2004 2500HD 6.6 duramax

[greatmizzou]

Question...

 

I am not familiar with 6.6 duramax at all.  Ive been keeping my eye on HD gas trucks and have an opportunity to get a used duramax at a farm auction.  Im going there for a used trailer but I might set aside some $$$ for the truck. 

 

All i know is its a 2004 2500HD with 6.6 dmax and 180k ish miles, crew cab long bed

 

I am very familiar with gmt800 trucks with the 5.3 vortec.   I am an absolute unknown with Diesel.   I know enough about what to look for under and around, and if jt looks good Ill drop $ on it, unless it goes too high in price.  Heres some questions:

 

1.  What type of engine maintenance and costs would I need to dump into it to make it a reliable tow veh?  I heard of glow plugs, they sound magical.

 

2.  Not too worried about the Allison transmission, but what maintenance should get done? Costs?

 

Tell me anything else I should be looking for or concerned about!

[diyer2]

Simple to me.

If your'e aware of the maintenance required to keep a vehicle reliable it's the same dance.

Change/check all fluids, check belts, brakes, etc.

Just go over it well and replace anything you determine needs to be.

Cost?

Do it yourself or have it done?

Diesels do require more oil. The fuel system more expensive to fix.

Making it a reliable tow vehicle only will come to be after owning it and making it reliable.

Good Luck

 

 

 

[riverbanks]

You could do the litmus test in the antifreeze,checks for combustion gasses, biggest problem I see around here is somebody throws a bulldog tuner on and maxes it,that's when problems start,stretched head bolts,so,adult owned,never been hopped up on roids,good to go

[Formulabruce]

99% chance this has a 5th wheel in the bed ( hence the long bed  needed for 5th wheel)

 So being towed, how does the tranmission run at temp?, does it have a bigger cooler up front, any service records.

Unless it runs perfect and quiet, no big smoke, and body has no rust, I would limit the money to 10K.

 Its an auction and buyers CAN NOT ask the owner a thing usually.

 These long bed trucks are a pain to park unless you have a lot of room.

 Look underneath at back behind rear bumper for rust and rockers for rust, and bottom of front fenders for rust.

 Cab mounts at back of car are for falling through issues.

 Good luck !

[jake111]

2004 was a transition year from 1st gen (LB7) to 2nd gen (LLY).  Look at the RPO codes in the glove box to see.  Each has their own distinct list of issues.  Maybe the biggest for each:

LB7 - injectors (1st set were probably replaced under warranty).

LLY - overheating (towing up long grades, especially in the west); injector connectors (#2 and #7 notorious; but the injectors hold up very well!); headgaskets (especially if overheated or had tuner).

 

I usually recommend the LLY (I have one) only for people who are likely to work on it themselves (maintenance, looking at known potential problem areas).

 

Regardless, if it's had a tuner I would walk away.

 

I hate that it sounds like I am trying to scare anyone away from these trucks.  I've had mine since new and plan to keep it "forever" because it's a GREAT truck (but I've taken steps to prevent overheating, worked on the #2 and #7 connectors, protected the known wire rub-thru spots, etc.).

Edited August 20, 2019 by jake111

[Dixon700]

Also with the mileage, if the injectors have never been replaced you might want to have about $4k set aside(less if you're doing the labor yourself).  Check for cross members and bed being rotted out also. 

[greatmizzou]

I passed and am now looking at another gmt800 duramax Listed $15,000

 

I know these allison 1000 transmissions hate extra HP, how do I find out if the truck had a tune?  Dealer?  All I have is a bluetooth obd2 with torquepro.     I think a good visual inspection and drive test will pretty much answer any other question I have..

 

truck has a black bowtie and smoked aftermarket tail-lights.   That is a huge turnoff for me!  Am I alone with that?

 

 

[davester]

I believe with the GMT800 trucks, you likely can only tell if there is a tune installed at the moment.  If it was installed in the past, and then reverted to stock, you can't tell it was installed.