2016 Chevy Silverado still has rough idle even after camshaft replacement


Looking for some input here. I have a 2016 Chevy Silverado 1500 LS, 4.3L LV3 V6. It was rough and loud when it idled, so I tore down the engine and found two of the camshaft lobes had been gouged as well as two of the lifters. I replaced the camshaft, the lifters, lifter guides, rocker arms, pushrods, valve springs, valves, valve seals, all the gaskets needed to get to the camshaft (head gaskets, valve cover gaskets, water pump gaskets), and I changed the spark plugs and the wires. I went through and torqued everything to spec, and in the proper torque sequence (according to the Haynes manual) for the head bolts and the oil pan bolts and timing chain cover bolts. I put the timing chains back properly also. For the initial startup after rebuild, I had the spark plugs out and took out the fuses for the fuel injectors and the fuel pump and turned the key to build oil pressure. Then i installed the spark plugs and wires, put the fuses back, and then I went to start the truck for the first time. It started up, but now it still sounds rough!!! It is a little better than before changing the cam shaft, but still rough nonetheless. See the video at the link below.

It may be a longshot to be able to diagnose from just listening to a video. There is some squeaking from the belt, which I’ll figure out, but why is the engine still sounding and running so rough on idle? If I push on the gas a little a smooths out, but on idle it is rough.

Should I be looking at replacing the fuel rails, fuel filter, fuel pump?

If you listen to the video, seems like a sucking sound almost. Is this the vacuum pump?

Any thoughts would be appreciated.


Did you liberally apply assembly lube to everything when installing it?

Normally, I do not want to rotate the engine by cranking until I already have oil pressure if at all possible. On some engines, you can do this by accessing the oil pump shaft and turning it independent of the motor. And this is even with liberal application of assembly lube.

It’s time to step back to basics and verify some of the fundamental stuff- compression, fuel pressure & volume etc

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Well, at least worn cam lobes were evidence of a problem. Vs seeing nothing on tear down. Was it only problem? Rings?

Guessing you had more than one problem, and you’ve fixed one now, but still have another (possibly plural). Not able to listen to your vdo, but here’s some ideas of things to check anyway.

  • Is the check engine light on?
  • Are there any current or pending diagnostic codes?
  • Are the battery and alternator working correctly?
  • Is the fuel rail pressure correct?
  • Is the warm idle rpm correct?
  • Does the exhaust gas come out of the tailpipe (warm idle) smoothly, the bursts repeating evenly and at a constant frequency? If you hold a dollar bill next to the exhaust pipe, it should be blown away from the pipe. Does it ever move towards the exhaust pipe?
  • Cylinder compression ok?
  • Intake manifold vacuum ok?
  • PVC system ok?
  • Air-tight from intake air filter to throttle body?
  • Any exhaust leaks?
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Just a thought. did you replace the intake manifold gaskets. and check vacuum hoses for leaks. A vacuum leak will cause it to run rough.

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What procedure did you follow for adjusting the rocker arms?

+1 for post above mine…

My 1st thought is what wiped the cam and lifters out, next where did all that metal go??

Looks like these engines have a lot of issues with carbon build up which can cause rough idling issues, also active fuel management issues…

Did you at least lap the valve while the heads were off and disassembled?? Or did a machine shop rework the heads??
A few off the wall things, did something (carbon etc) cause a valve to hang up and smack the piston causing the lifter/cam failure… Possible burnt valve, they will idle rough and smooth out with RPMs… With the heads off did you make sure none of the valves were leaking??? Check for valve to piston interference??

Did you use an OEM cam or an aftermarket cam? possible aftermarket cam might have a tighter LSA (lobe separation angle) causing a slightly rougher idle??

Have you hooked a vacuum gauge up and checked vacuum readings??
Have you pulled the valve covers to make sure no rocker arms are loose, either not adjusted correctly or new cam and or lifter wiped out again??
Lots of possibility’s,…

That was the only problem that I saw. I did a compression test of the cylinders and they were all consistently around 180 to 185 psi (with cylinder 4 getting up to 190 psi) so I don’t think it would be the rings.

I put a bunch of lube on the new camshaft, I let the lifters, rocker arms and push rods soak in new oil, and then also added lube to them.

I just followed what the Haynes manual said to do.

Ya I’ll have to do some of these tests. So far, compression test is good.