cadmaro

So I have an 08 Denali awd with 149k miles on it and it has had the cold start lifter tick/diesel noise that everyone say is common on these trucks for a while but it recently became worse and stopped going away when the truck warms up. It knocks pretty good on a cold start then gets quieter as it warms up and sound like a sewing machine above about 2500 rpm. some times it will randomly stop for several seconds then come back and above about 3500 rpm under load it's gone . unfortunately an exploratory tear down isn't in the budget right now. Any body got any ideas what would cause it?

Cold start video
https://www.youtube.com/embed/KoubmJDnyh4

GMC93

Bad lifters probably but man you really need to pull it apart to be a 100%.

Vortec350ss

iTrader: (20)

Yea a lifter could make that noise. I would change the oil and look for metal shavings in the oil. Then pull a valve cover and play with the rockers. If any of them have some play in them its a dead give away. Play with them, and then spin the motor 360 using the crank bolt and play with them again. This will make sure that even a collapsed lifter isnt just being fully compressed by a cam lobe and seemingly OK.

cadmaro

I changed the oil as soon as the noise got worse and didn't see any metal in the oil. Oil was slightly dirty and about a quart low at almost 5k miles on Mobil 1 5w30. Do these trucks have a magnetic drain plug?

cadmaro

Also, I'm not sure if it is related but the #8 coil went out around the time the noise got worse. I've also been having strange starting issues that act like a dead battery if the truck sits for more than 24hrs.

cam

iTrader: (9)

That sure sounds like its in the top end. When i pulled my 07 6.2 down for a cam swap there were four broken valve springs. Id start with popping the valve covers and rockers and check the springs as well as the push rods for true. If that doesnt turn up anything it's time to dig deeper. As mentioned there is simply no other way to know for sure until you open it up.

camcamaro1991

iTrader: (19)

I had a ticking noise since the day I took my truck home from the dealer, being a previous LS engine owner from before I figured it was normal, engine cold or warm made no difference, very noticeable next to a wall, or fast food drive through, The tech found a sloppy push rod and rocker arm on the driver side, Tech stated he replaced the push rod and rocker arm. Waiting on paper work to confirm which cylinder as the SM wrote down the wrong cylinder not even related to the same side of the engine lol. Truck as 12,000 miles.

I keep cold starting it every day and standing by it until warm to listen for the previous ticking, since the rocker arm and push rod. engine is quite as a mouse.

denaliman74

I had same noise..drove me crazy...took it to dealer last month.
problem was needed new cam,lifters,gaskets,bolts..etc
best part was that it was covered by my warranty and I had 2 weeks left on it..lmao

cadmaro

cadmaro

Turned out to be a busted piston. Replaced and Shes been running like a champ ever since