04 Duramax problems? Would you buy one?

[CoreyZ71Sierra]

I can get a 04 Duramax extended cab 4x4 it's a SLE Sierra short bed. It only has 40, 000 miles on it. Sense i work at the Dealership they will sell it to me for $21,000. It has bald tires and the passenger doors have a bunch of touch up paint so i would have to re paint them. I checked the 8 digit of the vin and it's a 2 so it's the LLY 04.5 i heard these are the better ones and shouldn't have injector problems. I plan on beefing it up adding an exhuast, intake, chip, and ect. Will a duramax hold up with some of these mods? I heard they will blow head gaskets or it is common for them to go around a 100,000 miles. What year did they go to the 6 speed auto tranny's? I be leave the 04's are the 4 speed if not correct me. I really would like to get a cummins, but i can't find any at a good deal and the Duramax should ride better with the IFS. So what's your opinion?

[Quyonmob]

5 speed allison.

Do et.

[RichLockyer]

The engine will take pretty much anything you can throw at it until you start getting into nitrous+propane.
There's a reason propane is called "pane"

http://personal.linkline.com/rlockyer/llybad.wmv

The trans is the problem. The C3 clutch is the weak point once you start adding more than 40-50hp (and it can use some help stock).
Transgo makes a good kit for it.

Here's the dyno chart from my '06 LLY (LBZ with a factory LLY tune) with a Bullydog programmer on the 2nd level.
Would have been better down lower but the tech was having trouble locking the trans into 3rd. The '06 LLY went to the Bosch 32bit ECM and uses the CANDii interface... straight Tech-II won't talk to the trans.

http://personal.linkline.com/rlockyer/dyno.jpg

[SlvrdoHDmax]

About the only time they will blow the head gasket is if your pulling heavy in heat, and overheat the engine. It was "common" because GM made the turbo inlet too small with a tight turn. This causes thermal feedback from intercooler to radiator. Easily fixed with an inlet from a LBZ or from afe like I have. After that, you can forget the overheating problem. The 5 speed will hold +80hp tune decently, just needs to stay out of 5th if your getting heavy on the go pedal. They went to the 6 speed in 06. The only other problem I can think of is the injector harness. Over time #2 and #7 injector get a weak connection from the harness due to a sharp turn from wire to connector and the harness rubbing on a bracket. Some wire loom and the updated harness take care of that. In my case, the harness lost connection around 185k. I was able to bend the 2 tabs in the connector down to gain connection back, no problems in 5 months now. Mods like you listed will help the truck. Mainly exhaust, egr block or delete, pcv reroute, turbo inlet, and downpipe.

From purchase in October 2010, til now, I have about $180 in actual repair cost. 1 wheel bearing, and a turbo vane position sensor.
Overall, yes I would buy one

[CoreyZ71Sierra]

Alright here is the post no one wants to hear. I want to blow smoke once in awhile. My friend has an edge and it says with stock parts not to turn it past level 3 which he hardly gets any smoke. They recommend injector's, turbo, and something done to the tranny for level 5. He also told me the only way to get it to blow smoke is to put bigger injector's in. So what are all these guys doing with the quadzilla and EFI live tune's. How do they get there trucks to hold up to that much power? How will the 04 duramax stack up against an 04 Cummins. In my opion i have drove a few Cummin's and a few duramax's at work. Ranging any where from 04's to 06's and i have also drove an 09 duramax and a 08 cummins 6.7 and it always seems like the Duramax's are faster. I am really thinking about getting rid of my 07 Silverado which has been trouble free to go to this 04 duramax i just don't want to regret it. I noticed that the muffler has been taken out and replaced with straight pipe it looks like this was just recently done. Hopefully it wasn't getting out EGT's and they decided to do this to help. Other than that the truck is all stock.

[RichLockyer]

He also told me the only way to get it to blow smoke is to put bigger injector's in. So what are all these guys doing with the quadzilla and EFI live tune's.
For one thing, they aren't listening to Edge or your friend.
The Duramax injectors are more than adequate for as much as 800hp, and will blow a LOT of smoke, even on a 60-80hp tune.

[SlvrdoHDmax]

They will blow plenty of smoke on a small tune and stock injectors/turbo. My little Superchips is set on 80hp and itll roll anytime I want.
The main weak point in the Allison will be 4-5 upshift and 5-4 downshift under hard throttle with a tune or towing heavy in 5th with a large tune. If Im getting on it I just use the o/d lockout button and haul ass, once im up to speed, just ease off the accelerator and enable 5th again.
The main thing you need to make big power is a tranny/torque converter. Other than that, the stock turbo, injectors, and internals are good to about 500-550

[Stratosman]

I can get a 04 Duramax extended cab 4x4 it's a SLE Sierra short bed. It only has 40, 000 miles on it. Sense i work at the Dealership they will sell it to me for $21,000. It has bald tires and the passenger doors have a bunch of touch up paint so i would have to re paint them.

So they really want $23,000 for it :crazy:

[CoreyZ71Sierra]

So the tranny is the only thing to worry about? That's good because i don't want to change injectors or a turbo. How much would it cost to make the tranny hold up to a 100+ hp tune? I i don't tow to much mainly a small quad trailer or a car dolly. How do i keep the EGT's down if i run over a 100hp tune? What's the highest you should let your EGT's get to?


So they really want $23,000 for it :crazy:

They have it on the lot for $24.995 i am going to see if i can get it for $21,000 or $21,500 with it being serviced and the new tires. I was going to talk to the owner about it today, but i am holding off i want to look at a 06 Cummins on Saturday.

[lbajo1]

But i am holding off i want to look at a 06 Cummins on Saturday.

Get the Cummins with a 6spd!! :burn:

And you dont have to worry about doing Sh!t to your transmistion and you will Roll a LOT of smoke..

[RichLockyer]

So the tranny is the only thing to worry about? That's good because i don't want to change injectors or a turbo. How much would it cost to make the tranny hold up to a 100+ hp tune? I i don't tow to much mainly a small quad trailer or a car dolly. How do i keep the EGT's down if i run over a 100hp tune? What's the highest you should let your EGT's get to?
The Transgo kit, and as DMM said, keeping it out of 5th, will hold it together at 100hp.
The issue is the C3 clutch pack. It engages to go into 4th, then disengages to go into 5th.
Under hard acceleration running power, there's not enough time for it to cool between shifts and it will ultimately glaze same as if you constantly rested your foot on the clutch of a truck with a manual trans.

I bought an EGT gauge, but I never saw anything that bothered me even running the 50hp tune. Quite the opposite... I was surprised at how LOW temps would go at idle or light throttle when not building boost.

[CoreyZ71Sierra]

Get the Cummins with a 6spd!! :burn:

And you dont have to worry about doing Sh!t to your transmistion and you will Roll a LOT of smoke..

I am looking at Automatic Cummin's. I just had surgery on my knee 6 months ago and it doesn't seem to like a heavy clutch or would go with a standard. As far as EGT's whats the highest you should see them go 1400? They only get hot when your towing or running them hard right? I found a 06 crew cab is there anything better about a 06 than a 04.5? Will the 6 speed auto hold up to more HP than the 5 speed?

[SlvrdoHDmax]

I am looking at Automatic Cummin's. I just had surgery on my knee 6 months ago and it doesn't seem to like a heavy clutch or would go with a standard. As far as EGT's whats the highest you should see them go 1400? They only get hot when your towing or running them hard right? I found a 06 crew cab is there anything better about a 06 than a 04.5? Will the 6 speed auto hold up to more HP than the 5 speed?

Watch the auto tranny in the dodge..
Egts.. 1400 for a brief period of time, as in a couple seconds imo. I usually keep mine under 1200 and thats with getting on it hard with an 80hp tune. The 06 will be better. Little bit different in the engine and has 6 speed.

[SlvrdoHDmax]

I am looking at Automatic Cummin's. I just had surgery on my knee 6 months ago and it doesn't seem to like a heavy clutch or would go with a standard. As far as EGT's whats the highest you should see them go 1400? They only get hot when your towing or running them hard right? I found a 06 crew cab is there anything better about a 06 than a 04.5? Will the 6 speed auto hold up to more HP than the 5 speed?

Watch the auto tranny in the dodge..
Egts.. 1400 for a brief period of time, as in a couple seconds imo. I usually keep mine under 1200 and thats with getting on it hard with an 80hp tune. The 06 will be better. Little bit different in the engine and has 6 speed.

[RichLockyer]

The biggest problem with the Cummins....

It is quite possibly the best oil burner on the market.
It is wrapped in quite possibly the worst sheetmetal on the market.

I worked with a guy a few years ago who bought a RAM1500. That truck was in the shop at least once every 2-3 months.

The Cummins will outlast 5 RAM bodies.

[DarkCharisma]

I absolutely LOVE my '04.5 LLY-powered Duramax. I get compliments and comments EVERY TIME somebody rides with me or drives it... and it's stock, engine-wise. It's got gobs of power, will pull some great fuel mileage marks, easy to work over for more TQ/HP, easier to work on than the previous generation and is relatively free of any real problems.

The 6-spd came around in 2006. However, common consensus is that the 5-spd pulls better, as the double-OD is useless on the highway. I have no qualms with my 5-spd.

Your stock transmission can handle about 90hp over stock power output. Exhaust, intake, tuner is enough to make your truck feel like a rocket. It's recommended that you start running a lift pump if you're running tunes, to save your CP3.

Some things, in no real organized manner:

* Head gaskets are only a problem on trucks that were either pushing big power, or overheated regularly (or both). Mine has 160,000 miles of hard life and is fine.
* Injectors are not a problem if you don't run sh1t diesel.
* You will need to replace your Turbo Mouthpiece. The stock one is restrictive and contributes to higher heat and slower spool times.
* Overheating was a factory-acknowledged problem. Some have overheaters, some don't. Mine doesn't, and many have had great luck by just flushing the coolant system, replacing the T-stats, getting a bigger turbo mouthpiece and exhaust. If you want, there is an option out there to add a secondary radiator to your system if needed: http://www.dieselplace.com/forum/showthread.php?t=371427
* Injector harness rub can cause lack of power when it rubs through. This can be fixed easily with the "ice pick" trick and some heat wrap. http://www.dieselplace.com/forum/showthread.php?t=142114


All in all the second-gen Duramax is trouble-free aside from the mouthpiece and the harness rub, both of which are cheap and easy to fix.


Edit: Please don't "Roll smoke." That is quite possibly the WORST image of diesel owners you can project, and causes stupid regulations to crop up, as well as general hate towards diesel owners. Burn that fuel, not dump it out the tailpipe.

[Diesel Dan LB7]

Get the Cummins with a 6spd!! :burn:

And you dont have to worry about doing Sh!t to your transmistion and you will Roll a LOT of smoke..

manual transmissions are not un-breakable. The stock clutch on the Cummins isn't enough for the stock tune. And "rolling coal" is gay.

[SmokeyLLY]

Absolutely Love my LLY... I have a stock tranny and a hot EFI live tune from Fleece Performance. Other then that just an intake and exhaust and get 15 city and 19 highway. If your just doing small upgrades the stock ally will hold up just fine. I run mine at the drag strip and have done a truck pull with it with no problems. If you run a real hot tune like mine just turn off over drive and you wont "limp" your transmission. I have a smokey tune(hence the name SmokeyLLY) in mine and have gone about 40k miles with no injector problems. Fleece Performance said i am right at 500hp. Dont forget to put on tie rod sleeves if you go with any extra power and plan on driving it hard. I.E Boosted 4x4 Launches at the strip. No regrets with buying mine