1Zz-Fe Engine Rattle - Corolland: the Toyota Corolla Forums

I have a 2000 Chevrolet Prizm (120k miles), which I hope is ok to post about here. It has the 1ZZ-FE corolla motor, so I think it qualifies?

I just had all the valve clearances checked today, and a couple are a little less clearance than spec, but no broken lifter springs I don't think. As the engine has a timing chain, I'm thinking maybe the rattle is due to the chain stretching considering the miles on the engine. Would a loose chain cause a rattle sound?

The symptom is very similar sounding to a BMW I had which had the exhaust camshaft slightly advanced (it was an adjustable cam engine). When I rev the engine to about what rpm you have it at as you accelerate from a light for example (the car has no tach), it rattles really bad. It does it more loudly when the engine is cold. I set the BMW's camshaft back to factory spec and it fixed the rattle completely on the BMW... this leads me to wonder if perhaps the variable valve timing is in some way not functioning correctly, rather than a loose chain.

I read in my Haynes manual that there is a little variable valve timing thing that can need cleaning, and that it also has a screen oil filter which can become dirty. Anyone know if this might cause the rattle sound?

I would hate to replace the timing chain, guides and sprockets just to discover the sound was not fixed.

Also, I already replaced the timing chain tensioner, that made no change in the sound. I also just changed the oil, so it has fresh oil and is topped off. So it's not related to low oil, at least not at this point. It could have been poorly taken care of by a previous owner, I don't know. I will upload a video later of the noise, if that helps.

Any thoughts what it could be?

Video of the rattle sound:

http://youtu.be/RGDEqeFEKKI

I found a video of someone who had the exact same sound (do you agree?), turned out it was a bad rod bearing.

Ok, I just checked the screen for the variable valve timing, it was clean.

Sounds like the common faulty belt tensioners on these 1ZZ-FE engines. Has that characteristic rattle just off idle or on deceleration. Can double check this is the case by running the car with the serpentine belt off the car and is perfectly safe to do this for a short test. Definitely will point to the tensioner being the culprit or not.

If this doesn't change the rattling - then you'll have to look at the VVT-i actuator as another possible culprit. Bad rod bearings is pretty remote - would make much more noise/get worse when you add more throttle.