roughstock

Planning on buying an 04 3500 CTD QC Dually 4wd, auto. It has approx 70,000mi right now. It is in good condition, except small crack in dually fender, few small scratches on hood. What should I look for when going to buy it? What usually breaks, leaks, etc. I've heard that you should get a better fuel system? What about the auto trans? I tow a fair amount, usually loads >10,000lbs. It is all stock and has been treated well. My friend bought it in 06with 35,000miles, now he is going to get a new one and sell this one to me this spring.
I don't know if it is 04 or 04.5, Can someone tell me why this makes a difference? More HP?
Thanks for any input, this willl be a be a big jump for me from a hi mile 2wd 12 valve.
Thanks

XZILR8N

You should have posted this in the 2003 - 2007 forum. You might get more replies. However, I will give you my comments:

First you need to find out if it is 2004 or 2004.5, look at valve cover placard. It will show HP/Torque rating. If 2004.5 its 325HP/600 Torq. If 2004 it is 305Hp/555 Torq. Newer 600 engine had quite a few improvements and went to 4" exhaust. However, many will tell you that the 305/555 gets better fuel economy due to lack of 3rd injection event.

What to check: Put it up on a rack and look at it from bottom to top looking for any obvious abuse or leaks. Check service records if he has them. The auto transmission fluid and filter should have been changed at every 30K miles. What were oil change intervals? Has differential fluid been changed in both units? What warranty work has been performed if any? Does engine have most current flash (look on radiator cross member for update sticker). Look at oil dipstick and smell it. Make sure it is just oil, no diesel smell. Best way would be to take an oil sample for oil analysis to check for any unusual wear metals, since you might not know 1st or 2nd owner's maintenance history. What is fuel mileage in town and on hi-way. Typically mileage should run somewhere between ~14 mpg to almost 20mpg on hi-way. This really varies depending on driver style and terrain, tires, etc. However if its in the low 10 - 15 range it may be one of the more thirsty engines.

Weak Points: Does it still have stock lift pump? If so, its getting up there in mileage at 70k miles. Some fail early, some go well past 100K. Check U-Joints for play and tie-rod ends. Being an auto, it is not DC approved for an exhaust brake. I tow 10,000 lbs and there are times I wish I had an EB decending long or steep grades. But with tow-haul and good trailer brakes you can manage it just fine if you don't allow speed to build up on those type of decents. BTW, 2006 was first year for factory approved EB on the auto.

Take it out and drive it for a while to get it warmed up. How does it shift? Any unusual vibrations at Hi-way speed. Make sure it goes into 4 wd easily. Try out everything.

That's pretty much all I can think of off the top of my head. All in all, the 2004 models were pretty solid. At least mine has been. FYI - I bought mine new in Oct. 2004 and it has 42k miles on it now and has been problem free except for an initial leaky hydro-boost pump that was repaced in first 100 miles.

roughstock

thanks for detailed reply. I will repost in correct forum thanks.