Ford Expedition Towing Problems

colliehauler wrote:
That's exactly what it is supposed to do. Modern gas motors make their power at higher RPM. It's harder on a motor to lug it at low RPM when towing.

EXTREMELY DANGEROUS to tow without trailer brakes and illegal. You need a trailer brake controler installed in your vehicle for them to work as well. Most states require trailer brakes on anything over 2000 pounds, you are close to three times that amount. A lot of trailer tires are only rated for a max speed of 65 as well.

X2

You doubled (or more!) the load your engine was dragging up that hill, so of course it will have to work harder. 3500 rpm for a gas engine is not at all unusual when you are working one hard. I assume you have a mechanically driven water pump on that engine (most are) and if so, you NEED it running fast in order to pump enough water to keep the engine from overheating. Most car/truck gas engines red-line in the neighborhood of 6,000 rpm, so you are well below maximum output.

As for the trailer brakes, as others said, absolutely required, both for safety and legally. If you had a wreck (heaven forbid) and it came out that your trailer brakes had been inoperative, The Powers That Be™ would be all over you like a cheap suit. You absolutely must find out why that wire is cut, fix it, put a house battery on the trailer hooked up to a breakaway switch, and get/use a brake controller in your truck.

Assuming the previous owner didn't add 5,000 lbs to the trailer in modifications, you should be well within the truck's capacity. Do be aware that you are more likely to exceed the truck's payload than its towing capacity. I would heartily recommend finding out what that payload limit is, and making sure that tongue weight, passengers, fuel, and "stuff" in the truck do not overload it.

But, yes, indeed, towing will require your engine to rev higher and work harder than not towing.