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Tool Hut
Tool Hut, ASE Certified Technician
Category: Chevy
Satisfied Customers: 515
Experience:  Owner of a mobile diagnostics company assisting auto technicians with difficult vehicles
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I just purchased a 2002 2500HD with the Duramax/Allison

Customer Question

Hi. I just purchased a 2002 2500HD with the Duramax/Allison combo. First ,it runs very well with minimal noticeable smoke. Trans feels strong too. It has appx 200K on it. My concern is I got it from a wholesaler in north Philly & got no repair or maintenance history on it. I did my first oil change the other day & was surprised to find it had about 17qts of liquid in it. It also was very wet underneath. I know it's only supposed to carry 10quarts of oil & have read the injectors can leak fuel into the oil. WTH?? I'm a die hard GM guy but this is a bad design. Anyway after changing the oil it also now has much better oil pressure, idles even better & runs a helluva lot smoother then before . How can I check to see if the injectors are in fact leaking besides draining it out & checking on the quantity that comes out? If it had enough fuel in the oil to cause a leak somewhere ( still haven't found where it was leaking) Would that stop leaking with the proper amount of fluid now in the oil pan? NEXT, I would like to do a couple power upgrades to it. I'm not looking to do a ton of things to it so what is the easiest way to get a bit more power ? Air intake, exhaust, ?? My first diesel In a daily driver. I work on military diesels most of the time. Thanks, Randy.
Submitted: 1 year ago.
Category: Chevy
Expert:  Tool Hut replied 1 year ago.

Hi, My Name is***** have over 20 years experience repairing vehicles. I am a ASE Certified Master Auto Technician. I am confident we can resolve your problem together.Please remember I don't know your skill level. I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies to get to a satisfactory resolution.I also try to give all of the information you may need expecting a positive rating. If there is any reason I cannot get a positive rating please let me know.

I am a die hard GM guy also and am also a huge fan of the duramax. GM did a lot of things wrong with the early version. If you do some research you will find that the 02 had a really bad reputation for injectors. Good news is now you can purchase a set for less than 1K. It is a big job but not real difficult. If you intend to keep this truck purchase a tech 2. a chinese clone would work for this vehicle. you can find them less than 300. The injectors do need the flow rate set when they are replaced. requiring the tech2. The first upgrade I would do would be an airdog lift pump and water separator. The 02 is not filled with emissions restrictions so there is not a lot to remove to get some power.

As far as testing the injectors: If there is fuel in the motor then there are injectors in your future. follow link for purchase. I am in no way affiliated with this company. just some research and seem like a good combination.

https://www.dieselogic.com/product/2001-2004-duramax-lb7-66l-diesel-injector-set/default.aspx?gfid=p552-c245&gclid=cj0keqjw3auubrdj1lnqyljy-4sbeiqakpu_vxtmkpmzfvhnbeddorlivco8rfpay-cqv1txnwewojaaass58p8haq

Customer: replied 1 year ago.
Thanks, ***** ***** read the 1st gen Duramax had injector issues. I read also that GM was replacing them under warranty. Would that apply to me even though I am not the original owner? Is there a way , if I remove the valve covers to 'see" if they are leaking or of they may have been changed already? Will altering the flow rate improve power/performance or does it just regulate how much fuel the injector releases? Don't want to make this thing a thirsty pig. Had plenty of that with my 454's. What would I remove to add power as far as emissions? This is my first Duramax. Give me any GM Gas engine & I'll build it from scratch but this diesel is a new one on me.
Expert:  Tool Hut replied 1 year ago.

I dont think they are warrantying them anymore. It would be worth a call to a dealer. Would not matter you are not original owner. The injectors spray directly into the cylinders there is not a good way to determine a leak without a scanner. As I stated the 02 does not have the emissions on it that can be removed to increase power. The first upgrade I would do would be a lift pump with a 2 micron fuel filter like the air dog. This will prevent a second set of injectors. The next move would be to remove the exhaust and put a full flow system on it. No Cat or muffler.

Customer: replied 1 year ago.
How effective are open air filters on diesels? I suppose it works on the same theory as any engine, " more air in , more air out, better breathing, etc..."
Thanks for your help on this. I may be back. Lol.
Expert:  Tool Hut replied 1 year ago.

there is a lot of cold air boxes available. I have not seen where they are effective

Expert:  Tool Hut replied 1 year ago.
It has been a couple of days since I have heard from you. Do you still need assistance? I have also noticed that I have not received a rating from you. If for some reason you question did not get answered please reply. I am only compensated for my time when you leave a positive rating. Your understanding is appreciated.
Customer: replied 1 year ago.
Thanks again. Sorry I've been away for work with the Army. No cell use or internet in the training lanes here.
Where is the lift pump installed in the system? Is it a replacement for the fuel pump?
Expert:  Tool Hut replied 1 year ago.

The only fuel pump from the factory is the CP3 pump which is a suction pump. It is not designed to suck fluid the distance from the fuel tank causing premature failure of the CP3. The lift pump and fuel filter is mounted to the frame rail and goes inline with existing hoses. You will notice immediate improvement in power and fuel mileage. I recommend the Airdog 100. I have installed several and have been quiet and trouble free.