Back in March, my #2 intake rocker loosened on me about 40 miles from home. I ended up driving it home with the pushrod beating on the rocker arm, obviously with loud tapping. A few days later I changed the #2 pushrod, roller lifter, and rocker arm, however the noise remained. Since then I've had the heads off and I made sure everything pretaining to the valvetrain was tight and clearanced properly but the noise remains. What could be the source of the noise?

 

Not to question your efforts, but are you sure you don't have another loose item on an adjacent valve?

Another thing to inspect is the spring and retainer. A cracked damper spring can make an awful clicking noise.

 

I am very positive. The heads are new as are the springs and the noise was unaltered. When the motor was apart, I inspected the pushrods and rockers and neither showed any abnormal wear. However, did did not inspect the lifters or cam. The noise seems to come from the middle of the engine but it is hard to pinpoint.

 

If you are able to remove the valve covers without much effort, a quick hand test should locate the loose rocker. Refer to a manual that explains how to adjust valves. It usually starts with #1 cylinder and says that #?? is also at TDC. Follow the directions to do all the cylinders. Just wiggling the rocker will tell you which one it is or twist the pushrod . A noisy rocker will shake/twist, a normal rocker is tight. Just remember, cylinders must be at TDC.

 

The rockers are lashed properly. This isn't anything blatantly obvious because like I said, I would have ran into it durning/after my head install.

 

To narrow down the source of the noise, an automotive stethescope helps. Placing it at various locations on the engine will tell you which cylinder is making noise, letting you concentrate on that location.

 

Compare the location of the adjuster nut to the other rockers. Also compare the motion of the valve in question to the other 7, using a dial indicator.

I'd be inclined to suspect a damaged cam lobe if either of those things are different.

Otherwise, look at the valve spring. It's probably a broken damper.

 

Well, that makes a little difference. Follow RB's advice in checking lobe lift. (Is this a newer cam?) You might also take a look at the camshaft end play/thrust. If the cam is "walking", the oil pump / distributor drive or even timing set could be "talking". As long as the intake has come off for lifter replacement, you shouldn't have too much trouble checking cam end play. Even if the intake is on, you can check play through the distributor hole, but you won't be able to measure it easily.

I'm presuming this is all on your '89, which should have a roller cam and lifters. And if you're still using the Crane aluminum rockers, you might want to inspect the trunion bearings and races on all of them to make sure you don't have a cracked needle bearing, cracked race, or even a broken trunion.

 

These are some of the ideas I've been looking for. I know all the set screws on the rockers are in the same spot, I noted that durning my final lashing. I will check valve lift when I get a dial indicatior. As for the walking cam, could this be from a loose roller cam retainer plate or something else? BTW, just to clarify, you suspect the damaged lobe on the one that loosened up correct? Thanks for the ideas guys.

 

i,m having the same problem with my engine. i have install new roller lifters, push rods and replaced the rocker arms with comp cam 1.52 roller rockers, i still have the same problem. here are some more thing i have tried, 30w-50woil, set valve lash from comp cam, gm, chilton manuel. If you find out what the problem is please post it. i know we are not along.