Hey fellas,
With fuel prices at $4.15, I figured it was time to start a thread to help some fellow IDI brothers out this summer Don't ditch vacation because of fuel costs!

To start, the idea is to be sure your truck is running as efficient as possible. Time to invest a little bit of cash into your truck with some maintenance and performance upgrades.
Start with the basics....

Tires: Read the recommended PSI on your tires and make sure your tires are what they recommend, and that all 4 are matching. For the 4x4 guys, those aggressive tires might be robbing your MPG's a little, but there's no way around that since all 4 need to match.
For us 2wd guys, a nice set of highway tires will definetly get you the best MPG's you can squeeze out of your truck. My truck has 225/75r16's on the front..with a highway tread. My rears are 235/85R16 with a highway tread. They absolutely SUCK off road, and I often get stuck in my front yard on wet grass with a patheticly small slope But they can't be beat on pavement!

Wheel bearings: It might be a good time to re-pack your bearings. It may not gain any MPG's, but it will free up any rolling resistance if they haven't been serviced in a long time. For those of us who have only owned our trucks for a year or two, you may not even know if there is grease in there I've seen my share of bearing issues due to a lack of grease. Not fun!! My favorite job was when the race wouldn't come off the spindle on our Jeep CJ...I had to use the 4" angle grinder and slowly grind the friggin race off! That was a bad day, with many bleeped out words... I mean the actual bearing had gone to crap. The "cage" holding the roller bearings broke, one of the roller bearings ate itself, because the gap was evident when all the other roller bearings shifted...

Brakes: This would be time to make sure your front calipers are greased so the caliper can slide easily on the caliper bracket. You'd be surprised when the calipers aren't allowed to slide freely, they can burn up just one side of pads or hang up and drag...reducing MPG's.
The rear drums can be adjusted very easily. On the bottom of the backing plate, there is a small oval rubber plug. Use a flat screwdriver and pry this plug out. Then you can stick a flathead screwdriver in there to probe around. You'll feel a gear-like thing. That's the star wheel brake shoe adjuster. To adjust the rear brakes, you pry the screwdriver against the backing plate and spin the star wheel either up or down.
Spinning the starwheel UP means pushing the screwdriver DOWN and that will TIGHTEN the rear brakes. The idea is to adjust the brakes so they are JUST beyond dragging when you spin the truck wheel by hand.

King pins: I don't know if ball joints are greseable But I know the king pins on my 85 are. While this won't help relieve any rolling resistance, it's only one more thing to do while you're in there. Hit the tie rods while you're at it!

Driveshaft: Grease the U-Joints. It may not reduce much rolling resistance, but it will help you out anyways.

Transmission: Whether you have a NP435, T18, T19, ZF5, C6, or E4OD...check your fluids and make sure they're in good shape!
For the 4 speeds, they require standard 80w-90 gear oil...top if off.
The ZF5 manual takes ATF...top if off.
The automatics...well I have no clue. But give 'em a flush and a fresh filter for good measure. It'll help the transmission live longer, and it will definetly make your truck feel younger

Transfer case: Well....I don't know much else except that the BW1345 and BW1356 use ATF...anybody else can chime in here!!

Air filter: If you've got a standard paper filter, replace it if it's dirty. They're cheap enough that the extra fuel you burn due to a dirty filter will make you cry. I'm running on a nearly brown filter , I threw my last used filter in today...which is dirty anyway, but it already made a big difference in the go-pedal

Engine oil and filter: Check to make sure you're full to start with . But be sure you're topped off and the oil is changed regularly to ensure you're losing as much friction as possible.
Using the 7.3 Powerstroke oil filter might help a little, since it holds an extra quart of oil. Not sure if that will help MPG's, but it would theoretically give 1 extra quart of oil to extend the life of the oil in terms of friction Motorcraft P/N FL-1995
Truly, this isn't the end of the world. My 15k mile oil change didn't seem to effect me too much. I mean, you gotta think that since I burn about a quart per week, the oldest was about 8 weeks old

Fuel filter: DUH! Why is this last? For the 6.9's, change that puppy if it's been a while. When you install it, fill it up with Power Service additive (white or grey bottle, I can never remember...read the bottle and judge for yourself). I fill mine up with ATF, but it's sort of a soft spot here on the forum. The red dye in the ATF can be similar to off-road fuel. And since the fuel system returns whatever isn't burnt back to the tank, it will make your whole tank red. If you get dipped by DOT...well...you're in deep doo-doo.
For the 6.9's, if you still have the waper seperator in your system, it would be a good idea to drain it. Not sure if that will help, but it'll at least make you feel better.
For the 7.3's....well....I don't really know how their filter is setup. But apparently, the fuel filter and water sepeartor are the same thing on those. I don't know how they work, but I think I'd just replace the whole sha-bang and have good peace of mind.

Fuel system: Dependng on the age/mileage of your Injection Pump and Injectors...you may be due for replacement. The magic number seems to be about 100k miles. After that, the efficiency slowly tails off. Not that they just stop working, they don't...they just keep on going, but less efficiently. The $450 spent on a rebuilt IP may be worth the savings in fuel if you do a lot of driving. Injectors are very easy to replace, and they're so cheap, it's foolish to buy re-man's. I bought all 8 of mine brand new for $25 at my local fuel shop. Here: 6.9 Ford Diesel parts Fuel Injection Turbocharger
It's best to replace the IP and Injectors at the same time. An old IP won't put out the same pressure and will have a tough time "popping" the new injectors open for efficient injection and burning.
Think about it this way:
If you get 14 MPG with a worn out fuel system and drive 10k miles.
10,000/14 = 714 gallons of fuel burnt.
714 x $4.15 = $2,963
If you get 16 MPG with a fresh fuel system and drive 10k miles.
10,000/16 = 625 gallons of fuel burnt.
625 x $4.15 = $2,593
This 2 MPG increase could save you $400 in fuel costs. Only another $250 more and you break even with your fuel system investment.

Exhaust: Ditch that HORRIBLE, CRAPPY, RESTRICTIVE, USELESS Y-Pipe!!!! Really? A 420 C.I.D. Diesel engine has 2.25" exhaust off each manifold and dump into a single 2.25" pipe? That spells HORRIBLE. Not to mention the terrible angle of entrance from the passenger side manifold downpipe into the Y-Pipe. You can do this a few ways, but the end result is to open up the exhaust as much as possible. Diesel engines do not require ANY back-pressure like gassers do. So you can do anything you want really...
F250HDXLT had an exhaust shop make a sweeeet Y-Pipe for him. https://www.ford-trucks.com/forums/9...e-exhaust.html I plan to cut my Y-Pipe up by the manifold flange and weld on 2.25 to 2.5" adapter and then another 2.5" to 3" adapter and run a 3" elbow down until the transmission crossmember where I can adapt up to 4".
This thread gave me some ideas: https://www.ford-trucks.com/forums/5...l-headers.html

Intake: With an efficient exhaust path OUT of the engine, the idea is to gather as much air IN as possible! Some members have built ram-air setups that are just plain sweeeeeet! There are many links I will insert here when I edit this. Wreckinball has a sweet thread. VFelix has some awesome pictures also. Warozz did a ram air and reported either a 1 or 2 MPG increase (no mention in this thread though) https://www.ford-trucks.com/forums/9...an-shroud.html
https://www.ford-trucks.com/forums/8...-pictures.html
And wreckinball: https://www.ford-trucks.com/forums/1...od-v2-1-a.html
Oh, I forgot about cowl induction. Here's a link: https://www.ford-trucks.com/forums/9...induction.html

A/C: Obviously using the Air Conditioning can effect MPG's as it can rob a lot of power. I don't have A/C, so I have no experience on my own truck...but I know you can feel it kick on in other vehicles I've riden in.

Driving habit!!!!! This has got to be the most important, because my bone stock 6.9/T19 with no overdrive, and 3.55 gears when I was running as a dually got me 23 MPG on one tank when I drove ridiculously slow. The trick is to drive like there's an egg between your foot and the go-pedal. The slower you accelerate, the less fuel you use. It's as simple as that. If you floor it, you use a lot of fuel!
I can't seem to keep my foot out of the floor ever since I converted over to Single Rear Wheels. But here are my records:
https://www.ford-trucks.com/forums/g...vehicleid=6245

And other useful links here:
https://www.ford-trucks.com/forums/1...ge-thread.html
https://www.ford-trucks.com/forums/9...ing-25mpg.html
https://www.ford-trucks.com/forums/8...al-y-pipe.html
This is an INCREDIBLE thread: https://www.ford-trucks.com/forums/7...rs-thread.html

PLEASE ADD any useful info you know!!! I know there's a ton of things I have thought of the last couple days and I know I forgot some stuff!!

 

For the cost of doing all of those mods, you can buy a Toyota Corolla beater (preferably an 8 valve - it won't break), register it, wail the **** out of it daily and get 28+mpg. Park the truck and use only when used for its work function and 4WD in the winter. Diesel is at around $4.25/gal here. I have a 40 mile round trip commute.

 

Wow bud it would take me 2hours to type that! I know the a/c hurts my mileage but for a gut that is in short sleeves til its 35 degrees i likes me some COLD a/c. best i ever got with the c6 and 3.54's is 19.2mpg lowest empty is the day i bought it on a mix of 2year old no2 and winter blend 14.7mpg. usually average 16.5 to 18 depending on how hard i push the smoke switch. 2X on the injectors they got me an extra 1.5 on average.

 

The early mentioned stuff is all maintenance. Air filters, oil changes, fuel filters, tire PSI checks....stuff that should be checked and maintained anyways.
The fuel system was mentioned because if your system is old and worn out, you might end up spending more on fuel this summer traveling on vacations pulling the camper than if you had invested in a newer pump and injectors for that extra power and MPG's.
The intake isn;t expensive. I think I spent $15 on my parts. $10 for an 8' length of rigid aluminum 4" dryer vent tubing and a 4" range transition piece.
The exhaust is most important, and most expensive, but not terrible.
You could run a true dual 2.25" system and just buy 1 more muffler and call it good. Just run it until it clears the back of the cab. That would be much better than stock, and the cheapest way.
Later, you could clamp/weld on a 2.25 to 2.5" adapter and then a 2.5 to 3" adapter up near the manifold and run a nice 3" system for big power and MPG gains. But that would be more expensive, and would take a little longer for the fuel savings to pay for itself.
For those who use a pickup to commute to work, it may not be cost-effective. But I haven't yet seen a car for under $1,000 that doesn't need another $200 in repairs, plus registration, plus insurance. Here in MA, we have a yearly safety inspection, so the car/truck has to be in good shape to pass. And it's required to have it inspected within 7 days of purchase, so you have to repair the huge issues and slowly peck at the minor issues as time goes on.
For those of us who use our trucks for work every day, this list will be good to use as a check-up for the ol' money-maker

It did, it took me about 2 hours to type it and add the links as I surfed all over finding them lol

 

Well I like to get the best mpg I can out of my truck but I work at a toyota dealer and I agree that its just about easyer to buy a car ment for it. My dads 03 yota echo is getting 48 to 49 mpg on a regular bassist and it just a 1nz 4cylinder wit a 5 speed we have 4k in it has nothing wrong wit it

 

I think I know who helped give you the idea of this thread. HAHA

I have a 1.8L Sentra I drive when I don't need the truck. I get 30 MPG with mostly city driving if I grandma it. I can get more on the highway. I drive the truck a few times a week so it doesn't rot. I have a 4K mile trip coming up soon that I will need the truck for. No choice on that one. The Sentra can't pull a moving trailer.

BlueOvalbud, I would like to see some pictures or videos of someone doing the more intricate work you mentioned above. I can do routine maintenance but I have not repacked the bearings in an F250 before; same goes for the things you mentioned about the brakes. I think my brakes do need to be adjusted because I think they are rubbing. The PO put in new rear brakes and I doubt they adjusted them or lubed anything.

A/C is broken, so I won't be dealing with that unless I can find the leak (I expect the evaporator). I still gotta tackle that some more. The windows work, so I'm good for the most part.

I see a lot of people going with the U-haul IP and injectors. It seems like there are a lot of happy customers there. Is there any reason I shouldn't pick up a set from them? I think I can handle the installation of the pump and injectors but I will find a good diesel shop and have them time it with the right tools. Timing is everything, especially for MPG.

 

diesel went to 3.99 here...time to bust out the 1993 ford escort...wagon. oh yea, shes a race car.

 

That's right, MA does have an inspection. When I lived in VT & NH, I always brought my vehicles to someone we knew or a hometown garage to get an "inspection" and obtain a sticker. IIRC, it was $35 circa 1997. You could find an old 8 valve Corolla for $1500 which wouldn't need much more than an oil change and possibly brake pads. It would be a high miler, but will have a lower operating cost than daily driving an IDI.

That being said, your first post is very valid and I believe a lot of that would help improve fuel economy on these old trucks. I should really do a complete fluid flush on my transmission, transfer case and rear axle.

I've performed a cost analysis with a best case scenario with my IDI vs a moderate case with a cheap economy car. I'd be ahead by $728 as a minimum over one year driving the cheap economy car. The IDI's operating costs (fuel, oil, filters, typical maintenance items) outweigh those of a cheap economy car... significantly.

My truck needs tires. I was quoted $938 sans tax for off brand 10 ply tires. That's $85 more per tire than I was quoted 6 months ago. The tires were not factored into my analysis.

 

I just put new all-terrains on my truck last month (no more mud tires) at 60 psi, and I have a rebuilt IP and injectors waiting to go on hopefully soon. I'm getting 13 mpg at best, I need that mpg boost that's for sure.

Also- if I had a 30 or 40 mile commute, or hell anything over 10 miles, I can guarantee you I would not be driving my truck. I couldn't afford it!

 

don't forget the axle fluid changing out that old 80-90w can help mpg as it reduces rolling resistance.

i changed oil, antifreeze, trans, rear end. front diff and noticed an improvement in mpg

the maintenance cost is pretty high compared to a 4 cyl but if you need a truck it is defiantly cheaper than a stroke to maintain

 

swap out the stock energy hog engine fan for some oem twin e-fans.
(pre-93/serp belt; 3g alt upgrade required first.)

 

I had a couple more things I thougth of today while working. Man, if only I could remember them all!

Injection Pump Timing is a big one. I'll edit some links here in a bit as I find them.

The 4x4 crowd who are running larger tires. Those big hogs will take a bit of power to spin them, but if you can develop a responsible driving habit with those meats, then you could actually gain the advantage of overdrive with them. The larger diameter tires means your effective ratio will be higher than your actual ring and pinion. Use those big tires to your advantage if possible!

K&N air filters can be a touchy subject, but I have one and truly believe in them. The amount of more air in the engine in my '65 F350 was incredible. My "Butt Dyno" reported a good 5-10 horsepower increase over the stock oil bath air cleaner. The trick to a K&N is keeping them clean and oiled. They're meant to be washed/cleaned, allowed to air dry, and then oiled with the special K&N oil that comes in the cleaning kits. I can't wait to pick up Snapon's used K&N in a few weeks That in combination with a 3" true dual exhaust and dual ram air intakes should make for an excellent N/A engine.

 

The maintenance tasks mentioned earlier are covered very well in the averge Chilton or Haynes repair manual...much better than I will be able to type out...but I'll give it a shot and give the simplified version

Packing wheel bearings is a simple task. Let's aim our focus on a 2wd front wheel bearing. Begin by breaking the lug nuts loose, then jacking up the truck, and then pulling the wheel off. Begin by removing the brake caliper. I don't even know for sure what year the sliding dual-piston calipers were used, but my 85 2wd has them and I LOVE them. Remove the 1 bolt at the bottom of the caliper, then use a hammer and a drift or chisel and drive the "T" out from betweent he caliper and caliper bracket. Once the caliper is free, don't let it hang by the brake hose!!! Rest it on an upside down 5-gallon bucket or see about trying to prop it on the radius arm or frame rail.



Then use a screwdriver or prybar to pry the dust cap off.



Now you can remove the cotter pin and take the spindle nut off. At this point, you can actually grab the whole hub and pull it right off the spindle. But, it would be good if you pulled it off about halfway, then push it back ont he spindle. This pulls the steel plate/washer and the outer bearing out to the end of the spindle where you can easily grab it and pull it off without much mess. Set your bearing down on a clean surface with no dirt or debris. I use a paper plate.
You should be right about here:



Of course, yours will be covered in grease. I already wiped mine down with a rag and brake parts cleaner for the picture, just prior to assembly. To access the inner bearing, you'll need to pry the rear wheel seal from the hub. Use a flat screwdriver and rip it right out. You'll replace it with a new one anyways.



With the seal out of the way, pull the inner bearing out. Now is the time to inspect the bearing and see if it's worth your time to re-pack it or purchase new bearings. Timken is the BEST bearing you can get. To test your bearing, use your best judgement and see if there are any deep scores, excessively loose roller bearings, or anything that may just seem weird. If it looks good, then proceed. Now is also the time to inspect the bearing race for any scoring also.
Grab a small pail or bucket and fill it up about 2" deep with gasoline. Put your bearing in the gasoline and flush it out. Get it good and clean, just in case your new grease doesn't mix with the "who knows how old" grease. (usually I let the bearing soak while I work on the other side) Use your fingers to move the roller bearings around real good and get it as clean as possible. Flush it around in the gas if you have to. When it's nice and clean, allow it to air dry.
With a nice fresh bearing in one hand, use your other hand to take a good amount of wheel bearing grease from the tub and then "pack" the bearing. The idea is to FILL the bearing with as much grease as you can get in. Press it inbetween the rollers, anywhere you can push it. It usually takes me about 10 minutes or so to really pack it good. Of course, you can always get a "Bearing Packer" at an auto parts store or tool store. Sears: Online department store featuring appliances, tools, fitness equipment and more
Once your bearing is good and packed, it's time to re-install it in the hub. Just drop it right into the race. Then add some grease around the edges of your seal and gently tap/drive it in the hub with a hammer. Now your hub is all set for install.
Grab a rag and wipe your spindle down clean. I use old rags to get the most of the grease, then use fresh rags and brake parts cleaner to get the spindle as clean as possible. This is what my spindles look like before I grease them.



Now grab your grease again and smother the spindle with grease. Don't be shy, remember...your wheels are spinning VERY fast on the highway and ride on this spindle. Give extra attention to the back of the spindle where the new seal will "seat" on the spindle. You'll want to clean that area VERY well and be sure it's greased well to have a good surface for the seal to ride on. Remember, the wheel seal is attached to the wheel hub...which is rotating at all times the tires are moving. The seal will be spinning on this surface, be sure it's in good shape!
With the spindle all greased up, install your wheel hub back on the spindle. Now, you can clean and pack your outer bearing. Once it's packed, push the wheel hub back on the spindle all the way and push the outer bearing into the hub. Take your fingers and push as much grease as you can into the void between the bearing. Remember, where grease is...water isn't!
Clean up that steel plate/washer and install that. Clean up your spindle nut and install it. I've never torqued mine, I just use my experience to tighten it down, then back it off just a touch to a point where the wheel will spin freely, but is still tight. Install your cotter pin. Apply more grease to the spindle threads just in case you get water in there. Then put your dust cap back on. If it doesn't fit tight, I've used multi-purpose glue to hold mine on. 1 year later, they're still on there.

Now you can install your calipers again. Use a rag and brake parts cleaner to clean off the caliper bracket on the top and bottom where the calipers "slides". Apply some grease to these sliding areas for the caliper to easily slide. This is important for the caliper to slide, so that your brakes release and don't get hung up.

Here's how the caliper hardware works in case you forgot, or if they came flying off LOL Been there, done that!!




Here's my thread in my swap from DRW to SRW: https://www.ford-trucks.com/forums/9...surements.html
Here's my album of DRW to SRW pictures: Ford Truck Enthusiasts Forums - BlueOvalBud's Album: 1985 F350 DRW to SRW Swap

And all my albums, for any kind of technical things you may need a picture of...I might have it. Ford Truck Enthusiasts Forums - BlueOvalBud's Albums

 

I spent 1.5 hours on the bearing section tonight, I'm beat. I'll do the rear brakes and some other stuff tomorrow.
A lot of folks hopped on the U-Haul sale, and have reported positive results. Myself, I'm a bit old school and don't buy anything I don't touch or test before the sale...so i deal directly with my local fuel shop and gladly pay more. Sounds funny, but I'm in business with my equipment and need parts NOW if something fails. Having a good relationship with local shops is crucial to keeping downtime to a minimum

I agree, a small 4-banger will certainly cost less. However, in my experience, a cheap car typically nickle-and-dimes you dealing with someone elses headache. By the time you go thru the brakes, bearings, fuel filters, air filters, and an oil change...and purchase the car, register it, and insure it...that's money you could have put toward the single vehicle you already have. And now, you're faced with the decision of either taking your pickup off the road (and now losing a back-up car if the new beater dies), or you're still going to be paying for the truck insurance and registration while it sits in the driveway.
It depends on how long your commute is I suppose


13 is very low for a truck with overdrive. I can pull 16 average without overdrive, with 3.55 gears. See what those fresh injectors and IP do for ya

 

your currently at 13.20 MPG average @ 28 tanks actually.

Ford Truck Enthusiasts Forums - Garage Fuel Economy

however it could be said;you have "peaked" 16+ mpg's before.
i feel this difference is important for people to understand,so others don't get discouraged in their quest for improved economy.