Best fuel mileage, and reliability pickup diesel?

Hello Badger,

Try

for GM diesel info. They also have a discussion forum with very helpful members.

Franko

98 Tahoe 6.5TD 4x4, 160k miles (22mpg highway/16 local) 86 Suburban 6.2 NA 2WD, 165k miles (26 mpg highway/18 local)

I'm going to chime in with my personal opinion, just so long as you recognize that it's just an opinion and not the gospel truth.

I think your list should read as follows, based on what experience I have with my own trucks, trucks at work, and friend's trucks.

For diesel pick-ups with 150K+ miles/7-10 yrs old:

Dodge (I-6 5.9L Cummins Turbo Diesel, Intercooled, direct injection): Best motor, best mileage, poor automatic transmission, good manual tranny. Ford (V-8 7.3L Powerstroke turbo diesel, intercooled, direct injection): OK motor, worst mileage, poor automatic tranny, Unk manual tranny. Chevy (V-8 6.5L turbo diesel, non-intercooled, indirect injection): Motor OK but not powerful (better after '97), middle of the road mileage, best auto tranny, Unk manual tranny.

My friend still gets 23-24mpg on his 1989 Dodge with a manual tranny. I used to get 20 mpg on my '95 Chevy 6.5L turbo diesel with the automatic, and trucks at work (when we used to use Fords) got 13-14mpg at best with the automatic tranny.

I hated the Ford E4OD automatic transmissions, and I heard the Dodge automatics weren't much better. Funny how all the folks I know with Dodge trucks of that generation all had sticks - something to do with the automatic not being able to handle the torque of the Cummins 5.9L motor. Chevy always had the best tranny's but the 6.5L wasn't the motor you wanted if you wanted to pull, plus you had to really want to learn about them to keep it running reliably (the Fuel Solenoid Driver was issue #1).

My preference based on the criteria you list would be one I didn't even list - a 3-4 year old Chevy or GMC 3/4-ton with the Duramax 6.6L turbo diesel and the Allison 1000 tranny (I have a 2004). Good mileage (20-21), good reliabilty, and a great transmission. Just make sure it has a 3.73:1 rear axle for the highway.

My two cents worth - Jonathan

What year range are you looking for? what about price range? I have seen reports of gues with the old 12V and 24V (pre1991-1998 range) Cummins Diesel trucks getting 20+ MPG. A friend of mine had a '99 Ford Excursion 4x4 Diesel, he got about 16 MPG. With the new Cummins 600, many have said the fuel economy has gone down (mainly due to such high power output) if your not pulling anything, and if you dont care about the noise, then then the

12v or older 24v would be great, (if the trans will keep up) As for Chevy, a lot of guy I have talked to said dont get a pre-Duramax. The Duramax was built in collaboration with Isuzu, (whom have been making Diesels for many years) So the engine is pretty solid (even with aluminum heads) and then the Alison trans is pretty much the way to go when it comes to transmissions. I think the Duramax gets around 15-16 as well. I have heard a lot of mixed reviews about the new Ford 6.6 Liter Diesel. their old 7.4 was a pretty solid machine as I recal. just not the most fuel friendly since its a 7.4, where the Duramax is 6.6 and the Cummins is 5.9. So just in those terms, the Cummins has less displacement, and does not consume as much fuel at any given RPM (if all three engines were mapped to use the same amount of fuel per liter)

What speed will you be traveling at most? 5mph? 30, 60 85? If your sitting in slow traffic, I would think the Cummins would be better since it would be in a lower gear at a lower RPM. but if your traveling at 60-80, Chevy has a five speed trans, where Dodge has four. So the Dodge my run at a higher RPM at freeway speeds. The two trucks may be geared differently to accomodate the difference in transmissions though. If your doing a lot of empty driving, I would go with a 3.55 or higher rear end.

BTW, I am 01 few that do understand Binary.

Just for a clarification, the new Ford Powerstroke is a V-8 6.0L (not 6.6L) turbo diesel with direct injection and an intercooler. The new tranny is also a 5-speed similar to the Allison (but Allison is the King of the Hill). The older 7.3L motors had only 2 valves per cylinder which is one reason why they weren't that efficient. The new 6.0's use aluminum in their construction similar to the Duramax, and use a variable vane turbo.

Chevy/GMC uses the Isuzu-designed Duramax V-8 6.6L turbo diesel with direct injection, pilot injection, and an intercooler. The current Allison tranny is a 5-speed, with a 6-speed automatic with selectable fully automatic or manual shifting in 2006. This is currently the largest motor of the Big Three. The latest version (LBY) uses a variable orifice turbocharger. I've heard rumors that current 5-speed Allison's are upgradeable to 6-speeds with only a computer update, although they won't have the selectable automatic/manual shifting (6th gear being a double-overdrive).

All three manufacturers currently use 4-valves per cylinder, although most were typically 2 valves per cylinder in the older models. Dodge made the switch to 4-valves first, but although I have no concrete figures to go by I can remember reading several folks writing that their mileage was pretty poor for the first generation of 24-valve motors in comparison to the older

12-valve versions. I don't really know why.

Cheers - Jonathan

Primedia has a brand new magazine out called "Diesel Power". A friend of mine has a copy of issue #1 that I recently read. It has a diesel truck shootout in it and did a very good comparison on the Ford, Dodge, and GM models available this year. You might want to check it out.

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Well that makes 10 of us then.

I will be driving unloaded 95-99% of the time, and it will be mostly highway. I really want a straight drive with a 3.4 or 3.55 ratio axle. I put a deposit on a Chevy but the guy sold it out from under me. I'll keep my eye out for a Dodge.

Clay

If you're looking at diesel as the low cost way to travel long distance, you might want to compare what it would cost to travel 1,000 miles with a small-8 or V-6 vs the diesel. Mileage will be about the same with gas engine, especially if you can't find a diesel with a high rear end ratio (they are usually lower ratios as the expected use is towing or hauling) but the purchase price will be a lot less for gas engine, and diesel fuel costs have gone up so much that it offsets any savings possible with diesel. Tune-ups added to the cost of operating gas engines in the old days, but we no longer change plugs, points, cap, rotor, adjust timing, carb, etc every 12,000 miles. It is not uncommon for a gas engine to go more than 200,000 miles, although water pumps, alternators, power steering pump, etc will need to be changed on either type of engine.

Just something to think about. Rising fuel costs have changed the old rules of thumb.

If you just want a diesel because it is neat to wake up the neighbors every morn>

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This is not what I have found, necessarily. Like for like, same rear ratios and engine size, diesels ARE more effiecient. Even factoring in fuel cost right now diesels seem to have the edge. Taking into account maintenace costs, gasoline wins for sure. Then add life span to that and it seems to be a wash. In other words, buying a used diesel or gas truck costs about the same long term.

Taking into account the next point diesel wins hands down!

neighbors

vehicle too.

One of my main goals! I really love the sound of a diesel.

One other thing I have noticed is that the larger the vehicle, Suburbans, Excursions and the like, Diesels really take the fuel mileage race. After doing research, i found that full size Suburban can get well over 20 miles to the gallon on diesel.

My plan at this point is to look for a Suburban and have the axle ratios changed to 3.42 or so. Still researching though.

Thanks all! Clay

This is really the way to go, in my opinion. Try to get a burban with a 6.5 and low mileage. You can also try for an Excursion with a 7.3 diesel but it is bigger and even a 2000 will still cost you something in the upper 20's. Unfortunately, diesels are hard to find so the cost will be the deciding factor not which brand is better. I have been looking for a burban with a

6.5 for 3 yrs now and haven't found one for sale and only found one on the road so you probably are going to have to look on ebay or something like that... and as another correction the 6.0 powerstorke, all parts that see heat are iron or steel the only alumn part is the valve train girdle which bolts to the top of the head and holds the rockers and such. Personally, I would stay away from the 6.0, it is a nice engine (I have one) but is so complex you just can't do more then simple maintenance on it. If you have ever seen a Ferrari engine disassembled, well a disassemble 6.0 makes the Ferrari engine look like a air-cooled VW engine...and unfortunately when the 07 emission laws kick in diesels will be even more complicated. At what point did they decide diesel exhaust was worse then gasoline exhaust? The black stuff is carbon soot, what's next a catalytic converter on a candle???

Good luck, mark

Not sure about Ford Diesels but I driven both Chevy and Dodge diesels. We use Chevy's at work and they all have automatic transmissions. The latest model is a 2002 and we get around 20 MPH on the highway. I drove the Dodge trucks while playing porter for my wife who sells Dodge trucks. I picked up and drove back to the dealership three in the last year. The best MPH came from a 2004 Dodge 2500 Quad cab long wheel base with auto transmission. I got 26 on the highway. This vehicle was brand new when picked up with only

3 miles on it. I had to drive it back from Tennessee to Louisiana so most of the driving was interstate with the cruise control set at 70 MPH.

Sarge

I have heard many good things about the new ford engine, but also a lot of bad things. Like the pilot injection not working correctly, and having to reflash the ECU with a non pilot injection set up, causeing the new 6.9 to be louder then the old 7.3 and even louder then the Cummins

Bud To those who have fought for it, Freedom has a flavor the protected will ever know. Anonymously scrawled on a bunker at Khe Sahn, RVN.

hex can be a little confusing..

0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 A 11 B 12 C 13 D 14 E 15 F

That would be why I like the higher level languages like C++

Adding and subtracting in Binary is a real brain twister too!

Many, many eons ago I was a tech rep. teaching the digital computer to AF technicians (It was the first airborne digital computer which was installed in the F106). I made a rash statement that I could do anything in Binary that they could do in Decimal. Some wise guy says "Yeah, lets see you do a Square Root". I put a rather simple binary number such as 49 (100011) on the blackboard and even to my amazement I was able to do it. Just don't ask me to do it now.

PI was a bad idea the injectors were not up to the quick computer pulses...the intention was to make it sound like a gasser. Why? A diesel should sound like a diesel.... The 6.0 does have a tinnier sound then the

7.3 but it is not a bad engine (I have owned a 7.3 and currently own a 6.0). The 7.3 did have internal mechanical problems that developed once chipped. The 6.0 hasn't developed any problems although if you chip it you will start eating head gaskets...

mark

A diesel should sound like a diesel - yes, but a diesel shouldn't also sound obnoxious. There are noise standards as well as emission standards. I can open the hood of my '04 Duramax at idle and have a conversation in a normal tone of voice while standing next to it. My friend's Cummins powered Dodge requires you to nearly scream at each other in order to be heard with the hood open.

Just an observation, but It seems like you are contradicting yourself by saying the 6.0L Ford has inadequate injectors and then go on to say it doesn't have any problems. I never did have any serious problems with the

7.3L Powerstroke motors at work, although it did seem that the performance fell off faster over the years than comparable Cummins powered units. It was the Ford tranny that was a nightmare, but I understand they don't use the E4OD behind a diesel any more (and with good reason).

Cheers - Jonathan

Aren't both the Cummins and International engines now using rail injection? I was thinking they went that way to compete with the Durmax performance.

With my Durmax my wife's only comment has been "It sounds like the wind blowing" as the turbo winds down.