Finbar

I just bought a 2007 5.4L supercrew 4x4 3.73 ratio limited slip axle and tow package. I bought it primarily to tow our travel trailer which is 34' and weighs 6,600 dry and empty. I towed for the first time this weekend and I have to say I was disappointed as the truck seemed to have a tough time pulling it.

First question, what exactly is the gvwr on the truck? There are so many websites and forums that give different figures. I was always under the presumption that it's 10,500. The sticker however says under Optional Equipment "3.73 Ratio Limited Slip Axle 7200# GVWR package" Does this mean I bought an underpowered truck? When towing, should I turn the overdrive off? How much of a difference should I expect?

Next question. When I turn the engine off there is a distinct hissing sound coming from under the hood. I mentioned it to the dealer when I went to pick up my plates and they said the truck was decompressing and that it was normal. Is it?

Your thoughts/advice/expertise are greatly appreciated.

cgaskins

Well you ask a good question. Follow this link over to f150online.com and follow this thread on towing and a F150. About half way down the 1st page is a post by "Colorado_Camper". He does a great job of summarizing up this question / situation.

http://www.f150online.com/forums/sho...d.php?t=310464

This was the exact same logic I used in selecting my New 2008 F150 SuperCrew Lariat. I have the 5.4, 3.73 rear end, factory tow package and the 20 inch wheels. I have a Cherokee Lite Travel Trailer (30 foot) that has a dry weigh of about 5400 lbs. (Loaded I anticipate I am at about 6800 lbs) Since my '08 F150 is brand new I have not towed with it yet, but I anticipate it working perfectly. I had previously towed this trailer with my 2002 F150 SuperCrew. It had the 5.4 engine (2 valve, not the newer 3 valve) and a 3.55 rear end. It was acceptable with the caveats listed in this thread. My gas mileage was between 7 and 10 mpg depending on the terrain. I generally tried to keep my RPMs below 3000 which made a huge difference in fuel economy in my 2002 F150. However the 08 has about 60 more horse power and about 45 more foot pounds of torque.

I anticipate camping about once a month so that would be less than 12% of my miles per year towing. The F150 makes the best sense. Plus it looks great and rides great as a daily commuter. My 02 got about 13.5 MPG on my 10 mile commute to work. My 08 is better getting about 14.7 on the exact same commute.

johnm1

Finbar, I have a 2007 F-150 5.4 Supercab and can only comment on towing a motorcycle trailer with no problem. Very light and not a good comparison to your towing situation. I, too, have a distinct hissing sound when the engine is turned off. Any other members have the same noise?

TexanFX4

I have the hissing sound also, but I have never paid it any attention. I guess I have a different situation than everyone else. I am starting to wonder if my truck will even think about towing 8200K TT or lighter (6500K or so) 5th wheel. I'm thinking the shortness of my truck is really going to be a problem.

driver444

You did NOT buy an underpowered truck. It should handle what you want to do without a problem. You really have to expect that when you are moving more than double the weight going down the road that it's gonna slow you down a bit on the take-off and the hills.

I have a supercab 5.4 with 3:55 gears, 7200# GVWR, and I believe 14,000GCWR, and have towed a trailer right at my rating of 8400#. It did what I consider to be great!

As far as towing in overdrive, I typically don't. If it was a 2-place ATV trailer I would, but anything heavy, and it's gonna be doing alot of unnecessary shifting, and causing alot of heat to build up.

The hissing is normal.

driver444

That post that CGASKINS linked to in the 2nd post to this thread is right on. I couldn't have said it any better.

Think of it like this. I drive 18-wheelers for a living. They have a towing rating of somewhere around 40 tons (we pull 48 foot tandem trailers loaded with 20 tons a piece, plus the weight of the equipment). It doesn't mean they'll pull those two trailers up a mountain at 60 MPH. In fact, on the New York State Thruway, there's places where we get down to 25-30 MPH.

I think we get so accustomed to driving the speed limit and above that we forget it's the "speed limit", and not the "required speed"!!

Also, This is for "FINBAR"... I replied to your last post about 5th wheels. Tractor trailers are a great example of that. You could NEVER pull a 53 foot trailer weighing 45,000# off the pintle hook of a 16,000# tractor, not because of power, but because the trailer would throw it around, and when you hit the bakes, it would push you. But with all that weight on the drive axle(s), it's a different story.