How often should you adjust the valves on a 5.9 Cummins?
every 135,000 miles
Valve lash, for example, is something that should be checked at least every 135,000 miles on a Cummins diesel engine, although many people adjust it even sooner. We’ve heard of valves being out of adjustment at 90,000 or even 70,000 miles, so checking them is a good idea.
How do you calculate valve lash?
To determine the valve lash, subtract the squish from the desired valve opening lift. The cam in the graph is for a flathead, using squish of 0.002″ the valve lash should be 0.0127″ or 0.013″. The exhaust could be set a couple thousandths larger to allow for thermal expansion.
Should valve lash be adjusted hot or cold?
For an engine with cast-iron heads and steel valves, you can expect the lash to tighten up a couple of thousandths of an inch as it heats up-so for the cold lash you would set the valve lash a couple thousandths larger than the cam manufacturer’s recommended hot lash setting.
What is valve lash clearance?
Valve lash is the available clearance (or gap) between the rocker arm and the tip of the valve stem when the lifter for that valve is sitting on the base circle of the cam lobe (when the valve is intended to be fully closed).
How does valve lash affect performance?
Since the valve cannot move until all the running clearance (valve lash) has been taken up, the amount of valve lash you use affects the engine’s performance. If you decrease the amount of (hot) valve lash, for example, the valve will open slightly sooner, lift higher and close later.
What happens if you have too much valve lash?
Too much or too little valve clearance can result in poor performance or a rough idle because the engine can’t “breathe” normally and operate at peak efficiency. Too much clearance means the valves will likely clatter and, over the long term, cause damage to the valves, camshaft lobes or rocker arms.
Is it time to check the valve lash on your Cummins?
As you can see by the dirt and oil leaks, we figured it was probably a good time to check the valve lash on this 200,000-mile Cummins, as we’re sure it had been a while. At a shop, a valve adjustment can cost you hundreds of dollars, but it’s actually something quite simple you can do in your own driveway.
How often should valves be checked on a Cummins diesel engine?
Valve lash, for example, is something that should be checked at least every 135,000 miles on a Cummins diesel engine, although many people adjust it even sooner. We’ve heard of valves being out of adjustment at 90,000 or even 70,000 miles, so checking them is a good idea.
What maintenance is required for a 24-valve overhead system?
The 24–valve overhead system is a “low-maintenance” design. Routine adjustments are no longer necessary, however, measurement should still take place when troubleshooting performance problems, or upon completion of a repair that includes removal and installation of the valve train components or injectors. Disconnect battery negative cables.
How long does it take to adjust a gas valve?
In addition to a 22 or 24mm socket (which most people don’t have lying around), the procedure can be done with basic handtools and takes about an hour or so, depending on your work pace and how many valves need adjustment.