Engine loud going uphill under load

[Daryles]

2016 F350 7.6L Powerstroke turbo diesel dually.
We went from Banff to Jasper Alberta Canada on route 93. Along the way, north of Saskatchewn river crossing there's a place called big bend. After the bend the road climbs STEEP and LONG. I have no idea what the grade was, but it was STEEP!!
About 1/2 way, the engine started roaring. It was like a valve opened (or exhaust pipe was removed) and it got loud.
We pulled over at the next pull out.
As I let off the pedal the engine returned to normal. All instruments and temperatures were normal. We sat at the pull over for about 20 minutes then continued the climb. About 1/2 way up this part, same thing.
Again we pulled over at the next pull out.
Again as I let off the pedal the engine returned to normal.
Normally we dump our tanks before getting on the road however we have been dry camping in the NP here and the tanks were about 1/2 full. Maybe an extra 400 lbs?
We will definitely dump before going over that mountain on the way back.
My question is, is there some kind of bypass valve or overload valve under there that opens up under heavy load?
Already looked in Ford forums and our forum. Nothing.

[MandK]

Sometimes when the temperature rises a bit the fan clutch engages and that can cause a bit of a roar. The temperature may not rise enough to notice it but the sensors do. Other than that, I have not run into that issue.

[Theunz]

What Mark says. When the fan kicked into my 05 Ford it sounded like afterburners! It’s just doing it’s job.

[Carl n Susan]

I agree with the previous posters. When the engine gets warm, and pulling a steep grade will do that, the fan kicks in and IT IS NOISY! Watch the Temp gauge. When it gets over halfway is when the fan starts to kick in.

This is normal behavior and nothing to worry about.

[rohrmann]

And the Chevy does the same thing. I would be worried if the fan clutch didn't lock up and make the fan noise when climbing a hill.

[Daryles]

Thanks everyone.
Next time I'll try popping the hood and check the fan real quick.

[RMcNeal]

I was thinking maybe it was going into a Regeneration cycle on the DPF filter, but the explanation above sounds more likely.

[mlh]

Like all the post above your fan kicked in. Your truck is doing exactly what it should do. Your gages didn’t show you the temperature was rising because they also did what they were designed to do, near nothing. You can get a set of real gages that will tell you what is going on with your truck. They plug into the OSB port that is located under the dash on the drivers side of your truck. Your truck is putting out dozens of signals that you can read with the proper gages. Most you have no use for but some are very useful, temperature for the engine, transmission, coolant and oil. Just to name a few.
Lynwood

[JamesDean334]

What you're hearing seems 'normal' under heavy load conditions. You can download the Forescan app (Android or iOS) and get an OBD-II Wi-Fi or BT dongle from Amazon that plugs into your OBD-II port. The dongle, when connected to your smart phone or other Wi-Fi capable device, and the app is properly configured to monitor the appropriate parameter IDs (PIDs), will display digital 'gauges' on your device to let you keep an eye on critical data that's coming to/from your truck's ECM / PCM in real time. The Forescan app will also record the selected PID data for review later, should it be necessary for diagnosis purposes or just because you'd like to know how your truck is performing.

[Foldbak]

It was definitely the afterburners!

[BB_TX]

Like the others above, my 2007 6.0 fan would sometimes sound like a jet engine under high heat and/or heavy pulling. Gauges normal. And it would stop when I slowed down. But my 2012 6.7 never did.

[mhs4771]

Yep, first time that Cooling Fan kicks in it will scare the bee jesus out of you

[C&P RV]

I will never forget - 2002 F350 with the 7.3 Powerstroke - I-10 west between Tucson and Phoenix in about a 30 mph headwind towing a 2002 Fleetwood Prowler 5th wheel, hot as heck outside and that fan clutch engaged!! I thought I'd blown the engine.
FORSCAN will give you the ability to also add info to the gauges in some cases. On my 2017, I now have the digital water temp displayed above the needle gauge. I can also monitor the regen cycles. As JamesDean344 said you can monitor a lot of info on your phone. I put the app on an old android phone and can run it full time to monitor much more info than what the gauges display.