Went out to lunch and started my car and for a second or two there was a loud chatter noise. Sounded like valve chatter to me. I've had this happen a couple times randomly before after the car has sat for a few days but it's done it the last two days now and got me kinda nervous. Only did it when i started it to leave work for lunch so the car had sat for 5 or 6 hours. Didn't do it in the morning or afternoon when I started it and it had sat equally as long or longer. Have 65,000 miles on the car. Always change my oil before it gets to 50% on oil life monitor and use Mobile 1 5w30 full synthetic. Could it be the car not building enough oil pressure at start up?

 

Have a helper/friend/coworker start the engine while you listen with the hood open. If the noise is coming from the front of the engine(facing the right fender), I'd suspect that the timing chain tensioner is bad/worn.

If the noise seems to come from the center of the engine under the valve cover, you might have an oil starvation issue which is causing the cam followers to pump up slowly.

Having a tech check the oil pressurs isn't a bad idea, how many miles elapse between changes at 50% on the OLM?

 

I wish I owned some Exxon/Mobil stock.

 

Low oil level, especially when parked on a slope can lead to no oil pressure - you sure it is topped up with oil?

 

Yeah it never moves off the full mark so not a low oil level. Like I said I change the oil before it hits 50% and I do a lot of highway miles so I change the oil often. Don't know the exact mileage between changes.

 

Fwiw. If I let my SS sit for 4 or 5 days, when I start it, I sometimes get that 1-2 second valve clatter. Doesn't happen all the time. Been doing it pretty much since new.
I just think it's one of the quirks of the engine design.

I also recall a thread from way back about the serpentine belt tensioners making a similar noise. Seems the tensioner spring had a tendency to jump and make a rattle noise on startup.

 

Madmatt6988, I had a Mazda 626 a few years back that would do a valve clatter just like you are describing - would last maybe 1 or 2 secs - but would not do it every time. I lived with it, and never noticed any long-term problem.

 

Thanks for all the input.

Yeah I'm hoping it's just one of those random events that make us drivers that care about our cars nervous and treat them a little better for it. I wouldn't even have mentioned it except it did it two days in a row and had never done that. But random doesn't always mean far apart.

 

Lifter check valve may be leaking, or excessive leak down due to loose internal clearances.

 

had the same problem, doing cam swap and found like 6 valve lash adjusters stuck closed or shorter than the other ones , cleaned them with b12 chemtool and was able to fix two so far, they are like 15 each and it has 16,