. It’s inside an enclosed hole. You can remove it without losing any fluid.

 

[GTP]

I have a Setrab thermal switch in my DIY diff cooler build. It is 2-wire and if I jumper it out (short the 2 wires) it will start the fluid pump even when cold. I just have to have the car on and not running.

I have the exhaust around the diff double heat wrapped, and I run 75w140 gear old exclusively. The oil is dark when I change it annually (4-8 track days) but it is certainly not black.

 

[That_Orange_350]

I have a Setrab thermal switch in my DIY diff cooler build. It is 2-wire and if I jumper it out (short the 2 wires) it will start the fluid pump even when cold. I just have to have the car on and not running.

I have the exhaust around the diff double heat wrapped, and I run 75w140 gear old exclusively. The oil is dark when I change it annually (4-8 track days) but it is certainly not black.

Does it not work when the car is running ?

 

[GTP]

Does it not work when the car is running ?

No, it is just easier to hear the pump running. I chose a minimalist approach to my build, which uses the smaller and very quiet Marco pump.

Also, my diff temp gradually increases to 230F on track where it then stabilizes.

You can also put a max temp sticker on the diff housing for a second opinion.
OP Mustang sells them for $5. Ask Tim to send it in an envelope instead of shipping.

 

[mavisky]

That's weird. My car is tuned via HP Tuners and an RTD tuning device and I have 0 issues with the rear diff temp displaying correctly. Had to go back to check my latest autocross runs, but sure enough it's sitting there showing 170 degrees just fine.

 

[That_Orange_350]

That's weird. My car is tuned via HP Tuners and an RTD tuning device and I have 0 issues with the rear diff temp displaying correctly. Had to go back to check my latest autocross runs, but sure enough it's sitting there showing 170 degrees just fine.

I think I’ve figured out it’s the whipple stock tune. Another member has the same issue and my tuner said it’s a known problem with whipple.

 

[That_Orange_350]

The Black residue in the rear-gear oil is pretty normal.
This is just a result of the Black Oxide coating wearing off of the Ring and Pinion.
Ford doesn't see this as a problem.
I've had 7 or 8 different GT350 Torsen rears apart and they all look like this. (Pretty nasty looking stuff). I have always refilled mine with BG oil, and never had any problem.
I think I wrote about it in this Thread:
Inside the "Super 8.8" Rear End | 2015+ S550 Mustang Forum (GT, EcoBoost, GT350, GT500, Bullitt, Mach 1) - Mustang6G.com

As far as the Axle Temp gage reading wrong problem, I have the exact same thing.
Only after I installed my Whipple (Which I used the Whipple tune also), did my Axle temp gage read almost exactly -100 degrees different from actual temp. In other words, it would start-out at -15 cold, which would be 85 degrees, Then go to +40, which would be 140 degrees.
I have called Whipple about the problem and they say: Nothing we can do about it, (No fix available), so I have gotten used to it.
I have tested several different gear ratios in my GT350, Currently running 4.11, which I really like.

Whipple just emailed me and said they have the issue fixed. I need to send my vin and tomahawk serial number.

 

[Inthehighdesert]

Good to see they got that sorted. I had the same issue on my 20 with their setup few years back. It’s taken them awhile to come up with a fix. It was just on their tune from what I understood at the time. They were supposedly working with a Ford Engineer.

Whipple just emailed me and said they have the issue fixed. I need to send my vin and tomahawk serial number.

 

[That_Orange_350]

Good to see they got that sorted. I had the same issue on my 20 with their setup few years back. It’s taken them awhile to come up with a fix. It was just on their tune from what I understood at the time. They were supposedly working with a Ford Engineer.

I installed the tune today and I can confirm it is fixed.

Sponsored