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fullthrottleguy

2003 Duramax Silverado - Buying advice needed

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I am not a big Diesel guy and the one's I have bought have all been new and Fords. All my Chevy's have been gas. But I know where there is a very low mile mint condition loaded  2003 Duramax I am thinking of picking up. 

I have heard of injector issues and just saw LRS post about $6500 to repair an Allison trans - so I need some advice

What I know about the truck  1 owner, 4x4, 68,000 miles, Its garage kept. Its the fourth car in the family and gets used to just hauler a Kayak around. It was just at the dealer for glow plug replacement and all injectors checked. Oil and filter change records from the Dealer since new. 

I keep hearing you only want a 2005 - are these any good?

Any advice is appreciated I want to pull the trigger this week before it gets advertised.

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$6500 is for a fully built trans and TC.

The Allison will last several hundred thousand miles of not abused by big power adders. 

If the price was right, I'd go for it.  

My 04 is due for injectors, but they have not lived a sedate life...  3300+ in the pulse width column for a long time. ;)

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2 minutes ago, Kraut_n_Rice said:

$6500 is for a fully built trans and TC.

The Allison will last several hundred thousand miles of not abused by big power adders. 

If the price was right, I'd go for it.  

My 04 is due for injectors, but they have not lived a sedate life...  3300+ in the pulse width column for a long time. ;)

Thats clarifies a lot - I figure 68K miles and no leaks   I should be good for another 60K no issues ...

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What is the asking price ??  If priced low enough to compensate for upcoming injectors, then I would go for it.  The trans should not be the concern from what little I know about the Duramax. 

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I don't know much about the LB7 other then each generation gets better then the last.  2006-2007 were the best years and I can't believe what people are asking for them all these years later.  My 2006 LLY just hit 388k miles.  As you know I tow a lot and only had the trans done last year at ~350k miles.

If the truck is priced right and as clean as you say then it is probably a good buy.

 

Common LB& Duramax problems

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The LB7 Duramax is decent motor but there were a few problems.  Head gaskets can go and injectors will be problematic.  My 04 popped a head gasket at 180k.  Its $3500 + usually to have someone do all of the injectors.  You can do it yourself for under $2k but it is a pain in the rear job.  My 04 was a non-California emission truck.  No cat and no EGR.  My stock Allison went 260k before I it needed to be rebuilt and it pulled heavy alot.  Keeping any tuner under 90hp will help extend the Allison life.   At 68k miles I would think there is a lot of life left before you would have to address some of the known issues.  

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Oh another issue on early 4x4 Dmax trucks was the transfer case pump rub.  Design flaw and it will eventually rub a hole in the transfer case.  There is a kit to fix it.  

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Alex, I had a 2003 and had to do the injectors.....once that was done it was an AWESOME truck........ You will love it. If the deal is good GRAB IT....they hold their value and knowing the way you treat your stuff....You will make money when you let it go........

This time .....give me a heads up so I can buy it off you once you pimp it all out with all the goodies! :icon_smile:  Post some pics!!!!

:poule:

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44 minutes ago, POULE43 said:

Alex, I had a 2003 and had to do the injectors.....once that was done it was an AWESOME truck........ You will love it. If the deal is good GRAB IT....they hold their value and knowing the way you treat your stuff....You will make money when you let it go........

This time .....give me a heads up so I can buy it off you once you pimp it all out with all the goodies! :icon_smile:  Post some pics!!!!

:poule:

Thanks everyone - really helpful and Poule its near perfect and I will call you first 🙂  He is down the street and told  me they would give him 9500 on a trade in , he said give me 9700 and its yours, otherwise he going to advertise for 10K.  Its hard to find values on these or at least to find any under 200,000 miles, let along under 70K

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5 minutes ago, fullthrottleguy said:

Thanks everyone - really helpful and Poule its near perfect and I will call you first 🙂  He is down the street and told  me they would give him 9500 on a trade in , he said give me 9700 and its yours, otherwise he going to advertise for 10K.  Its hard to find values on these or at least to find any under 200,000 miles, let along under 70K

That's a great deal.

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If you don't want to buy it, I WILL...just saying.

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1 minute ago, L.R.S. said:

That's a great deal.

I thought so Jeff, the 2005's are going for 25K to over 30K for low miles .  I can't find a comparison on the 03 under 100k and like new inside  and out - I figured when he said 9700 that they were dogs or something . I guess I am going to over there at lunch tomorrow

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I would jump on that deal for sure.  even at 3-5k in repairs/upgrades if needed in near future, you're still doing very well.

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Sounds like a good deal!  

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That is a killer deal, What's his #, I'll give him 10k:lol:

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I had 03 duramax and loved the truck. I replaced the first set of injectors at 50k then 75k and was getting ready to put the 3rd set in at 100k. I used strenadine diesel additive pretty religiously. Just a bad design. Zero other repairs other than that. 

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Posted (edited)

LB7 is actually one of the strongest engines from factory and IMHO, better than the LBZ everyone hypes up. You can get them with 0 emission equipment from factory (no egr or cat and it has a factory catch can for PCV) which means the intake runners wont gum up with 1/2" of crap (yes, this happens when PCV vapor combine with egr exhaust, its terrible to clean out). Injectors on 04.5-10 wear out after 200k but not in the same way LB7 injectors go. The plus here is LB7 injectors are half the cost AND they now have a new injector out with a SAC style nozzle on them that will cure the last issue LB7 injectors had, the damn VOC nozzle. Swapping to the SAC injector nozzle has shown these injectors are going as far or father than the 04.5 and up injectors. I would suggest a tune for them though as they are a higher percent over stock VOC and can be smokey depending on how you drive. the later years develop high return rates of fuel which leads to hard starting and drop in fuel mileage and can also cause performance issues or codes for low rail pressure. The LB7 does not blow the fuel pressure relief valve like 04.5 up do so running a tune that ups rail pressure wont be an issue and if it does pop it open, it stays open or pops under low rail pressure so its easy to figure out. its extremely rare for them to pop though. Computer is super simple and tuning is a breeze in them. Head gaskets are no different than any other year duramax. GM had a shit time with them from 01-07 in keeping them under the heads at over 200k but its mainly from tuned trucks. 01-02 they had a very bad run of them and 95% were replaced under warranty. they changed to better stuff in 03-04, then on the LLY motor they changed again and created issues again. a built allison will be around 6-6500 these days (man i remember when i paid 4500 back in the day for my first built trans from mike) but you dont need it and honestly if the truck is left 100% stock, that trans can outlast the engine. A factory rebuilt with warranty is 3-3500 iirc.  thats installed. These engines are much less prone to broken cranks or cracked pistons like the 06-16 trucks are. the pistons are thicker and when GM decided to go to lighter pistons in the newer years, instead of removing weight from the fly weights on the crank, they just added weight back in on the balancer, thus adding more leverage to the snout where 9/10 times the crank breaks right behind #1 main journal. yes the rods are weaker but with the tuning people have now, there are LB7's and LLYs in the 11s and 10s even on a stock factory short block. 

the only draw backs to the engine is the fact the injectors are under the valve cover which makes replacing them not as simple as later years, lack of interior gadgets, and what USE to be injector issues. thats changed now as stated. I would pick that thing up in a heart beat. it would not hurt to see if these injectors are original. if they are, they are prone to bodys cracking and the engine "making oil" which can take your bearings out or the solenoids dieing and creating a very loud fuel knock. they will have the typical VOC nozzles as well which causes the haze and balance rate issues you normally see.

At 65k, you will need to watch the transfercase for "pump rub" as mentioned. you can do a little preventive maintenance and throw a merchant automotive or kennedy diesel pump rub plate in the t-case and stop any issues. while its apart, upgrade the shift mode fork to the newer style and the slip yoke to the new nickle coated one. that will stop any "bump" you get when coming to a stop and ensure 4wd works every time (this is assuming its 4wd). change the allison spin on filter, change the trans fuild and change the internal filter asap. ill bet it hasnt been touched and it needs to be done at MIN every 50k, 30k is a better interval. Be sure to use DEX3 only as well, DEX6 will cause it to leak and dry out seals. I would also really look over the hoses for the turbo coolant. these often do not get replaced when the rest of the hoses normally do and will split on you. there is 3 on the LB7, one of which is right behind the fan pulley coming off the water pump bypass tube. that one ways gets missed and sucks to change but needs to be done. other one is on the pass side right by the turbo by the fuel rail and final one is the obvious one running to the upper rad hose from the turbo. 
 

beyond that, there may be little things that pop up like gauges in the cluster dieing as they normally do on 03-07 trucks or if it has auto air, the hvac some times needs a reset and so on. 

Edited by Chevy1925

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8 minutes ago, Chevy1925 said:

LB7 is actually one of the strongest engines from factory and IMHO, better than the LBZ everyone hypes up. You can get them with 0 emission equipment from factory (no egr or cat and it has a factory catch can for PCV) which means the intake runners wont gum up with 1/2" of crap (yes, this happens when PCV vapor combine with egr exhaust, its terrible to clean out). Injectors on 04.5-10 wear out after 200k but not in the same way LB7 injectors go. The plus here is LB7 injectors are half the cost AND they now have a new injector out with a SAC style nozzle on them that will cure the last issue LB7 injectors had, the damn VOC nozzle. Swapping to the SAC injector nozzle has shown these injectors are going as far or father than the 04.5 and up injectors. I would suggest a tune for them though as they are a higher percent over stock VOC and can be smokey depending on how you drive. the later years develop high return rates of fuel which leads to hard starting and drop in fuel mileage and can also cause performance issues or codes for low rail pressure. The LB7 does not blow the fuel pressure relief valve like 04.5 up do so running a tune that ups rail pressure wont be an issue and if it does pop it open, it stays open or pops under low rail pressure so its easy to figure out. its extremely rare for them to pop though. Computer is super simple and tuning is a breeze in them. Head gaskets are no different than any other year duramax. GM had a shit time with them from 01-07 in keeping them under the heads at over 200k but its mainly from tuned trucks. 01-02 they had a very bad run of them and 95% were replaced under warranty. they changed to better stuff in 03-04, then on the LLY motor they changed again and created issues again. a built allison will be around 6-6500 these days (man i remember when i paid 4500 back in the day for my first built trans from mike) but you dont need it and honestly if the truck is left 100% stock, that trans can outlast the engine. A factory rebuilt with warranty is 3-3500 iirc.  thats installed. These engines are much less prone to broken cranks or cracked pistons like the 06-16 trucks are. the pistons are thicker and when GM decided to go to lighter pistons in the newer years, instead of removing weight from the fly weights on the crank, they just added weight back in on the balancer, thus adding more leverage to the snout where 9/10 times the crank breaks right behind #1 main journal. yes the rods are weaker but with the tuning people have now, there are LB7's and LLYs in the 11s and 10s even on a stock factory short block. 

the only draw backs to the engine is the fact the injectors are under the valve cover which makes replacing them not as simple as later years, lack of interior gadgets, and what USE to be injector issues. thats changed now as stated. I would pick that thing up in a heart beat. it would not hurt to see if these injectors are original. if they are, they are prone to bodys cracking and the engine "making oil" which can take your bearings out or the solenoids dieing and creating a very loud fuel knock. they will have the typical VOC nozzles as well which causes the haze and balance rate issues you normally see.

At 65k, you will need to watch the transfercase for "pump rub" as mentioned. you can do a little preventive maintenance and throw a merchant automotive or kennedy diesel pump rub plate in the t-case and stop any issues. while its apart, upgrade the shift mode fork to the newer style and the slip yoke to the new nickle coated one. that will stop any "bump" you get when coming to a stop and ensure 4wd works every time (this is assuming its 4wd). change the allison spin on filter, change the trans fuild and change the internal filter asap. ill bet it hasnt been touched and it needs to be done at MIN every 50k, 30k is a better interval. Be sure to use DEX3 only as well, DEX6 will cause it to leak and dry out seals. I would also really look over the hoses for the turbo coolant. these often do not get replaced when the rest of the hoses normally do and will split on you. there is 3 on the LB7, one of which is right behind the fan pulley coming off the water pump bypass tube. that one ways gets missed and sucks to change but needs to be done. other one is on the pass side right by the turbo by the fuel rail and final one is the obvious one running to the upper rad hose from the turbo. 
 

beyond that, there may be little things that pop up like gauges in the cluster dieing as they normally do on 03-07 trucks or if it has auto air, the hvac some times needs a reset and so on. 

Great Info  - Thanks - I think a lot of people will find it helpful - all the feedback is making me rush over this morning to pick it up

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I hope your in your truck on the way to buy it now at that price.

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Buy it! I'll give you 11k 😂

Seriously though, now we need to see this thing! Pics please! Also, how do you not know about these trucks when you know everything about everything??? LOL

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17 hours ago, fullthrottleguy said:

Thanks everyone - really helpful and Poule its near perfect and I will call you first 🙂  He is down the street and told  me they would give him 9500 on a trade in , he said give me 9700 and its yours, otherwise he going to advertise for 10K.  Its hard to find values on these or at least to find any under 200,000 miles, let along under 70K

Buy that truck before someone else does. that is a screaming deal on a low mile 4x4 dmax. I literally just sold my dads truck yesterday, 2004 lb7 fully loaded with 114k on it and sold for 20k.....

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1 hour ago, Chingon619 said:

 

Buy it! I'll give you 11k 😂

Seriously though, now we need to see this thing! Pics please! Also, how do you not know about these trucks when you know everything about everything??? LOL

I am picking up in the AM - I'll post some pics. 

LOL -  sorry if I come off as a know it all. Diesels are just outside my scope. They just seem "heavy"I would build everything out of Aluminum and Titanium if I could - big ole cast iron stuff is just weird

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28 minutes ago, fullthrottleguy said:

I am picking up in the AM - I'll post some pics. 

LOL -  sorry if I come off as a know it all. Diesels are just outside my scope. They just seem "heavy"I would build everything out of Aluminum and Titanium if I could - big ole cast iron stuff is just weird

I own a 2003 and love this truck,I did have to do the injectors at 93,000 I did it myself and it took me and a friend of mine 16 hours and it is a pain in the ass.I do have a step by step on how to it yourself and that saved me. Scoop that thing up ,sounds like a great price .

  Johnny

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My 01 had 330k on it when I sold it.  Was a great truck, all stock except for cold air intake.  Injectors replaced under warranty early on, then they didn't need replacing again until 320k, even then it was only 3 on one bank.  FICM went at 305k although I think that was due to an over aggressive powerwash.  The CP3  injection pump at 310 ish.   It never needed a trans rebuild and I tow  an 18k 5th wheel.  It did have the pump rub issue.  Overall was a great truck.  The one you are looking at sounds like a good deal.

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Well?  Where is this gem?

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