Ticking,belching grey smoke and low oil press.

[buddyo]

2004 Silverado 1500 Z71 4wd
5.3L engine 4L60E transmission
190000 miles. Stock truck

I bought this truck 2 years ago and have put 6000 trouble free miles on it in that time. It runs smooth and quiet. Until this morning. It started with no problem but ran extremely rough and belched grey smoke out the exhaust. There was also a ticking sound, like a lifter would make. Just one steady tick that increased with rpm’s. Occasionally I have heard it in the past on start but it would quiet down immediately. I’m getting a dtc P0300 (multiple cylinder misfires).
The truck has had low oil pressure since I had it- 8psi@ idle & 40psi @ speed. I’ve checked it with a manual gage @ the sensor to verify it, but I never had noises from valve train. I had oil pump replaced along with o-ring but made no change. Blew out gallery from sensor to oil filter, no problem there. I’m leaning towards a problem with camshaft problem, maybe a spun bearing? I would tackle the P0300 code but the ticking noise concerns me. Any suggestions?

[CamGTP]

Pull the valve covers and take a look, make sure all the rockers are on there and that you have no broken valve springs.

 

A scan tool that can read live data will show you what cylinders are misfiring and will make it way faster to figure out where you need to look.

 

If the rockers/springs are good, the spark plug and wires are good as well has compression, then it might be internal with the camshaft/lifters.

[Ian Mills]

The oil on startup could be related to the PCV. I did a head gasket one time and afterwards we had that smoke happening on startup. Turned out to be a bad PCV. Maybe it was a coincidence that it went bad when I had the heads off or maybe it was related, who knows. If the PCV is old on your truck I would see if there's oil getting inside the intake which would be a sign of a bad PCV.