New (to me) '03. Recommendations?

[Mbschmidt]

Hey guys, I bought an '03 last week and would like to know what you think would be the mods I need to do immediately. I will use the truck as a daily driver, pulling a 4000# trailer through the hills here occasionally. I am interested mostly in power, economy, and longevity. I have 2 12-valvers and love them, but the 24 valve is completely new to me.



The truck is an 03 quad cab 4x4 auto with 134k on the clock.



Engine doesn't appear to have been messed with, all stock. Keeps about 20-30 psi oil pressure at idle at operating temp. Temperature stays about 190-200 degrees. A buddy of mine has a bully dog programmer he doesn't use on his SCORE stock full truck any longer and is giving me a deal on. I'm also thinking about putting a different air cleaner setup in it, and have heard that the exhaust manifolds are bad to crack on these trucks.



Auto transmission was rebuilt last February (@ 121k) and seems to work fine (still under warranty). Receipt states that converter was either rebuilt or replaced as well.



Front diff cover has a dent in it, and lower control arm(?) on left side has been replaced. Have receipts for upper and lower ball joints as well as axle joints and alignment all within the last month. The guy I bought the truck from told me he replaced the rear diff fluid within the last 3 months with synthetic oil, but didn't say anything about the front.



Other than that the truck is pretty straight forward, Needs an exhaust, has a little rust starting to bubble on the rear wheel wells, dash is cracked, but I'm not interested in winning any car shows.



Any input would be appreciated!

 

[JJPage]

If the lift pump has not been replaced, then that is a "first on the list", you can either go with a stock replacement that mounts to the fuel filter canister, no longer available at the dealer but Geno's does sell them. Or you can go with an aftermarket lift pump which incorporates a W/F separator and a 2 micron filter setup, such as Airdog or Fass.



The second item on my list would be to re-torque the injector cross tubes, they loosen over time and can cause alot of symptoms because of rail pressure drop. You will know right away if any are loose or are not evenly torqued, something you can do yourself.



The stock airbox is actually hard to improve on, you can add a cold air intake entrance by using 4" pvc and tubing installed from the bottom of the airbox to behind the front bumper, do a search, lot's of pictures available.



There are also quite a number of direct bolt on turbo back exhaust systems for around $300. 00 to $800. 00. Some of the good inexpensive systems are MBRP and Diamond Eye, another upgrade you can do yourself. I would upgrade to band clamps rather than u-bolt type crimp clamps, if you ever have to remove it you will be glad you did. The cracking exhaust manifold myth... is just that imo.



Enjoy your new truck, I love my 03. Jess

 

[Prairie Dog]

Congrats, you got the best year Cummins equipped truck money can buy!

JMHO of course. . I'm in no way prejudiced :-laf

 

[JDKammin]

The 03 should be a high pressure common rail engine. I did not think the lift pumps were an issue on these engines. The 24 valves in the 2nd gen trucks had the VP44 injection pump and lift pump issues.

 

[rscurtis]

Congrats, you got the best year Cummins equipped truck money can buy!

JMHO of course. . I'm in no way prejudiced :-laf

X2 on that comment.

 

[rbattelle]

I am interested mostly in power, economy, and longevity.

Unless this list is prioritized, the stock engine fulfills this entirely, right?



-Ryan

 

[DE Jeeper]

The 03 should be a high pressure common rail engine. I did not think the lift pumps were an issue on these engines. The 24 valves in the 2nd gen trucks had the VP44 injection pump and lift pump issues.

Common rail doesnt mean the lift pumps dont go bad. Its fairly common on the engine mounted lp's for them to fail around 100k. Genos has replacements or you can get a retrofit for an in tank one. If you are going to add power just get a Fass or similar. If you want to smoke like a feight train and have around 650 hp and 1250tq you can do what i did (see sig).



Other things that will soon go bad, injectors (suggest upgrade with F-1's when they do), apps sensor (mine go about every 100k), driveshaft and axle joints. I also have the rust in the fender wells so I think that will soon be a common problem for many. Also, if you tow a lot you may have problems with the pcm, the trailer lights run through it and they soldered the flasher relays rig to the board. One day I will get in there and resolder new ones or run wires for external ones, but in the mean time I run a tap in kit from Pep Boys.



Aaron

 

[mweiman]

2003 fuse box

Here is a good modification that I just learned, take fuse 46 and 47 out of the underhood fuse box which should be the trailer right and left turn signals. They should be 15 amp fuses from the factory, switch them out for 10 amp fuses so it doesn't burn the circuit in the fuse box instead of tripping the fuse as Aaron just mentioned. If you just have 1 turn signal on each side of your trailer I would think a 5 amp fuse might even be plenty. I would think switching your trailer turn lights to LEDs would lessen the strain on the circuit also. Another thing I have found is the wires going to the fan clutch are routed along the radiator and can rub a hole in it. Make sure they are secured properly and maybe put a spot of JB weld on the radiator so they won't rub through it.

Matt

 

[steved]

Unless your reading oil pressure with an aftermarket gauge; the OE gauge is "fake" and the reading is generated by the ECM based on a oil pressure "switch" and engine parameters.

Look for a wire that can rub through at the AC compressor... it controls the AC and the crank/cam sensor circuit and can cause performance issues.

Closely inspect all the ujoints, all mine failed by 75k... they don't get loose, but instead get extremely tight.

The issue with cracked manifolds was primarily a 2nd gen 24-valve problem. Not to say it can't happen to a 3rd gen, just that it is most common in the older trucks.

With today's electronics, if removed you would never know if the engine was modded or not... other than a few holes in the dash, I could have my truck looking very stock in about 15 minutes.

If it has aluminum wheels, there was a recall on some of the alloy wheels in 03 for cracking around the hub.

 

[dcherill]

The 03 should be a high pressure common rail engine. I did not think the lift pumps were an issue on these engines. The 24 valves in the 2nd gen trucks had the VP44 injection pump and lift pump issues.

the pump they are talking about is the transfer pump that feeds the high pressure pump.

 

[dcherill]

i have an '03 HO (305/555) and love it, it really is a great truck, i am sure you will love yours

 

[CToney]

keep an eye on front driveshaft. I would change all fluids they are cheap. Don't forget power steering. Check out my mods. Stuff was done as needed or for power, economy, longevity.