Valves loosening over time (3rz)

[Pyral]

I did my first valve adjustment in 28k miles/2 years, and since last time the valves have gotten looser. I thought they were suppose to tighten up over time.

On the exhaust side I had one gain .002 in gap, and 4 gain .001. Only 3 were unchanged.

On the intake I had 4 change anywhere between .0035-.001 (the .0005 is when the larger shim can fit in snugly), and 4 were unchanged.

Because my valves were on the tighter end on spec last time these changes put me more in spec. So no shims have to be changed. But should I be concerned that my engine is behaving the opposite of what is expected?

The only cause I can imagine is that my cam lobes are wearing away. They have a lot of varnish, but it looks identical to last time. I take good care of it.

 

[mtbtim]

Consider yourself lucky then that you didn't need to replace shims because it can be a pain in the ass. The spec can loosen from cam lobe wear and shim wear, but like you said, the spec usually tightens from valve and valve seat wear. Varnish can wear off from regular oil changes and maybe that's what you're seeing with the valve lash opening up. I'm guessing the previous owner didn't take as good of care of the engine that you do. I wouldn't worry about it. Keep driving, maintaining and enjoying your rig. You're way ahead of the game by the sheer fact you're actually regularly checking your valve lash. Happy Wrenching!

For anyone finding your thread, I figured I would post the video I made with [MENTION=148218]JZiggy[/MENTION] on this topic.

<iframe width="560" height="315" src="https://www.youtube.com/embed/f0zzsBhs3iA?si=i5NknouUvnFIBd88" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>

 

[Pyral]

Consider yourself lucky then that you didn't need to replace shims because it can be a pain in the ass. The spec can loosen from cam lobe wear and shim wear, but like you said, the spec usually tightens from valve and valve seat wear. Varnish can wear off from regular oil changes and maybe that's what you're seeing with the valve lash opening up. I'm guessing the previous owner didn't take as good of care of the engine that you do. I wouldn't worry about it. Keep driving, maintaining and enjoying your rig. You're way ahead of the game by the sheer fact you're actually regularly checking your valve lash. Happy Wrenching!

Thanks for the reply. I'm glad I don't have to change any this time, I had to change 13 or 14 of them last time.

I hoped the varnish would wear off, but it's been 3 years and it doesn't look any better. Your right about the previous owners being bad, I've seen things on this car like:
1. Oil pan gasket was replaced but they didn't clean the old RTV up before putting new gasket on
2. For some reason the front body panels weren't aligning with aftermarket side marker light, so they bent the metal body to make it fit
3. They filled in the wiring harness grommet with caulking
4. The door panel clip was broken off

 

[mtbtim]

Thanks for the reply. I'm glad I don't have to change any this time, I had to change 13 or 14 of them last time.

I hoped the varnish would wear off, but it's been 3 years and it doesn't look any better. Your right about the previous owners being bad, I've seen things on this car like:
1. Oil pan gasket was replaced but they didn't clean the old RTV up before putting new gasket on
2. For some reason the front body panels weren't aligning with aftermarket side marker light, so they bent the metal body to make it fit
3. They filled in the wiring harness grommet with caulking
4. The door panel clip was broken off

Sounds like the previous owner wasn't the brightest bulb. That's too bad, but hopefully you won't come across many more interesting repairs that were botched by him.