Hello, I just bought a 97 F-350 4x4 Dump Truck with 7.5L V8 OHV 16V engine. I am looking to breath some new life into her pretty cheaply. The current exhaust is rusted so bad it became disconnected by rust completely near the cat. I am hoping this is why it was running rough when I stepped on the throttle and it would chug. Any thoughts on this?

Anyways, I am thinking replace the exhaust with another stock one unless I can get something pretty cheap aftermarket that would give a good power upgrade of at least 20HP.

I also am going to add some Seafoam to the fuel and engine oil to renew whatever it can.

I plan on changing the plugs and wires as well as the air filter. Is a Cold Air Intake worth about 20HP and/or extra fuel mileage? What brand and model plugs and wires should I get?

I calculated I was getting about 7MPG on my 160 mile ride home and the gas tank only filled up to about 15 gallons? Isn't the tank bigger than this? Is there a 2nd tank? 7MPG just seems ridiculously low, and I'm hoping the huge break in the center of the exhaust had something to do with the poor fuel mileage.

There is a switch about 1 inch to the left of the main light switch on the left side of the steering wheel and that switch is permanently in the up position and it is riveted to permanently be in that position from the previous owner. What is this switch? Where might the switch for the 2nd gas tank be?

Please let me know any other tips you can give me to get my baby purring again. Thanks!

 

you just got this truck? then let me be the first idiot to tell you they quite making 351's in 96. bet your gonna try telling us next that its speed density, and not obd2. and dont even try telling us it has the same body as a 96, everybody knows 97 started the ranchero-looking body style. get used to hearing that ****, cause thats what most people think. but not me, i beleive you, my donor truck for my swap was a 97 f250hd, with a 351, zf 5speed. of course i swapped the 5 speed also. so, i finally find somebody with the same engine as me. i went with a hooker dual exhaust kit, which i modified extensively to suite me, and i welded in a bung to install the 02 sensor before the cat(s). im still kicking myself for not putting long tube headers when i swapped it in. maybe your cat is plugged. theres an ignition tune up the guys on full size broncos are doing. and be ready for the dude at the parts counter to insist your truck doesnt exist.

 

I'm not sure what to make of your post. I checked the VIN online and that is what multiple websites tell me the engine is so I'm sure it's correct.

 

I'd go through the truck top to bottom and give everything the once-over. Fix the exhaust, no need to go crazy (it is a heavy dump truck after all). Intakes and whatnot are generally a waste of money on these trucks, the 460 and 300 already have the better intake (as opposed to the 302 and 351 on top of the radiator). Motorcraft or Autolite plugs are preferred, get a decent cap and rotor with brass terminals. These trucks usually have two tanks, yours may have been modified by the PO at some point. Single digit mpg is a way of life for 460 owners, sad to say.

 

why are you talking about a 351? this truck has a 460 in it... 7.5 l is a 460

 

you have this:
351 cu in (5.8 L)
The V8 Ford Windsor motor family is considered by Ford enthusiasts to be one of the greatest[2] and most successful[3] engines produced by the Ford Motor Company. It is referred to as the Small Block Ford by major aftermarket auto parts companies,[4] parts catalogs,[5] on internet forums,[6] and by Ford itself.[7][Note 3] Introduced in 1962 as part of Ford's "Total Performance" era,[8] the Ford Windsor design succeeded the Ford Y-block engine family, rendering the latter obsolete for performance purposes.

Ultimately, in 1991, Ford began phasing out the Windsor engine and replacing it with their new 4.6 L Modular V8 engine. In 1996, Ford replaced the 5.0 L (302 cu in) pushrod Windsor V8 with the Modular 4.6 L in the Mustang. Its use continued until 1997 in the F-150 pickup truck, and until 2001 in the Explorer SUV.

From the mid-1970s through the 1990s, the Windsor engine was also marinized for use in smaller recreational boats. As of 2008, Windsor engines, including the 5.8 L (351 cu in) and 5.0L 302, are still being manufactured; available as complete crate motors from Ford Racing and Performance Parts.
Ford Windsor engine - Wikipedia, the free encyclopedia

the '96 f150 was the last yr for the 9th gen.the '97 f150 was the first yr for the new 10th gen model.
the f250 and f350 were still all 9th gens in '97.



he has this:

460 cu in (7.5 L)

The 460 was phased out for use in passenger cars in the late 70s, but continued to be produced with minimal modifications in trucks, RVs, and Boats until it's production ceased in 1997. The 460 is a great towing engine. The 460 actually had higher horsepower and torque ratings than the IDI 6.9 liter and later 7.3 IDI diesel engines, though fuel economy was significantly better with the diesel. The 460 began using fuel injection in 1987, leading to a slight increase in horsepower and torque ratings. 1993 and up 460s saw an improved cylinder head design that further improved power. While perhaps best known for it's poor gas milage, the later 460 is considered by most to be a reliable, long-lasting, heavy-duty, and powerful engine for towing and hauling purposes, as well as a good starting point for engine builders building dragsters. Due to it's mass production and relatively minimal changes during it's 30 year production run, parts are generally cheap and easy to find for the 385 series engines.
Ford 385 engine - Wikipedia, the free encyclopedia


ArlyDude,
don't feel bad about your 7 MPG.
most get 6-8,with a few reporting 10-12 (and those are rare) and only a handful of people (running them like cars on the hwy,empty) report low teens (most feel an error in calculating or ... something lol.)
so all things considered that's pretty good.

many claim to push high teens and even low 20's (running them like cars on the hwy,empty) with a factory bed and their 6.9l/7.3l idi diesels.
with my DRW dump i can't match their economy reports either.driving as slow as possible has helped though.
my average is 14+ mpg (US)
nothing like a standard srw pickup diesel can get no.but then again we can out haul their little factory setups.

 

Yes that switch should be a second tank, but like said before, it may have been modified for single tank with that dump setup. Depending on the weight of the dump setup, you might** be able to squeeze out a few more mpgs. If you have exhaust probs start there. Don't mess with headers.. more headache than help, imho. You can get good high performance catalytic converters for $50 online. If you need it and live in an emission state get a new cat. Find a local good exhaust shop and you should be able to get a new cat, tubing and muffler for a reasonable cost. Where I live It would be less than $300.
Do a full tuneup and don't use cheap plugs. Go motorcraft. Try running some upper intake cleaner and maybe some oil cleaner. BG makes some good stuff. Good luck and let us know!

 

Sorry about that, I got this thread mixed up with another thread. I hope I didn't cause any confusion for the MP. Actually, got this thread mixed up with one from a differant site entirely. Good luck with your truck, and I appologize for any confusion.

 

Actually your the second.....

 

Nope.. short of being clogged the exhaust system will have no effect on how well the engine runs you have other problems, so pull the codes, check for vacuum leaks, check fuel pressure, and give it a complete tunup with all new ignition parts.

DO NOT put a stock exhaust back on the truck unless you want even less power, replace as much of the stock system as possible with aftermarket performance pieces and not cheap muffler shop junk.

How did you calculate this? 160mi divided by 15 gal equals 10.6mpg, you cannot use the fuel gauge to calculate milage.

 

Believe me, I'm smart enough to use real numbers when I calculate. I did it from fill up to fill up and divided the number of gallons with the mileage.

 

Happens in the best of families.

 

Not sure where you got that you'd gain 20HP from a CAI? Maybe 3-5HP max. The engine itself doesn't breath good enough to warrant a better intake.

Start with a full tune up:

Fix Exhaust
Plugs
Wires
Air Filter
Fuel Filter
Check for any error codes

 

7MPG is not bad in a dump truck. Figure it weight about 8000lb empty and the cab shield is a parachute.

I hope you dont think you are going to get 12mpg

 

What gear ratio? 4.88? Likely?

With 4.10 gears, you might eek out 10 mpg with easy driving. The deeper the gear, the worse it is going to get. You load heavy? Gets worse. Even in OD and keeping around 55 mph it will drink fuel. Try to run it at 65 mph and it will evaporate.

Likely someone either
A: locked out the back tank due to leaks/bad pump/removed all together

B: due to dump install(likely A)

Should be a second tank behind the axle, with a filler tube coming up to side of bed area. Front tank comes up in front of rear axle.

Run standard Motorcraft parts(plugs, wires, cap, etc). It should have twin air intake tubes from filter to throttle body. Take it apart at the middle junction and note the restriction on the one side(think it's on air box side?). Using hacksaw, cut it off leaving enough to reattach hose. This will let it breathe better.