Gentlemen. The engine in my 2005 Rio seems to have a LOT of valve train clatter at lower RPM's. Is this endemic of those engines and should I ignore it? John--Las Vegas
The hydraulic lash adjusters could be one possibility. They make a clacking noise if the check valves inside them are leaking. There are 16 of them, so one bad one is all it takes to make noise.
Did this noise appear on its own, or only after working on the camshaft?
With the valve cover open, if you push on the hydraulic lash adjusters, they should be stiff and not compress. If any of them compress, that would be one cause for the noise.
Thanks for the info. At rpm's 1200-1500 the noisy lifter becomes nearly quiet. It its leaking down during operation, it seems to pump up a bit at speed. This was a 70K. used car I bought a month ago. I immediately changed the oil and filter. Perhaps it was a bit sludged up. We'll see. Thank you. John--LaS vEGAS
You REALLY should check the oil pressure with an analog gauge. Using the higher viscosity oil forces a higher pressure that pumps up those lifters. Rule of thumb is 10 psi for every 1k RPM. Reasons for low oil presure is bad oil pump or worn out bearings. Look carefully for "glitter" the next time you change oil.