Top end noise.

[nrocpops]

Full disclosure my truck is a1994 Chevrolet Silverado k3500. This is my first diesel. Experienced a cracked head. Replaced both with new heads from ssdiesel, great people, led to top end noise. Then replaced all the lifters and pushrods without removing heads, a challenge, top end noise still there. I have valve cover off now and don't see any obvious problem. Should I replace the plastic buttons? What should I look for. I saw one thread here where they had valve cover off without removing intake manifold, I would love to know that trick.

[DmaxMaverick]

Welcome aboard!

Diesel engines are usually loud enough to mask typical engine noises, such as the valve train. Many times, valve train, and sometimes suspected rod bearing failures, are simply nothing more than a noisy injector (worn out or improperly built). Diagnosis is simple. With engine idling, loosen an injector line nut at the injector (about 1/2 turn). If the injector is bad, the noise will stop, and it may or may not cause a more noticeable miss. If you identify a bad injector, swap it with another from the opposite bank, and repeat the test. If the issue follows the injector, the injector is, in fact, the problem (despite what it may sound like). If the issue remains at the cylinder, then the problem is not the injector, and may indicate other issues such as (but not limited to) wrist pin, cracked piston (or skirt), or valve/seat damage.

Another possibility, although not at the top end, is the crank pulley. It is rubber isolated, and will hammer when the rubber is gone. The noise can often "sound" like a knock on top. The balancer can also cause a similar condition, but is less pronounced. Check it too, while you're under there.

[nrocpops]

Thanks, I will try the injector test after I reassemble. Going to replace guide buttons while I have it apart maybe that will cure it.

[DmaxMaverick]

The rocker buttons are either broken or they aren't. If they're intact, it isn't likely the source of the noise. The buttons only keep the rockers from sliding sideways on the rack. Even when they fail, it can be years or decades before noticed.

[a5150nut]

Laying under your truck look up at the crank pulley. If you can see shiny spots on the tabs it is bad. Or pry on it a little to see if there is movement.

[ronniejoe]

The advice on the crank pulley is good and you should check it; however, I don't think the noise that it makes can be mistaken for top end noise. I would look the rocker arms over really well. I've seen the tips which rub on the valve stems wear pretty badly and make noise. I would also check the pushrod seat in the rocker arm. I've seen these wear badly and make noise as well.

Since you changed the heads, I think we can rule out a broken valve spring. I have seen this happen leading to top end noise also.

Hope you fined it.

By the way, the heads that you got from SS are likely Chinese knock-offs. Beware.

[nrocpops]

How much play should there be between rocker arm and shaft. These seem awfully loose.

[ronniejoe]

I don't know a spec off the top of my head. Look for wear on the bottom side of the bore. If it is excessive, you could be operating with lash which will make noise.

[sctrailrider]

How much play should there be between rocker arm and shaft. These seem awfully loose.

With the lifters pumped up and the arms bolted down their should be NO lash.

When things are right the lifter is pre loaded and their is no adjustment, if the rockers are loose as in you can lift them and their is clearance between the valve stem & rocker something isn't right, this is with a fully pumped up lifter..