Big Diesel, MPG increase ideas?

[ps2fixer]

Yea that 90 Lexus rotor design is simple but effective. I've read ford used a 4x4 transmission on a 2wd truck to attach a drum to it and have a parking brake for their first 4 wheel disc brake trucks (like F350/450 size). Never seen a pic of one though to validate.

Personally, I'd rather have the drum brakes in the back, but the disc setup is easy to upgrade. The 90 LS400's came with weak brakes from the factory, the 93-94's got ~1in larger rotors and swap the bracket/caliper and it's a bolt on swap. 95+ can be swapped for even better brakes, I think they have 4 piston calipers, but it requires the tie rod ends being replaced to the new style to clear and larger rims. Every vehicle I've had before where always rear drum, front disc. It's so weird moving the pedal so far down before the brakes come online, feels like the rear brakes need adjusting, but there is no adjusting to do. The ford has that problem, but haven't pulled the rear drums yet to inspect the wear and adjust them up. My T100 applies the brakes right away, but I adjusted the brakes up in the back after I got it.

Anyway, I'd say 100% my sister is more country than a typical city girl. She shows interest in some things but it's fairly limited. She didn't grow up on a farm so wasn't really made to do physical labor. On the other hand, I grew up in the same house but the situation was different. Basically I had to entertain myself and generally that meant I was kicked outside to do something "constructive". By around 12 I dug through the scrap pile and started messing around with lawn mower engines, later got into electronics. After college I've done a lot of "online research" on topics of interest, that's how I got into this site. Anyway, my sister does pretty well, I'd like to see her do a bit more, but I can't expect her to want to work on cars etc. She likes graphic design and photography and she has a better eye for that kind of stuff than me. I can do just about anything on a computer except graphics. Ironically she wanted to learn basic programming back when I lived there, that lasted for about 2 sessions lol.

I think once the weather warms up and she gets more hours behind the wheel, she might be more open to driving a manual. She has drove a quad for years, however it's fully automatic lol.

[cRiPpLe_rOoStEr]

Originally Posted by ps2fixer

I've read ford used a 4x4 transmission on a 2wd truck to attach a drum to it and have a parking brake for their first 4 wheel disc brake trucks (like F350/450 size).

I remember some Japanese vehicles, such as Toyota J40 and more recently some Isuzu N-Series trucks, had a parking brake drum attached to the transmission even while resorting to drum brakes all around.

Every vehicle I've had before where always rear drum, front disc. It's so weird moving the pedal so far down before the brakes come online, feels like the rear brakes need adjusting, but there is no adjusting to do. The ford has that problem, but haven't pulled the rear drums yet to inspect the wear and adjust them up. My T100 applies the brakes right away, but I adjusted the brakes up in the back after I got it.

Most vehicles I drove were front disc, rear drum. On a sidenote, I remember one day a friend complained about the front disc brakes of a car his sister owned at the time to be so weak it felt like drums all-around. People usually consider drums to be outdated, but they're still widely used on commercial vehicles in countries like mine (Brazil) because some operators consider them more reliable under harsh environmental conditions, plus IIRC nowadays most are self-adjusting.

Anyway, my sister does pretty well, I'd like to see her do a bit more, but I can't expect her to want to work on cars etc.

As long as she get to know how to change a flat tire instead of bossing some random guy to do it, she will be better than the majority of "modern" women who either call their insurance or believe they're entitled to have any random guy to do it for them out of "gentlemanliness". It had been quite bothersome to deal with old ladies who interrupted me while I walked the dog around as if I had some sort of obligation to change a flat tire.

[ps2fixer]

I haven't quite had that kind of experience with women up here, but I'm not normally walking around much either, just walking in/out of stores to my vehicle to drive to the next spot lol. I'm around the start of the so called millennial generation. I connect so little with people my age though. That whole entitlement thing is their major downfall. I'd like to think I'm not like that, but I know I'm not quite the same as my dad's generation either. I know his worth ethics are stronger than mine, but I atleast put forth effort to make things happen. Kind of reminds me when I was younger, I hand shoveled a lot of dirt to basically help make my dad's back yard not a swamp. He had a tractor that whole time but no front end loader, but had a welder and plenty of metal to home build one. I guess I didn't think far enough ahead to even suggest the idea. I'm sure I shoveled atleast 150 yards of sand. The swamp used to come right up to the house just about, now it's beyond the pole barn which is 50+ feet long. My dad has a backhoe so that's why I'm looking to get a skid steer. No point in having the same machinery as everyone else and the skid steer should move dirt etc a lot faster than a backhoe and tons faster than hand shoveling xD. Even though it wasn't an efficient use of my time, it kept me busy and out of trouble and probably grew up with less bad habits because of things like that (no smoking, drinking, drugs, etc). I was using energy drinks for a while, quit those, used to drink pop like it was water, quit that too. About the only thing I have a bad habit of is I like sugary stuff yet, but I've been buying less of that kind of stuff. The pop thing is weird, I don't even really think about it when I don't have it, but if I have it, it's like every time I go for a drink, pop is #1 pick, so I just quit buying it and problem solved.

Anyway, back on the truck. I swapped out the multi function switch (blinkers, dim/bright switch, washer fluid) because it has a couple functions not working, well the replacement from the parts truck does the same thing. The functions worked fine on the parts truck, so the switch is likely good. There's some wire hack job work going on, not super terrible work quality, but clearly not done right. I recently bought access to Ford wire diagrams, so if anyone has a Ford and needs a diagram, shoot me a message before the subscription runs out (only 3 days and I'm on day 2 I think).

I don't think I mentioned it, but the fuel filter housing's drain valve has a small weep leak, I read there's 4 o rings in there. Guessing they are probably from when the truck was built. Front axle is a bit wet at the pinion area, could be the fuel leaking down the back of the block but not 100% sure.

For the grill block, I'm thinking of making a home made one. Make it similar to the ones that can be opened up for summer time, but maybe I can make it cover the whole front end with cut outs for the lights to actually seal up the front end fairly well. At the same time, could just focus mainly on the grill. Currently using cardboard, but ideally I'd have a grill cover so if it needs to cool the fan can pull air though the radiator yet.

Also, on my Toyota I saw no gain removing the clutch fan. My dad's been running his (same truck again lol) for years. He recently ran the truck for a while and got it hot, just enough to boil but not cause any damage. The diesel's fan is stupid heavy, I don't quite understand why the cooling fan needs to weigh like 50lbs. The fins are like 3/8in steel and the main frame the fins attach to are like 1/4in. With that much mass spinning, I suspect there could be some gains there. Either swap to electric, or maybe mount a lighter fan like from the Toyota trucks. Of course the toyota one is deisnged for a higher rpm engine, so might not pull enough air. Not really a big focus atm, but something to ponder on.

I haven't researched much on how the vacuum pump works, but in theory it shouldn't need to be running continuously, only when heater controls change, or the brakes are used. I suspect an electric one that automatically cycles could be good to lower the accessory load on the engine. The newer version of the truck uses a hydro boost setup for the brakes and all the heater controls are electronic controlled so no more vacuum pump for 99+. I've read a few times removing the accessory belt is good for about 10% better mpg, but with an engine of this size, I'd guess that figure would be a bit less. Of course the batteries have a large load on them and the alternator has quite a job to recharge them back up so after the initial start there's probably a lot more than 10% to be saved. Not willing to do an alternator delete due to the nature of these diesels needing a lot of power to start up.

Sounds like throwing a tune in the engine should give a solid benefit to mpg. From what I've read, the timing is advanced a bit and promotes more complete combustion. If I did anything with the WMO, it burns a lot better with advanced timing according to posts I've read. I guess WMO has a slower flame front than diesel.

Oh, I don't think I reported on the block heater situation. I bought a new cord for it, pulled the old one off and one of the terminals is loose so the block heater is also junk. I guess I should have checked that first, new block heater comes with a cord.

[wjohn]

Originally Posted by ps2fixer

I found suggested shift points for the diesel in the owner's manual (diesel supplement), wow I was really over reving it according to their figures. I was shifting into 5th at around 50mph, all the other shifts were based on rpm @2k. I'll have to see what kind of rpm the shifts are at. Same book also suggests idling for 5-7 mins after a long trip to cool the engine, but only 15 seconds after starting a cold engine before taking off. It basically says to wait for oil pressure to rise to normal range. The book doesn't say what year it's for, but clearly it's for a 99+ truck. Looked at the axle ratios in the book, it doesn't even list a 3.55 as an option. I guess I got the highest gearing possible for a factory f250 with the diesel.

EDIT:

Took the truck for a quick drive (still warm from doing some work on it and keeping the batteries topped off). Every gear shift suggested in the manual for best mpg is around 1500rpm, 2nd into 3rd is around 1900rpm (bigger jump in gearing). I'll have to target the 1500rpm shift and ~2000 rpm shift for 2nd into 3rd to see if I get good results. The truck seems fairly happy with those shift points, I think when I was testing before the shift I watched the most was 2nd into 3rd which is the big jump and 1500 is too low for that shift.

A little late with my response here but I was going to mention I shift at 1500-1800 RPM (generally higher RPM to jump between the higher gears) with my Cummins-powered Ram when unloaded. That's about what I shift my '90 Civic at, too, so I didn't have a hard time adjusting. My Dakota has no tach but I can tell I rev it higher between shifts... Although it's pretty worn out.

Anything over 2000 RPM in the Cummins sounds like screaming to me by now, so when I tow (not often lately) I have to remember to force myself to leave it in gear a little longer.

[ps2fixer]

Yea I think the ~1500 or so rpm is a pretty good shift point on a diesel as long as the transmission is geared for it. The 2nd to 3rd shift is a massive one, if I shift at 1500rpm, it drops to like 800-900 rpm vs other gears around 1000-1100rpm.

My last tank fill up wasn't great, about 16mpg. The whole tank was short trips, no block heater, and every start was cold with 2 glow plugs bad so idle time to warm up etc. Not terrible, but clearly the block heater will save a ton of fuel. I haven't drove the truck for a while since it's at my dad's. He put the block heater in and I think he was planning to throw the other bank of glow plugs in. I bought antifreeze to replenish what came out, and engine oil to do a change since I don't know when it was last changed.

On a side note, I've been driving the Lexus, and it's been super cold here that the mpg has dropped tons for it too. It's around 15mpg for the last fill up, it normally runs around 18-20ish with no mods.

I haven't really worked on the truck, I don't do too well working outside in the extreme cold (15F and lower). I did pick up some parts vehicles to part out/scrap from a neighbor though, so that forced me out in the weather a little.

[cRiPpLe_rOoStEr]

Originally Posted by ps2fixer

Either swap to electric, or maybe mount a lighter fan like from the Toyota trucks. Of course the toyota one is deisnged for a higher rpm engine, so might not pull enough air.

I'd rather pick an electric fan, as it would lead to a more accurate temperature control. When it comes to a mechanical fan meant for a smaller and more rev-happy engine, a different pulley ratio may be the key to deal with this issue if you decide to not get an electric fan.

[Piotrsko]

With 8 gallon of coolant, you can probably get by without the fan under light load definitely could lose the clutch and run a flex fan Mine only engages pulling a 6% hill on a warm day otherwise the fan clutch is slipping. You'll hear it when it engages, even inside with the A/C on.

The 7.3 is supposed to only burn 1/3 QUART of fuel an hour at idle so theoretical 120 hours on a full tank

[ps2fixer]

The cooling fan shouldn't be used if you're moving more than like 35mph, there should be a LOT more air being forced through the radiator than what the fan could ever pull. From my understanding, the fan is only for slow speeds, and while stopped. On my corolla, it never kicked on the fan, when I got the car the fuse was blown for it. Idling for like 45 min one day for an engine oil treatment (system 48), it hit a peak temp of around 270f according to the scan gauge. That's the day I found the fan didn't work lol. Ironically, the overflow wasn't boiling, not sure how that's possible unless the radiator cap was stuck shut and the system was under a lot higher pressure than designed.


1/3 quart of fuel per hour is crazy low, that's 12hr on one gal (3hr per qt, 4 qts for a gal), my 1.8L corolla was around 3hr for one gal. I'm guessing the figure is 1/3 gal per hour based on your 120hr for a tank (40 gals)? If it's the 1/3 qt rating, then I really need to get one of these engines setup to be a generator, 2 gals for a day isn't bad for idle, clearly generating power would take more fuel.

With the 8 gal of coolant, it takes a long distance to hit full operating temps. When I drive to town it hits them, but that's a 25-30 min trip. When I go to something locally around me, it's around a 10 min trip and it hits something like 140F for the oil temp. I don't have a working reading on the engine temp yet. Every truck I connect to with this engine reports -40F lol.

[Isaac Zachary]

Originally Posted by ps2fixer

The cooling fan shouldn't be used if you're moving more than like 35mph, there should be a LOT more air being forced through the radiator than what the fan could ever pull.

Wrong. Fans need to pull in way more air than what gets forced through the front. Even at speeds of 50-60mph or perhaps even more, the air that's naturally flowing in through the front may not be enough.

For an example, on long hill climbs at highway speeds the fan will kick in and suck in way more air than what's forced in by moving through the air. At least this has been my experience in several vehicles. I had the fan motor fuse blow once in one of my cars going up hill at 50mph. The engine began to overheat, and it was only about 50°F outside. I found what blew the fuse (a screw in the cigarette lighter) and replaced the fuse and things went back to normal for the rest of the climb.

[ps2fixer]

That doesn't match my experience driving with no cooling fan at all. Ideling will overheat the engine, moving slowly like 15-25mph it stabilizes fairly well, and 35mph+ it cools and never gets any hotter than with the fan. I'd dare to say you have a dirty radiator, restricted coolant flow, or the vehicle is of a poor design.

Ages ago I remember some nascar driver saying they only need a radiator the size of a beer can to cool the engine while driving on the raceway. No stop and go traffic there.

My oldsmobile cutlass ciera was the same way too, I could hit the fan kick on because it was so out of balance. It also had the fuse blown when I got it, found out the fan didn't work when tuning the sound system (balancing the base and such) with the engine running. Every time I stopped for about 2 mins the cooling fan would kick on, but never while moving.

Of course there's always exceptions, like a rear engine vehicle I'm sure the cooling fan is 100% required since it doesn't have the frontal area.

If I did the math right, it's about 4840 CFM per sq ft of radiator at 55mph.

A quick search suggests this is one of the highest rated CFM fans for 16in (over 1 sq ft area) and it only pulls 3140 CFM. The radiator in every vehicle I've ever owned has been a lot larger than 1 sq ft, smallest I've seen is a geo metro and I'd guess it's like 1.5 sq ft.

https://www.becool.com/jump/fans

Assuming the fan is 16x16 square area, it's 1.78 sq ft. Same area with 55mph air would be 8615cfm. If I did the math correctly, the fan's ability to move air vs the natural air speed of traveling are roughly the same at 20mph.

Here's the source for the math I used, I reversed what they did since I'm starting with mph.

https://sciencing.com/how-8191327-ca...e-cfm-mph.html

It's very possible I got the math wrong, but I suspect it should be pretty close since that matches up with my experience. Of course the CFM of driving through the air will be a little less because of the air resistance through the radiator and it's not 100% exposed. even at 50% or the air going through the radiator, it would be 40mph+ a cooling fan can't keep up.