2 Questions about 05 Duramax
 

My truck was down, so I borrowed my FIL's 05 Duramax to pull my velocity to the shoot out at LOTO.

1, the mileage sucked AZZ! The truck had gobs of power, but it got about 8mpg......is that normal? My f150 does better then that, but doesn't have near the power obviously.

2. It had some kinda of horrendous knock/rattle from the steering column. Any clue what could be going on there? I'd like to fix it for him, since he let me borrow the truck. In the little research I have done, it seems to be the intermediate steeling shaft I am guessing... Anyone changed, of fixed one of these? doesn't seem like a bad job. The steering/suspension is pretty tight, but its got a bad knock/rattle that sounds like its coming directly inside the steering column. The truck only has 93K on the clock.

1. My '04.5 LLY DMax pulled down 11 MPG towing 8,200 lbs. to LOTO from IL.

2. The stealer took care of the intermediate shaft problem so I never touched it. However, given your description and mileage, I'd look over the entire front suspension closely. Tie rods, idler arm, pitman arm, ball joints, etc.

How did it tow and how did you tow with it? Did you set the torque converter lock and set it to cruise control? Was it downshifting on the hills at all? When was the last time the fuel filter was changed? 8 mpg is a little low for pulling that boat.

Your friend isn't maintaining his truck very well. Steering shaft is about a 300 fix. 8 mpg??? Something wrong there.

Wannabe

Your Ford was broke and you complain about a running 10 year old GM? :D

Not complaining. I just figured a diesel should do better then 8mpg towing maybe 7K. Like I said the truck ran like a raped ape, just thought the MPG would be better....maybe not, I dunno....that's why I asked.

My FIL told me after I talked to him this morning, that the dealer has replaced the intermediate shaft already at 65K miles. In doing some reading looks like you can grease it?

He actually does take pretty good care of it, and rarely drives it (maybe 4K.year), it just started making the noise, and he is going to take it in, if we can't figure it out ourselves. Suspension, and steering are tight, no issues there. This is strictly like its inside the column/behind the dash.

Ask him when the last time the fuel filter was replaced. You need to replace the fuel filter on these at least every other oil change. Earlier duramax's at least every oil change. Also, the truck may feel like it runs awesome but it still could be low on power. If it is getting 8 mpg towing, I would have the injector balance rates checked. The early ones had injector issues.

early 04's were the last of the injector issues. 04 1/2 and newer didnt have the injector issues. get a GM fuel filter and GM air filter for it. i bet they hvent been changed in a long time. put a intermediate steering shaft in it that will get rid of the clunking. my 04 with a tuner and exhaust used to get 20ish towing a 28 pantera. the 05 should be at least 14-15mpg

My 2004 get about 10 pulling 11k boat trailer....

steering shaft is very known easy fix.

also the classic body trucks need front wheel bearings... they sell then whole hub, abs snesor, and all for 200 ish bucks 4 bolts and done.

04.5 just started the wiring harness issues lol, and the twice as expensive never in stock injectors

I'm pretty sure GM came out with a updated intermediate shaft that doesn't use grease. The issue with the intermediate shaft is that the grease eventually pushes out where the two shafts slide into each other. I think the newer ones have some type of rubber bushing in it.

Get the dorman shaft. Worked for me

is the truck stock or has mods ? I had a 05 for several years, had mods and edge tuner, but got about 11, when I got my 08 same deal had mods and had been tuned...got terrible mileage, had duramaxtuner do a swap out ECM and truck is great now...so sometimes just a bad tune will kill the mileage..

The one I had I had to put a new front end under the truck at 65k & again at 130K. About 131K the wiring harness went out.

The 2004 1/2 they made a change for emissions and caused all kinds of problems. As soon as I put a trailer behind the truck and temps were in the 90's the fan clutch would say engaged all most the whole time and would only get around 8 mpg. If the temps were cooler and the fan clutch would not stay engaged the mileage would go up to 11-13

If the dealer changed the steering shaft he put parts in that were not fixed of the issue. The fix came years later and the Dorman parts are the ones to get.

There is a plastic bushing under the dash that wears and allows the steering shaft to rattle, it can be replaced or squeezes slightly with a hose clamp. I put a clamp on mine more than 50k miles ago and issue has not returned. Check out dieselplace for a how to

The turbo inlet from the air intake is horrendous on the 04.5 and 05 trucks. Upgrading that to an 06 style elbow will free up torque, economy, and keep the engine running cooler while towing. Here is a little reading on the problem and solution: http://killerbeeperformance.com/indu...tion-overhaul/ . My 05 would average 12-13 hauling about 9K in the winter.

Pretty sure that's what it is. I actually read about it, and did the hose clamp trick the other night when I was back over to his house. Drove around the block, and no noise, so I think its fixed. thank you.

Those years with the 5 speed trans werent great on hwy fuel economy unless you stayed at 65. At 65 it shouldve been just under 2,000 RPM's and the higher you go over that the worse the mileage gets.

If it was getting 8 and its stock and you werent running 75+, then yes it needs some maintenance done.

My 2004 lb7 truck gets 8-9 no matter whats hooked on it, motorcycle trailer, boat, 38ft flat bed. But I also run 75-80 so I don't expect it to be good.

Rattle under the dash is the plastic bearing under the column, while the ISS is out make sure its free and replace as needed.

like mentioned..i used my buddys ..went from il to loto and back..kept it at 70 and avrived 22 mpg..towing my 18 donzi i got 15..standard cab 4x4...as for the rattle check the inner tierods..when they get loose they will make a banging noise..

Guess I'm a little late here, but I tried the hose clamp fix to squeeze the plastic bushing (07 classic D-max). I tried to install the hose clamp close to the end of the column but there are 2 support brackets welded to the column right where I wanted to install the clamp. These brackets make it difficult to get a hose clamp to stay put. The clamp wanted to slid off the brackets.

Picked up a 2 1/8" muffler clamp and installed it very close to the end of the column. Tightened it just enough so the plastic bushing could not be pulled out but not so tight it crushes the column. Worked like a charm.
Some guys have used a 2" muffler clamp but said they had to "make it work". The 2 1/8" clamp slipped right on.
Best $3 I ever spent.