Please give advice, cold start rattle...
 

2011 accord, been having the vtc cold start rattle. Had it replaced with new part r5a and no difference along with chain, tentioner and guides. What do you all do, will it do damage? Suggestions?

Accord, TSX, CRV, etc w/ the 2.4L VTEC engine suffer this problem. Despite extensive reading I have found no reports of engine damage.

FWIW, I have gone to synthetic oil and seems to have eliminated problem. However problem was very intermittent in my case.

I have not read of any definitive fixes, but also observed no reports of this problem on models earlier than ~ 09.

There is a service bulletin which describes VTC actuator replacement. https://www-odi.nhtsa.dot.gov/acms/c...41669-6712.pdf

Hard to understand why Honda can provide a definitive fix.

Maybe your rattle was something else?

good luck

I also use synthetic oil 0w 20, as called for. The reason I think it is this is it sounds identical to all the YouTube videos of this rattle. Ive read that it is related to oil draining out and not having pressure for a few sec, and that replacing the vtc oil control solenoid could fix, but I havnt found any definitive answer either.

But thanks for your thoughts. I guess the main thing is if there is no major reports of damage from this than it may not be a issue....

Low oil pressure is inevitable for a few secs.

I suspect the problem is a loose, poor fitting lock pin on the actuator. Frequently or infrequently, the pin may fail to lock on engine shutdown leaving the actuator unrestrained. When engine starts, the cam lobes slam the actuator back/forth causing the noise until oil pressure allows control of the VTC actuator. I don't know this to be the cause, and it's strictly my thought.

There are some good videos on youtube aboiut VTEC systems in general. Here's one that includes an explanation of pressure energized VTC phaser.
good luck