gmc Towing an RV Trailer

[Hubexter]

Recently purchased a 2004 GMC 2500hd Diesel.

Open to learn about best maintenance practices etc

[Logan Lanfear]

Oil, fuel filters, air filters, trans, rear end.  All should be done if you dont know the last time they were done.  Then pickup whatever interval you prefer. 

[sdeeter19555]

Owner's manual is a good place to start...

Short that, as stated above, then follow the owner's manual.

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[redwngr]

Find out if you have an LB7 (early 2004) or an LLY (late 2004), sometimes referred to as a 2004.5)

 

Maintenance list that Logan posted, but add the transmission spin on filter. 

 

 

[davester]

grease the front end and the drive shafts u-joints if they have grease nipples.  and note that the idler arm has 2 spots to grease, an easy one at the joint to the middle steering arm, and a harder one somewhere along the shaft that the idler arm shaft rotates in.

[Hubexter]

Thanks everyone for your replys and tips!

 

Got the engine oil & filter changed, also greased every nipple under the front end. A bunch of em!

Spring I'll get the radiator & transmission flushed.

Who puts out a quality Duramax repair & maintenance manual? Haynes? Can't find "MOTOR" brand manuals?

 

Again thanks for all the help!  She is running good getting 19.5 mpg on hwy for starters!

[jake111]

You only asked about maintenance items . . .  The only thing I choked on was flushing the transmission.  Never flush an Allison.  Drain/fill and external spin-on is recommended by Allison unless the pan is dropped for some other problem.  Power flushing may ruin things, although "passive fluid replacement" just using the transmission pump is ok . . . but isn't necessary.  You can do several drain/fill cycles if you feel strongly about a more complete replacement, and consider using a TES-295 rated ATF like Transynd or Mobil Delvac ATF.  Oh, and DON'T use Dex-VI like GM says because it may eventually lead to leaking seals.  (Dex-III actually is still available, sometimes without saying Dex-III, like "for 2005 and older GM...".

 

There are 11 grease fittings in the front end.  

 

If you want to ask about heading off problems, then you need to say if it's LB7 (8th vin digit is "1") or LLY (8th vin digit is "2").  If it's LLY then I have a pretty long list of things to check.  I know, I've got one!

[StinkyCheese]

Get the fuel filter access door kit.  Or make your own.  Makes changing the fuel filter so much easier.  I'm assuming yours is in the same place as my '09.

[davester]

Really, the only manual to get is the full-service manual.  Either get it in print from helminc.com or ebay/amazon, or get an online subscription at helminc.com or alldatadiy.com (not that expensive, $50 for 5 years).

 

I used to buy haynes manuals, but if you compare them for different vehicles, most of the book is the same, with a relatively small amount of vehicle-specific information and when you have more than just a simple problem, the Haynes just doesn't cover it.

[diyer2]

Agree on the manuals.

Being a DIYer myself, the only manuals to own are the manufactures service manuals.

I have them for my vehicles, my Mercury outboard and my Honda ATV. The outboard and the ATV are carburated motors.

 

The full set of GM manuals are over $300 I think.  

All the other brands of manuals fall short on the info that is available in the manufacturers manuals.

[Wintersun]

Several things with these trucks. The front end should be greased every 3000 miles to avoid expensive repairs or a deadly accident. Second is that diesel fuel is extremely dirty and so fuel filtration is much more important than with a gas powered engine. Avoid bio-diesel as pre-2011 truck were not designed to run it and it can gel in cold weather and make for an expensive repair. For motor oil go with a quality dino oil that is for your area. A 5 weight synthetic is only needed and recommended where the temperatures regularly get below zero degrees. Change the oil every 5k miles as diesel crankcase oil picks up more sludge and soot as a result of the fuel being burned and so going to extended change intervals is foolish.

 

The Allison transmission takes two different classes of fluid and the one that the dealer uses requires a change every 2 years. The better ones like Castrol TranSynd can be changed every 4 year and I get it done at the local Allison dealer.