poontanghooligan

Oh I'm owning it for sure! One of my favorite engineering quotes: "When you want to know how things really work, study them when they're coming apart." I DID look at the ST but dang they were $10K more than the limited. But they are very quick! With just a tune they're running low 12's. Perfect for towing. I wonder what the ST would do in the 1/4 with a 5k trailer. 18-20? I do wish I could have made the Edge work. I put a bit of work into it but I got $40k on trade in so it made sense for the deal overall. 5-Star tune is on it's way for the 2.3. Gets close to the stock Edge ST crank numbers on 93 at the wheels.

Well folks, I did what I said I wouldn't and traded in the ST for a 2021 Explorer Limited 4WD with the 2.3 and 10 speed. After looking at the cost of installing the heat extractor and electric PTU pump and cooler, I was looking at $2K and that's without knowing if I could make the PTU live while towing at the limits. I did a lot of research on the drivetrain of the Explorer. The RWD bias design, transaxle and FDU are in a much better arrangement in terms of heat generation and cooling. The RDU is a little beefier as well and the transmission (10R60) is rated at 442 foot pounds (600 nm), which it way more than the 310 foot pounds the 2.3 puts out. So towing longevity should be improved a lot. Once I get passed the break in mileage, I'll do a towing test with underhood temps and Forscan as a comparison then report back.

I'm not sure if there is a water-cooled version of the 2019+ PTU for the 8F57 transmission. Information about anything new from Ford is hard to find sometimes. I'm not having any issues when just cruising at highway speed and I do see the RDU is not getting any power transferred to it in the AWD message display. It's only when AWD is fully engaged, i.e., 50/50 split of power, while going up a long grade under high boost. That's when the PTU temp gets too high and the RDU is disengaged. The driveshaft is still spinning but the RDU clutch is fully disengaged. I also see this in the AWD message display.

Just wanted to make a correction about me saying my '20 ST PTU being water cooled. Turns out mine is not. It has the mounting boss and bolted cap but no cooler. It's likely because it's US spec and not for hot climates. Now I wonder if I could source the parts to retrofit the cooler. Seems like it would be a better route than an aftermarket oil cooler and pump.

I shall endeavor to strive for greatness in all that is PTU cooling. BTW, I am also an engineer so these "problems" are just issues to solve. With a little ingenuity and testing (like you've done so much of!), thy will be done!

My thought is that by combining the heat extractor and PTU cooler, I'll get the temps under control. Should be able to increase oil capacity a fair amount too between the lines and cooler. The ST tows so well in almost all cases that I loath to give up so easily, especially because of the plans I have for it. Thought about a new Explorer but they aren't rated for much more. Only 5600 lbs with the most expensive trim and engine configuration (ST). Just not worth it. They are WAY overpriced. And I don't really want a truck. I suppose the Ranger could work but not nearly as roomy in the back seat. F150's are WAY overpriced as well.

Thanks for your input! In my case, data showed the PTU sump temp was fry high. I was able to get some data on the way to the campground yesterday. "AWD disabled" message only triggered once and that was at the top of a long grade (4700 to 7400) passing a slower truck and trailer. Otherwise no issues. Ambient air temp: 82F Air inlet temp: 102F to 105F CAC temp: 145 F to 152F Boost level: 7-12 PSI (during climb) PTU disconnect temp: 265F (yikes) PTU reconnect temp: 255F Engine coolant temp max: 225F (not during AWD disabled) Transmission temp max: 220F Under hood temp near air intake snorkel (just to the left) max: 204F Under hood temp near battery max: 198F Under hood temp near intake idling: 179F Under hood temp near battery idling: 168F The PTU just heat soaks and never recovers much until load is reduced. So I'm also looking at an oil pump to circulate the PTU oil through a small oil cooler and temp-activated fan. Also looking to install a 2014 GT500 hood heat extractor. Body shop says they can shape it to match the hood lines so I can place it nearest the front for best low pressure heat extraction. Pushing the Edge limits!

IIRC, the PTU cooler get its coolant AFTER the coolant has been run through the engine. If this is the case, then running at constant higher boost levels is going to add more heat than normal to the cooling system and that hotter coolant is then going to the PTU cooler before going back to the radiator to be cooled. Even with a lower temp thermostat, the temp at which the coolant is at higher boost levels is going to always be above the t-stat opening temp. A lower temp opening might delay PTU max temp but only for a short time I suspect. I guess it's a matter of priority by Ford engineers as to what gets cooled first. Cooling the PTU first wouldn't add much heat to the overall cooling system before coolant goes through the engine. But sadly it's the opposite.

Likely because I was pushing a lot of boost, around 12-14, for a long time at maximum GVWR and GCWR in 90+ temps. That's probably not a normal use case. Even tracking the ST doesn't generate the same continuous load. The good thing is that the protection measures kicked in. There were no other issues and I was able to continue along with the same load without overheating. Good thing it's an ST because it has the larger radiator. In reading other Ford forums (Explorer, Bronco), the AWD disabled issue seems to happen on occasion, like going up long steep muddy hills and flogging in sand. This can generate a lot of PTU heat, or heat in general. Again, probably not the most common use cases for these vehicles so they don't get tested this way. Or maybe they do but those results aren't "public".

Going off of this PDF for the 2019 ST, it shows a PTU cooler: 2019 ST PTU Oil Change. To be honest, I haven't verified my 20 has it but I would think there wouldn't be any change from the 19 to the 20. I'll crawl under there and check though. I have some temp probes coming in a few days and will get some data on under hood temps. I also have the ODB adapter coming so I can Forscan. Good suggestion on the grill but the ST does have a honeycomb grill which is substantially more open than a non-ST grill. Now the meth fogger could be something to tinker with! I have learned that the AWD disabled message is a result (at least in my case) of the PTU starting to reach it's max temp limit so the RDU is disconnected to avoid overheating the PTU. The PTU never gets the chance to overheat because of this protection. Once I'm done climbing a long hill towing and boost levels are lower, the AWD is re-enabled and all is good. Will be interesting to see the PTU temp when this happens.

In an effort to reduce under hood operating temperatures on my ST, I'm going to install a hood heat extractor from a 2010-2014 Mustang GT500. Seems like it will look good with the Edge's hood lines (and hopefully very functional!). I'm not having any overheating problems save for the occasional "AWD Disabled" message when towing my trailer in hot temps (90+) up long grades. My thinking is that since the PTU is water cooled and my ST is under quite a bit of boost going uphill with a big load (with A/C on), I can reduce the load of the cooling systems by extracting the ridiculously hot air under hood. Instead of the hot air from after the radiator trying to find a way to escape, some of it will just go straight out of the extractor, hopefully reducing the heat load of the engine and trans enough to let the PTU operate within a safe range. That's the theory anyway. So a couple of questions: 1. Anyone measured under hood temperatures with the 2.7? I would like to have before and after numbers to see if this mod is effective at heat extraction. I can always measure myself (unloaded and loaded) but am interested in anyone else's experiences too. 2. I am going to mount the extractor with the front edge of it lined up with the back of the radiator, basically in the gap between the radiator and the engine. This should provide the best low pressure area for extraction and, because of the angle of the extractor holes, allow for the most air to exit. Does this sound effective both in placement and best efficiency?

Hey @Snoking. A little late but I use this brake controller towing my camper: Curt Echo Wireless Trailer Brake Controller. Going wireless avoids having to mount a controller inside. There aren't too many places to mount one that's within reach without it looking ugly. Just have to run a power wire from the battery to your 7-pin. I used this kit: Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires. I went 10 gauge because of the long run from the battery.

Nice! You have much less drag with that setup. While there might be "intended" towing, I am within all manufacturers specifications for my setup. I'm not trying to justify doing something I shouldn't. And overall, the trip went great. I had all the power I needed, braking was really good and handling was what I would expect when towing a trailer. I have a lot of towing experience (30 years) with many RV's and vehicle combinations. None of the vehicles were AWD though. So my question was around why the AWD was disabled under specific conditions, like starting up a grade. If the RDU is overheating and I am within manufacturers specs, then Ford's RDU cooling capacity is overrated.

Hmmm...I don't see why either is wrong. I am within the manufactures limits on tongue weight (340 now), max trailer weight (3280), frontal area of trailer above vehicle roofline not exceeding 30 square feet and GVWR below 5700 lbs. The trailer also has dual axels with electric brakes. The ST has additional cooling capacity as well. I'm also following the special operating conditions maintenance schedule as outlined in the manual. So how is what I'm doing wrong?

Yes it was working hard for sure. However, I've learned that there are specific safety measures taken by the ECU to ensure conditions don't allow for failures to occur, within reason of course. The RDU is disengaged if it can't be kept cool enough which might the case in my situation. Still don't know without knowing temps. In most 4WD (not AWD) vehicles, you don't get this kind of management by the ECU. It's mechanical and up to the driver to manage so in a rear diff overheat situation, it's the gear oil burning that lets you know you have a problem. Then it's too late.