7.3L Power Stroke Engine and DrivetrainDiscussion of the 7.3L Power Stroke diesel engine and drivetrain in the 1999-Up Super Duty trucks and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 7.3L Power Stroke engine.
ok now i know people have throw this idea around used motor oil as a fuel now this isnt far fetched if its filtered throw a micron filter one or two times that should remove any contaminats know i have seen diesel motors run on almost anything even suck there own oil into the cyclinders and run and thos same motors are still running know i also know that my 02 spd 7.3 is not the the same but has anyone tried this or someone that has. Now my next question is this i have an automatic F250 4x4 super cab long box 7.3 315/75/16 tires and at 70mph my rpms are at 2500 know is that nomarl? i dont know the gears any help would be awsome thanx
Not familiar with the waste oil. But the gears I have some info on. If your truck came stock with 3.73:1 gears, then the following will apply: 4.11:1 will return you to stock if you're running 35's (315/75R16), and 4.30:1 will return you to stock if you're running 37's. If you type in "Gear Ratio Calculator" on google, you can select from a few calculators (rocky-road.com, & compushift.com are a couple of many). You will need to know your current gear ratio & stock tire size, as well as your current tire size. A lot of F250 SD 4X4 trucks have the 3.73 gears. The mathematical conversion will be slightly different than what is available in gear sets. I'm runnin' 4.30:1 gears with 37" tall tires. Stock was 3.73:1 with 32" tires. The math came out to 4.27:1, so 4.30's were the closest. That put me within 20+/-RPM of stock. Truck drives awesome after the regear. Good Luck
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2003 F250 XLT 7.3L, Auto, FX4, Crew Cab, Long Bed, 6.5" Pro-Comp all spring lift & Firestone HD Rear Air Bags, BFG KM2 37x12.50x17 tires on Eagle 17x10 Rims, 4" Turbo Back Exhaust & muffler delete, Bully Dog Programmer @ 120 Hp setting ALWAYS, Autometer Overhead Gauges (Boost, Pyrometer, Trans. Temp), Custom Pre-Filter Ram-Air with K&N filter, Custom 20,000 lb working capacity HD Trans. with 3 Disk Billet Torq-Converter, Redline Racing Clutch pak, Kevlar Band, Hughes Racing Valve Body, Kryo-3M 3,000 ft/lb Input Shaft, Hughes Racing Deep Structural Pan, and a few more goodies. Now spinnin' AAM Rear & Dana Spicer Front 4.30:1 Gears with Warn Premium Locking Hubs.......I do a lot of towing.(13,000 lb 33' Toyhauler & 21' Ski Boat).
I can tell you some about the oil. I burn all of my waste oil in my truck. There is a local guy near me who owns an oil change place who says he burns up to 70% waste oil. He only gets it from him regular customers and filters it first. Above 70% it will smoke more. I run less than 25% most of the time. You see no difference in performance, except from your dollars for oil. Like most things moderation seems like the way to go. The motor is treated like a garbage disposal by some, it can burn anything from oil (vegi or dino) to chicken fat. I want to keep mine on the road as long as possible hense the conservative route.
Good luck.
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2001 4X4 Excursion LTD 7.3PSD. Gets the job done and is still family friendly.
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2003 F250 XLT 7.3L, Auto, FX4, Crew Cab, Long Bed, 6.5" Pro-Comp all spring lift & Firestone HD Rear Air Bags, BFG KM2 37x12.50x17 tires on Eagle 17x10 Rims, 4" Turbo Back Exhaust & muffler delete, Bully Dog Programmer @ 120 Hp setting ALWAYS, Autometer Overhead Gauges (Boost, Pyrometer, Trans. Temp), Custom Pre-Filter Ram-Air with K&N filter, Custom 20,000 lb working capacity HD Trans. with 3 Disk Billet Torq-Converter, Redline Racing Clutch pak, Kevlar Band, Hughes Racing Valve Body, Kryo-3M 3,000 ft/lb Input Shaft, Hughes Racing Deep Structural Pan, and a few more goodies. Now spinnin' AAM Rear & Dana Spicer Front 4.30:1 Gears with Warn Premium Locking Hubs.......I do a lot of towing.(13,000 lb 33' Toyhauler & 21' Ski Boat).
I have been burning wmo for about 60,000 miles now in my 03 6.0 no problem but I do centrifuge very well first. 70% oil to 30% diesel.I prefer trans fluid but noone wants to give it away.
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03 f-250 6.0 custom tunes sct
2 trips to the dealer ship to fix the same problem
got tired of wasted trips
fixed it my self ARP headstuds, EGR blockoff plate and guess what (no more problem !!!)
all work done by me
Now my next question is this i have an automatic F250 4x4 super cab long box 7.3 315/75/16 tires and at 70mph my rpms are at 2500 know is that nomarl? i dont know the gears any help would be awsome thanx
If you posted in the right forum, your truck came with 3.73 rear axle ratio, and with stock-size tires the speedo would show 70 MPH at 2,000 RPM. With the 315 tires, it would feel like a 3.42 ratio. 70 MPH would be about 1850 RPM.
So if your tachometer shows 2,500 RPM at 70 MPH in overdrive with 35" tires, then you have some really short gears - around 4.88 or maybe even 5.13. That sounds like it was probably set up for a rock crawler or else for much taller tires than your 35s.
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My Sierra Blanca is a '99.5 PSD CrewCab hot-rod Towing Machine! BTS tranny; TurboRamAir intake and 4" stainless turbo-back exhaust; DP-Tuner tunes flashed into an Edge Evolution tuner; ISSPRO EV gauges and TTM; AIC; SP-Diesel exhaust brake and torque converter controller. I special-ordered it new and plan to drive it until it quits.
not to get off topic but what are you guys using to filter the WMO?? also are you all using motor oil designed for gas enigine or will any motor oil work???
not to get off topic but what are you guys using to filter the WMO?? also are you all using motor oil designed for gas enigine or will any motor oil work???
5-10 micron GE whole house water filter from home depot, and then into a 2 micron oil/water separator from Summit Racing.
Any oil will work, though some say synthetic won't.
Smokey, quick question. If he is running 2500 rpm with 35 inch tires, and he has the oem 3.73 rearend, wouldn't the higher rpm be indicative of a slipping torque converter, or that he isn't in OD? I run stock tire size and a 3.73 ls, and I've noticed that my tachometer is slowly creeping up to between 2050 and 2100 rpm at a sustained 70 mph on flat, level ground with no headwind, running empty and not towing anything. If I drop the speed down to around 67, the rpm's drop to right at 2000. After spending the last 9 years reading about our trucks here, I've gotten somewhat paranoid looking for the tell-tale signs of dooming failure (transmission, the dreaded uvc, water pump. just curious.
short_stuff
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Y2K F250 CC PSD Auto, Short-bed Lariat, Woodland Green/Gold, ordered 07/10/99, born 09/12/99, delivered 10/08/99, Access bed cover, Bed Rug, Zoodad mod, Viper Remote Start Alarm, Fumoto valve, 103K somewhat error-free miles (so far) [never back to dealer for anything]
Repairs: CPS, Water Separator Valve assembly, rear axle bearings, VSS, batteries, brakes, alternator, serpentine belt (x2), driver door pwrlock actuator, water pump
2003 VW Jetta TDI auto, 90k miles, all stock, no mods, 41 mpg most days. A rocket in disguise...
Repairs: alternator, brake switch (x2), power window wire harness, #4 glow plug, glow plug wire harness
On order - 2009 VW Tiguan (2.0 l turbo gas engine to take advantage of $1.79 fuel prices [for now])- should arrive off the boat soon.
If he is running 2500 rpm with 35 inch tires, and he has the oem 3.73 rearend, wouldn't the higher rpm be indicative of a slipping torque converter, or that he isn't in OD?
Not in overdrive should be about 2,400 RPM with 3.73 gears and 35" tires. And if he does have it in overdrive but a torque converter is slipping that much (about 29 percent), it's short for this world.
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I run stock tire size and a 3.73 ls, and I've noticed that my tachometer is slowly creeping up to between 2050 and 2100 rpm at a sustained 70 mph on flat, level ground with no headwind, running empty and not towing anything.
With a speedo calibrated so the odo is 99+ percent accurate, 3.73 ratio, and stock size LT235/85R16 or LT265/75R16 tires, the speedo should show very close to 2,000 RPM at 70 MPH. Mine does.
If either the tranny or torque converter were slipping enough to cause the speedo to be 3 MPH slow, the tranny should overheat in a heartbeat unless the tranny coolers are doing one heck of a great job.
Wow thanx's to every one that replyed to my problem, now i tested this out just took a trip down south, cruse set at 70mph and whatching the tach to see if it went through all the gears it did, now to the whole in OD or not i check this if i shut it off the rpms jumped to 2450 or so just under 2500 and when reengaged it droped to 2250 or so my spd only has 62,000 on it but i noticed that driving around town my truck took a longer time to get in to OD could this be my trany? my main thing is this i get like 17.5 mph around town (this is an avarage over 10 full tanks broken down in to quaters) so when i get on the freeway i get like 12-13 mpg and like 10 towing 10,000lbs my math is right than i get worse high way mph that goes against all nomalsy and for the wmo is fine to run as long as its filltered well thats great case that makes my wallet happy with a 38gal tank thanx again for all your help guys
Under valve cover (UVC) wiring harness. The wires that go to the injectors to control when the injectors fire. That wiring harness has been a problem area on 7.3Ls. The fix is simple each time, but then it might happen again next week. The DTC (diagnostic trouble codes) tells you which cylinder, so you remove the valve cover for that cylinder and replace a clip that holds the wiring harness. Then bolt it back together.
It's only happened to me once in 9 years and 174,000 miles, so it doesn't happen every day. But our 7.3L trucks are getting long in the tooth, so things are slowly going to pot.
So. Cal. Fireman 
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