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Looking at a used Duramax

5K views 35 replies 19 participants last post by  TanTahoe 
#1 ·
I looked at a 03 Chevy Duramax this weekend, had about 120,000 miles on it and body and interior is in great shape. But looking under the hood it has a K&N filter on it and is missing the plastic covers over the engine. It also seems a little slow but not really sure what to expect. Is there any easy way to tell if the injectors have been replaced or the engine been worked on? Without knowing the previous owner I don't want a truck that has been modified much at all.
 
#2 ·
Go to a dealer with the VIN. They should be able to give you the history on it. 03's had an extended coverage for the injectors. I think it was 7 years or 200K. I would guess they have already been replaced at some point. I would pay somebody to test them before I bought it. They get like 4000 to replace them.
 
#3 ·
Why do people put K&N filters on diesel engines that have not been modified? I know with the power strokes, the stock air filter flows a ridiculous amount of air, and can hold 3# of dirt. They last 100,000 miles.

My rule, is never buy anything with a k&n filter. If somebody was trying to gain extra power by doing that, what else did they do that you can't see?
 
#4 ·
I don't know about the K&N air filter deals. Everything under the engine on my truck is bone stock minus the programmer. I would say, get the VIN checked out at a dealer, or if you are serious about the truck, pay for a carfax (don't ask for a freebie on here). I don't know what the 03 had. One of my diesel douche buddies would know though. I think it's either the LB7 or the early LLY. LB7's had injector problems. As nTaylor44 said, they had an extended coverage on them.

120k is nothing for a diesel. My 2006 LBZ has 264k and it runs like brand new. I also run Standyne performance formula diesel fuel additive every fill up to help keep my injectors clean and working at 100%. If you do end up getting a Duramax, I highly recommend using Standyne just by the personal expedience I have had with it.
 
#5 · (Edited)
Its an lb7. My 03 has a factory replacement k&n filter. I gained 2mpg with that filter compared to the fram filter. I will continue to use that filter. No k&n on any offroad vehicles though. I use 1-2 quarts of atf per tank. 200k and get right about 19.5-20.5 on the highway. With exhaust, programmer, filter. That's not city only highway.
 
#22 ·
So you think 24122 members are going to change injectors themselves? Do you realize there was a class action case pending on the injector issue that the great bail out wiped off the books. The 2003 duramax injector issue is/was more than just a maintenance issue.
 
#23 ·
Notice I said most meaning the majority but not all. I am not a duramax fan all I am saying is if you want to buy a truck that is 11 years old plan on putting some money into it. You made it sound like the truck was junk replace the injectors and drive. If the money to replace injectors sounds high I would recommend not buying an 11 year old diesel because you probably won't like the other bills that will start rolling in shortly.
 
#24 ·
I know it's 11 years old and might need some attention, but injectors vs maintenance items is a huge $$$ difference. Also given the odd situation under the hood makes me think there is something going on, who would put a intake on a truck and not mess with more of it. I really don't want something thats been messed with by a diesel ricer or something. No stacks on it at least.

The more I look into it the more I think there is a problem with this thing, should it feel fast? I punch it getting on the highway and there is a 2-3 second lag while you hear the turbo spin up and then it goes a bit better than my 5.3 suburban. Not much better though.
 
#32 ·
The LB7 is not going to break any land speed records stock, the LLY and the LBZ started getting bigger turbos that take less time to spool because they are a Variable-geometry turbocharger, the LB7 I believe has a traditional style charger that makes boost at a much higher rpm and takes longer to spool. Should be quick but not fast. I know that a lot of people really like these trucks and an intake is really not that big of a mod, a lot of people will do an intake just because they like the look under the hood or because they think it will make the truck faster. If the injectors are good, I say go for it or look for a 2004.5 that has an LLY motor.
 
#26 ·
No. The t case wears through after a lot of mile. My 03 is quick. Long bed dually crew cab. Love the truck. Put ~30k on it. It now has almost 200k on it and it starts great, runs great, pulls great. Don't know if the injectors were replaced or not. More than likely. I just ordered a fass fuel system for it. Help save the cp3 and injectors. I service my filter every 10k so I haven't seen any dirt in my intake yet. So I'm gonna keep running the k&n for now.
 
#27 ·
Isn't the hesitation you speak of the turbo spooling up?
Also known as turbo lag?
The plastic pc missing on the engine is the resonator cover?
Sometimes plugged , along with a cold air intake to try and gain more of a whistle out of the turbo.
DURAMAXFORUM.COM
All the info you need to know.
 
#28 ·
I also agree with the oiled filter comments.
From what I have researched a cold air intake will only really start to make a difference on motors producing over 500hp.
I have an 04 max with 105,000 and I did the pump rub fix (transfer case)as it is referred to just for my own insurance.
Still no injector work for mine.
 
#33 · (Edited)
Well I did gain over 2mpg by putting the aftermarket filter in it. That's the only plus I found. But its worth it to me. I went from 13.7 city to 16.1city. So that's an extra 80+ miles per 32 gallon tank. But working on medium and heavy duty diesels professionally for the last 7yrs doesn't make me an expert. I do not drive my truck daily. More like once a week and on trips. I only put 28k on it in 3yrs. I am happy with my 03. I do think I got lucky with a good truck though.
 
#34 ·
Well I did gain over 2mpg by putting the aftermarket filter in it. That's the only plus I found. But its worth it to me. I went from 13.7 city to 16.1city. So that's an extra 80+ miles per 32 gallon tank. But working on medium and heavy duty diesels professionally for the last 7yrs doesn't make me an expert. I do not drive my truck daily. More like once a week and on trips. I only put 28k on it in 3yrs. I am happy with my 03. I do think I got lucky with a good truck though.
Ive put 23k on mine since January 2nd :(

I really need a second vehicle!
 
#36 ·
Over on duramaxforum.com, a lot of those guys like the S&B Dry cold air intakes. Mine is still stock and will be replacing the the air filter with a new stock one soon. They claim the stock intake on the duramax is good for around 500hp and 550hp if you do the air intake mod(remove front plastic part from air box).

And as stated, duramax owners remove the 'engine cover' and plug it to get a loader turbo with a deeper tone out the exhuast. I removed mine and plugged it due to the rubber boot cracking. Didn't really make a difference on my truck but its all stock.
 
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