For the last six months I've been trying to get rid of the incessant ticking that appears under light throttle from 1400-2000 rpms. It's taken so long because I have to wait on the Alaskan weather to clear so I can work in the driveway. That ticking was like CIA waterboarding to me and drove me crazy over the winter. It sounded like non-stop marbles rattling in a glass jar.

I started out reading every conceivable thread about this issue. The most common causes offered were CP3 "timing" adjustment, injector rattle, loose injector line brackets, or bad or dirty injectors. Some also say it's normal and to just live with it. Most suggested fixes seemed like bandaids and not viable long-term solutions. I believe in fixing the problem, not just making the symptoms go away. I also believe in trying the simple things first and wasn't about to run out and drop the coin for new injectors or pump.

First I tried synchronizing the CP3 pump stroke with the piston stroke of the engine. It took several tries but I eventually found the sweet spot and some of the clatter at idle went away (a pleasant surprise) but the ticking was still there.

The second thing I wanted to try was adjusting the valve lash. The weather turned sour on us and today I finally got around to adjusting the valve lash. Hallelujah, the ticking went away! Of all the threads I read none of them really pointed to the valves as a problem. I didn't really consider it either because I only have 67,000 miles on the truck and valve adjustment isn't really routine maintenance, it's usually something you do if you happen to have the cover off.

I discovered that 5 of the 12 possible adjustments were out of spec on the high side...3 intake and 2 exhaust. One intake valve was waaaay too loose...like .040 inches when it's supposed no more than .015. Also, many of the lock nuts were so tight I had to use a breaker bar to get them loose. The torque on them is only supposed to be 18 ft-lbs.

After my success with the valve lash adjustment, I also tightened down the injector line brackets just for good measure. And I have no doubt my injectors are dirty since I tend to do a lot of idling in the cold. I need a good hard trailer pull to burn off the carbon. Conveniently, I live 2 miles from a Cummins regional service center and will go get some of their injector cleaner, which I hear is very effective as well.

I guess if I have anything offer for the ticking, it's to check/adjust the valve lash even if you think your engine doesn't need it yet. Had I not checked, I might have spent thousands on new injectors I didn't need.

Stew

 

Good report Stew. Thanks for sharing.