Now have 90K miles and wondering if at some point the valves are supposed to be adjusted on this 2005 5.9?? Runs great and hate to start fixing something that is not broken!!

 

STANDARD PROCEDURE - VALVE LASH ADJUSTMENT AND VERIFICATION
NOTE: To obtain accurate readings, valve lash measurements AND adjustments should only be performed when the engine coolant temperature is less than 60° C (140° F).
The 24–valve overhead system is a “low-maintenance” design. Routine adjustments are no longer necessary, however, measurement should still take place when trouble-shooting performance problems, or upon completion of a repair that includes removal
and installation of the valve train components or injectors.
(1) Disconnect battery negative cables.
(2) Remove cylinder head cover (Refer to 9 -ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - REMOVAL).
(3) Using the crankshaft barring tool #7471–B, rotate crankshaft to align damper TDC mark to 12:00 o’clock position.
(a) If both number one cylinder rocker levers are loose, continue to next step.
(b) If both number one clylinder rocker levers are not loose, rotate crankshaft 360 degrees.
(4) With the engine in this position, valve lash can be measured at the following rocker arms: INTAKE 1–2–4 / EXHAUST 1–3–5. Measure the valve lash by inserting a feeler gauge between the rocker arm socket and crosshead (Fig. 32). Refer to VALVE
LASH LIMIT CHART for the correct specifications. If the measurement falls within the limits, adjustment/resetting is not necessary. If measurement finds the lash outside of the limits, adjustment/resetting is required.
(5) If adjustment/resetting is required, loosen the lock nut on rocker arms and turn the adjusting screw until the desired lash is obtained:
² INTAKE 0.254 mm (0.010 in.)
² EXHAUST 0.508 mm (0.020 in.) Tighten the lock nut to 24 Nm (18 ft. lbs.) and re-check the valve lash.
(6) Using the crankshaft barring tool, rotate the crankshaft one revolution (360°) to align the damper TDC mark to the 12 o’clock position.
(7) With the engine in this position, valve lash can be measured at the remaining rocker arms: INTAKE 3–5–6 / EXHAUST 2–4–6 . Use the same method as above for determining whether adjustment is necessary, and adjust those that are found to be outside of the limits.
(8) Install the cylinder head cover (Refer to 9 -ENGINE/CYLINDER HEAD/CYLINDER HEAD COVER(S) - INSTALLATION).
(9) Connect the battery negative cables.
INTAKE
0.152 mm ( 0.006 in.)MIN.
0.381 mm (0.015 in.) MAX
EXHAUST
0.381 mm (0.015 in.) MIN.
0.762 mm (0.030 in.) MAX.
note:
If measured valve lash falls within these specifications, no adjustment/reset is necessary. Engine operation within these ranges has no adverse affect on performance, emissions, fuel economy or level of engine noise.

 

That was the long answer. Short answer, no, you don't need to mess with it unless there is an issue. Some folks say there is a sweet spot, but the gains are minimal IMO. If you do decide to mess with it, then I highly recommend getting the barring tool, it makes life a lot easier.

 

This looks like a very complicated and precise procedure which I would hesitate to trust to a dealer!!! They would take my money and probably never do any of this, especially do it properly none the less. I think I will leave Mr. Cummins alone ! If it ain't broke don't fix it.

 

It really isn't difficult at all. Set of feeler gauges, a wrench, allen wrench, torque wrench, the barring tool and misc tools to take the cover off... hour- hour and a half job at most. Look me up if you ever want to do it, I'll walk you through it.

Worst part is laying over the front of the truck to get to everything. A thick blanket over the hood latch fixes that pretty well.

 

2006 Factory Service Manual calls for adjusting valve lash at 135K miles for Schedule B and 150K for Schedule A (light duty).

 

I was going off the 04/05 book... thanks for the info.

 

Between 100k to 150k is when most will check lash. After that its likely you wont need to touch them again.

 

not hard at all, I've done mine twice and once when the head gasket was replaced

 

That part about the blanket is a very good point. Without some form of thick padding over the hood latch, I can guarantee that things will get very uncomfortable, very fast. It also helps if you have very long chimpanzee arms. Those last two cylinders are tough to reach. The very last one is VERY hard to reach.

As Madhat said, a barring tool makes life easier, but it is possible to SLOWLY turn the engine over using the alternator nut. Not recommended, but possible.

 

I use a fan wrench 36 mm turns the engine over easy, just mark the TDC with some paint. Done it that way for years. Will not work on 2013 and up since the fan was changed to larger size

 

I did mine at 50k, 150k, 250k for what its worth. Engine finally gave up the ghost to a broken piston ring on #6 at 295k. Now I'm just breaking in the rebuild... 1000mi so far, so good! Not sure when I will check them this go 'round, but likely at 50k again. Its a relatively easy task, so why not check them as often as you feel comfortable. Personally, I like to know things are in spec.