help diagnosing a miss
 

my truck has like a missing sound but only under a slight load. free reving it doesnt do it, to the floor it doesnt do it, but just driving normal it has a weird missing sound.. kinda sounds like a tractor. it just started doing it a week or so ago any idea? wouldnt think itd be injectors bc it would miss all the time if it was. maybe timings slipped?

its a 94 12v 5 speed, 4gsk, no plate, gutted afc, intake, 4in exhaust

valve out of whack? sounds like an easy and inexpensive thing to check to me. someone care to collaborate?

hm well ive had the truck for around 8k miles and ive never adjusted them... maybe its due cuz i doubt the guy b4 me did it

how do you adjust the valves? what tools you need?

NOTE: Engine coolant temperature should be less than 60°C [140°F] for adjustment.

1.Remove the plastic fuel pump drive cover located on the front of the engine.

2. Using the barring tool, Cummins Part Number 3824591, rotate the crankshaft to align the top dead center marks on the gear cover and fuel pump gear. (You can also rotate the engine by using the alternator nut)

3.Remove the rocker lever cover and gasket.

4. With the engine in this position, lash can be checked on the following rocker arms: 1l, 1E, 2l, 3E, 4l, and 5E.

5. Adjust the lash to nominal specifications.

Lash Specifications
mm in
Intake 0.254 0.010
Exhaust 0.508 0.020


Tighten the locknut and remeasure.

Torque Value: 24 n.m [212 in-lb ]

6. Using the barring tool, Cummins Part Number 3824591, rotate the crankshaft 360 degrees, or until the timing mark on the fuel pump gear is pointing down 180 degrees from top dead center. Reset lash for rocker arms 2E, 3l, 4E, 5l, 6l, and 6E.

7. Check the gasket for cracks in the silicone covering.

Replace the gasket if cracks are present.

8. Inspect the rocker lever cover for cracks or other damage.

9. Place the rocker lever gasket on the cylinder head.

NOTE: Make sure the gasket is properly aligned around the cylinder head capscrews.

10. Install the rocker lever cover and capscrews.

I found this hope it helps yeah

ok ill do that asap, is there anything else it could be?

has anyone heard of the lobes wearing off? sounds like it may be a slight valve timing problem on only one cylinder... that's why i asked if it was a lash adj. problem- the more lash the longer it takes to open... had a valve cap break on one of the farm vehicles and did the same thing. but a worn cam lobe might do the same thing... you can check it with a dial indicator (set it up on the rocker to measure lift) and then compare with the rest of the rockers... no spec really needed as long as they're all about the same. just a thought. please someone jump in if he'll just be wasting his time:U:

well a buddy of mine (dodge mechanic that owns a 12v) said it takes a while to do it so i guess ill try it this weekend, i hope thats all it is

B Series Valve Adjustment

I use the last method, takes me less than an hour.

hi i have the same problem i just adj valves and still have same problem