Hello everyone! I'm a newbee here.
I'm thinking of buying an '02 2500 4x4 Duramax, but would like to know of problem areas to be aware of.
Don't be shy, I know all of the Big Three have their trouble spots.
Welcome! Well, if you are looking at getting an 02, the only real trouble area is the injectors. They are covered for 7yr/200,000 on the 01-02s. I would just have the VIN number checked to make sure it has a fairly clean history and you can see the warranty work done on it. The engine is covered for 5yr/100,000 mile warranty with $100 deductable after 36000 miles. I would keep a lookout for possible power adders that were on it. Obviously look and smell the tranny fluid. If you can get access to under the truck, check and see if the transfer case has been leaking. There is a clip that has been known to come loose and then you get a small hole wore in the housing of the transfer case. Have the wheel bearings checked for free-play. It seems even with everything stock on the truck that the front ones go at about 75,000 miles from what I have read on dieselplace.com.
As far as injectors...it it a crap shoot with them from what I have read. Even people with extra fuel filtration have had problems. For the most part it is from particles in the fuel clogging and blasting the injectors.
As far as programming. As long as you don't rag it too hard you can get by with the stock tranny. It is recommended that if you are going to run more than 100 hp tune that you upgrade the TC and clutches. If you plan on running 60 hp and lower, you shouldn't have many problems. You just have to remember to back out of the throttle before you shift into 5th and not force a 5th to 4th shift under hard WOT accelleration. You tranny should hold up to the programmer providing the person before you didn't rag it out with programmers.
The problems with the injectors and the pumps was an inferior seal that they were using in the assembly of the injection system. Once they figured out that was really the source of the problem it was well into the 2002 production year that they corrected it. The dealer should be able to run the vin number to see if the upgrade has been done. They are using a much better seal now. The year I prefer in the LB7 would be a 2003. They pretty much had most of the injection problems sorted out by then.
I have an O3 GMC. No problems with the truck in almost 100K. I have been told that injectors are a problem but haven't had mine replaced yet. I go to Baja at least 3-times a year for SCORE races and put several thousand miles a year with Pemex diesel. No Problem.
I am unhappy with my fuel economy, getting 16 mpg (I averaged over 20 mpg with my old Dodge and same type of driving) average with mix driving. Looking for upgrades now that will improve that. I have AFE's Stage II and it helped close to 1-mpg. Otherwise truck is stock.
Oh yeah, stock GM shocks suck. Bought new set right away and helped ride out a lot. Also BFG AT tires were a big improvement.
Allison/Duramax combo is the best out there. Drives like a gasser with all the diesel benefits.