Hi, I was diagnosing a problem with a 1997 4x4 with a 4.3L. It had a loud banging noise even @ idle. Determined that it was the hydraulic lifters. I soaked all 12 new valves in oil, installed them & torqued all nuts to 40 ft-lbs. The engine has the hydraulic valve, push rod, rocker then valve for intake/exhaust. So only 1 nut in the rocker to set. I read in my manual 2 spin rod then turn nut 3/4 but sometimes I couldn't turn it on some valves. I even put #1 @ tdc then #4. How do I initially setup the hydraulic valves / nuts in the rockers ? Can I "fine tune " the nuts with the valve covers off & running as it still makes a bit of a clacking noise ?

 

With the net lash arrangement of these engines, you torque down the rocker arm bolt and its done. There is no adjusting them. Your manual is likely a Chiltons or Haynes which covers many different years since what you read does not apply to your engine.

And I have never heard a valve train noise that was described as a "loud banging". That is typically reserved for bottom end noises.

 

Hi, looking to do hydraulic valve setup on 4.3L Vortec from 1997 4x4 Blazer. Read a manual & it read to tighten rocker nut until pushrod feels a slight drag & then tighten 3/4 turn. However, 1/3 or so of these nutd inside rockers would bind uo after 1/2 turn or so. Even tried 1/2 @ #1 tdc, other 1/2 @ # tdc. Other suggestion was tighten all nuts inside rockers @ 40 ft-lbs. Still some noise after installing 12 new lifters & pre-soaking in oil for 1/2 hr or so. Tried 20, 30 then 40 ft-lbs, still noise. Not as bad, but still there & new install of good oil. How should I set up hydraulic valves, get rid of excess clatter afterwards. Want this '97 2 run smooth like my '01 that Runs like a 12 CYL Jag !

 

*Combining with your previous thread...*

Did you check over all of the push rods to make sure they were straight? Did you use the proper lifters?

 

The issue I had a few months back ended up being a Ruined Cam Lobe and one flatten roller on the Lifter. The 100K mile Engine was running fine for the 10,000 miles we drove it since we bought it. Then 100 feet from our driveway one night, Knock knock knock. While trouble shooting, Sometimes it was much quieter then other times. The range was from Tapping to Banging. The oil was fine Temperature was fine. It came out of no where, it came suddenly. I hope you don't have this issue.
When we tore it down to replace the Cam and all the Lifters, The bad one had plenty of oil on it. Mystery

 

A wiped cam lobe is not unheard of on these motors.

This could be determined using a dial indicator with enough extensions on it to reach down to the lifter from the top of the head (if the intake is on). Rotate the engine at least twice and record the total cam lift as indicated from the lifter. Compare with another cylinder on the same valve (intake or exhaust) working your way through all of them.

The problem seems to stem from a metallurgical defect in the cam blank prior to machining. One or more lobes are not hard enough to stand up to the abuse and they simply flatten out.

 

In a way I'm glad to hear you say this. Because since we put it back together and my daughters back to driving it ( about 3000 miles ago), I get a tight sphinkter waiting for a phone call.
Since it seemed like such a mystery, No Oil starvation and no temperature issue, I get nervous that there is something that's going to cause it to happen again. When you tear it down and find the problem but not the cause.. scary.
When these Cams go, they go from OK to Crap that fast? I realize that teh engine is turning fast but still 1500 rpm and in a second it went from quiet to knocking in a second.

 

When you are dealing with a hardness problem on a high pressure surface, yes, it can go from ok to gone in a very short matter of time. Typically, the defect is not located right at the surface, but further underneath. As the cam wears in, the harder outer layer may get worn away uncovering the defective area causing the short demise. Or, considering the relatively high spring rates and the aggressive opening and closing ramps used on roller lifter applications, the loads may cause the lifter to crater itself into the opening ramp of the lobe and wipe it clean in one pass.

 

Hi, thanks to everyone for the above information. I am also needing the torque spec for the mounting/adjusting nut that is set inside the rocker. This sets the tension initially for each valve on the valve train. Also, would I just set them all cold at any engine position or would you do some at #1 tdc then say rotate 360 degrees ? I inspected the cam, lifters rods & rockers. Replaced all 12 lifters as 1/2 or so were hard to compress & wouldn't rebound even in warm oil. Still have a little tapping noise, got the timing dead on with a long screwdriver & a lucky touch in the blinded distributer hole.

 

Just when you relax...........

Well. Friday night KNOCK KNOCK KNOCK.

Sounds the same as it did when I posted the Quote above. 50 K miles since I fixed it the last time. Oil changes religious at 3000 miles. Used as a commuter car not as a Tow vehicle. I wonder if there was a production batch that had an issue or maybe they were made ( incorrectly)in a different factory. There is no reason why this should have happened the first time let alone again.Lifters and Cam were NAPA stuff not Autozone chinese.
Not worth redoing. anyone want a decent '99 Car with no engine?Dark Blue