I am new to this forum, and did some searching for answers to my questions, but didn't readily find anything. I've had my 98 2500 club cab long bed for about a year and a half, and am getting 15-18 mpg running empty, around 12 mpg pulling a 29' 5th wheel trailer. It has 170,000 miles on it and seems to be running very well. I've had the timing adjusted and synthetic lubricants put in everything - which didn't seem to change anything.

With diesel at $2.50 per gallon, I'm interested in a cost-effective method of improving economy. No modifications to anything at this point. Even though I've got the 12 valve engine, I'm quite happy with the power. My main interest is improving economy. If the power improves as well, that's fine. Any suggestions as to what my first options should be?

 

you have nice economy now...whats ur timing at? 16degrees seems to be the popular medium....i noticed that the biggest difference is ur right foot...i pretend like i have an egg under there....and i have also become one of those abnoxious truckers that coasts to red lights so i never have to stop..saves a bundle..stop n go is the worst thing...drive like its abig rig and coast to a red so u never have to accelarate too much ....change ur fuel filter if u havent in a while...keeps the rpms below 2000...and since u have a 5speed u can really baby that right foot

Andrew

 

Thanks for the quick reply! The work order from the mechanic that did the timing shows 16 deg. I'm pretty light on the throttle now, although when I first got the truck I was a bit enthralled with the power (I previously had an 89 Suburban with a 6.2 diesel - loved the Suburban, but the engine was a dog!). I did get a bit over 20 mpg with my Dodge driving around in Glacier Park (without trailer) at the 45 mph posted speed.

I guess my problem is that I know several other people with Dodge diesels, both 12 & 24 valve, and they all claim to get better mileage than I do.

 

they lie ur also on winter fuel right now that will cut 2 mpg right off...if ur getting 20 then thats the good average...i wouldnt expect much more

 

Your economy sounds like it is right in there where it should be. My truck is around 18 overall. If I'm real easy on it , about 19.5 is the best so far. 16 deg on timing should be good. Keep your filters changed regular, and inflate your tires to close to max pressures. I keep mine 5 under max inflation. The tire tread makes a big difference in mileage too. The cheap 40,000 mile tires will give you the lowest fuel economy while the high mileage tires will give better economy. The tread design affects it too, go with a good highway tread with a high mileage rating. You could ask the tire dealer about which tire has the hardest rubber and gives best economy and mileage. It's the proverbial "you get what you pay for" theory. Also develop an easy right foot and keep your speed down some. 45 to 50 gives me the highest economy if I can keep my sanity and not fall to sleep.

 

good idea to check those tires yeah...but i have to say this when i was anewbie to this truck i check that im supposed to have the rear tires at 80psi so newbie me inflated it to 80 in the summer (EMPTY) and rode around...nasty surprise when i wore out the center of my tires due to overinflation...so now im at 40-45psi rear empty and i found thats a perfect balance

 

I'm running BFG Commercial All Season 265/75 R16's. I have them inflated to the recommended 80 psi in the rear, but the tires are too new to have noticed any wear yet.

 

watch that inflation...i think those recommendations are for inflation when the exle is maxed out!! to level out the rubber wear during full load!...but u never know urs might be different...keep checking ur tires...thats an expensive trial and error method unless u check it all the time...i was really upset when i noticed my wear

 

You may be getting a bit better, you have 265 tires, doubt the speedometer is corrected.

 

80 psi inflation when the exle is maxed out.

I get on a flat serface,start off with air around 60 then lay flat to see if all the tread is flat, if not let out more air till it is all flat.

This is how we do the big tires like 44" supper swampers.

 

Since 265/75/16s were the upgrade tires from the factory on a 2500 the spedo should be right shouldnt it.If you have 4.11 thats the mileage killer empty.I have a 3500 and I get 20mpg all the time with some town driving.

 

The speedo cannot be accurate with both 245 and 265 even if they were an option. Unless it has been corrected it will be accurate with the tires that came with it. That is generally 245. There is a difference in diameter between the two sizes.

If it is accurate with the 265 your mileage is correct but if it is accurate with 245 and you have 265, you are actually getting a bit better than the speedo says.

 

The speedometer/odometer isn't accurate, and I've taken that into account in calculating the mileage. When I bought the truck, it had 285's on it, so it is closer to accurate now than it was. It has the 355 rear end.

 

I have a 95 automatic an when I got it, the truck had 50k miles on it. The truck was a dog and got 16.5 miles to gallon. I was not pleased. I had never heard of TDR then , however I remember what I changed on my Turbo Diesel Toyato 4x4, timing, that was the first thing that I changed that had any effect on power and mileage. I run around 18. and that is were I like the way it runs. That gave me 19.5 or so also. I have changed the overflow valve, and a lot of other things to see if it would help. The exhaust was given a little going over also. I did not change the 12 exhaust housing though. The bigger aircleaner seemed to make a little difference. I also have a #10 plate and a 3 k govenor kit. My afc housing is slid all the way forward and the plate is forward also.
I have installed 215 injectors with a very thin washer and now I have gotten 23 miles to gallon on several trips. I have a stock transmission, automatic, 4x4 with 3.54 gears. I have a hard bed cover also, but I got that when I bought it an it got 16 then.
For towing an max economy I have to wonder if a 16 exhaust housing and a good cam from Piers or who ever, 16 deg timing, afc housing set for min smoke, 10 plate, would be a good start. Stock tire size like mine. I will not say the brand, but they are good high way treads, and 3.54 gears. I use to think that a automatic could not get good mileage , but that seems not to be the case. I still dont like a automatic, but it seems to be holding up good, even if it is a band aid on a bullet hole. good luck Jimk

 

Thanks for the info, although at this point I'm not smart enough to use it. About all I've done under the hood is change the oil. I know there are various aftermarket air cleaners, such as K&N. Is that what you refer to as a "bigger air cleaner?"

I don't know anything about plates - what are they? Where are they installed? (Please pardon my ignorance). What does the 3K governor kit accomplish? I'm afraid I also don't know what an afc housing is - or where to slide it. Same goes for 12 & 16 exhaust housings. Sounds like I may need to get a manual in order to make sense of the feedback I'm getting!