Toyota 1ZZ-FE (corolla, matrix) rattle - detailed

91l98z28

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I mounted a gopro under the hood (to an AC refrigerant line, actually) pointing at the front timing chain cover (the gold color nut is attached to the top of the serpentine belt tensioner; the camera is mounted about a foot behind the passenger headlight pointing in the general direction of the center of the firewall). Anyways, heres the video. https://www.youtube.com/watch?v=ADXb2-9r8zg You can hear the injectors kind of loudly because they are so close (the gopro is literally inches away from the engine); but you can clearly hear the sound I'm chasing at the following time points: 0:12 0:25 0:33-0:59 I intentionally move the throttle slightly around the point where it makes the noise I did also make a video of the motor at idle and revving to 3k-4k both quickly and slowly in park (not moving), but not a single sound was heard so I didn't bother to upload it. I can get a new tensioner locally and throw it in the car tomorrow and see what happens. I guess there could be some kind of resonance combined with how the crank speeds up and slows down every 180 degrees and it's causing the timing gears/cams to somehow rattle against tension/slack in the cam....I've already come this far, might as well throw one more part at it, right?
 
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I can say one thing... no one should hesitate when buying a car from you! Your cars are probably very well maintained.
 
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Sounds like piston slap to me. Not enough to cause concern. The fact that the noise is load sensitive rules out all but three things engine related: Bearing & piston clearances, and exhaust leak. The first has been ruled out. I can't see anything in the valve train being so load sensitive.
 

91l98z28

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I threw on a new timing chain tensioner for the heck of it. The old one seemed to be functional (clean, clear oil ran from it, the plunger mechanism seemed to work correctly, etc.) but it's o-ring was flattened and someone had RTV'd it at some point. I was surprised when I started it up with the new tensioner - the motor sounds a bit "smoother" (a little bit less mechanical noise in general), so that's a win (and the RTV'd o-ring was a leak waiting to happen, so that's another win); however it did nothing for the noise I'm trying to eliminate.
 
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No idea what the noise is but I used to have a 2002 Corolla that made the same noise. Kept thinking the engine was going to blow up but no, when I got done with the car my brother started driving it and it lasted 200k+. Always bugged the [censored] out of me though. I seem to recall that it didn't always make the noise (parents owned since new) but that it started at some point. My current car doesn't make any noises that are audible over the dual Magnaflows. As it should be wink
 
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Did you try soaking the pistons? Get GM Fluid 88861803 from any GM dealer and do a piston soak. What do you have to loose, 20 bucks and a hour.
 

91l98z28

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So just an update for anyone who's still interested. I spent a half hour with a stethoscope (again) today really trying to localize the sound, and while it's very hard to replicate the sound while parked, I found that having the headlights, fan, AC, etc. all on seemed to give enough load to replicate the sound for a fraction of a second when I held the rpm around 2000 and then crisply opened it slightly. Anyways, I found two rather localized spots on the cylinder head right around #4 (one on the intake side, and one on the driver side near the intake side) where the sound is notably louder. Outside the obvious (valves), there's nothing much "mechanical" there - no chain, no gears, etc., just the end of the cam and some coolant connections. Since the sound is the loudest when cold (and thus the motor is running open loop/richest), I tend to assume it's not a lean pinging/detonation issue (and thus not a poor flowing injector). I also don't think it would be a high compression issue (due to carbon or misadjusted valves) again because the cold/rich mixture would mask it (and it would get worse at operating temp, which it doesn't). That leaves me at piston slap in #4 (but why is it loudest in the head and not the block?), or some kind of unusual/atypical issue with the valves on #4. If it IS piston slap, it's definitely an annoying case. It takes almost 10 minutes to fully warm up enough for the sound to get down to it's minimum level. I read all about the LS motors and their piston slap that's gone in 30-60 seconds...this thing only STARTS getting quieter after five minutes or so. Anyways, the next "free" thing to do when I'm bored will be to pull the plugs and give them a careful one over and see if #4 looks any different, and maybe see if I can borrow one of those new cameras that are on the end of a flexible tube to take a peak down the plug holes. Might be able to use some kind of rod/dowel to see how much I can rock the piston in the bore. I might also pull the cover and take a look at the cam lobes (especially the #4 intake lobes).
 

91l98z28

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Also I did read up on the northstar cold carbon noise issues and the GM fluid. Interesting. I'll hold off on that until I can get a camera down the plug holes, but won't rule it out. As far as I'm aware, 1ZZ-FE's aren't known for this issue, but with nearly 190,000 miles..who knows.
 
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Originally Posted By: 91l98z28
Also I did read up on the northstar cold carbon noise issues and the GM fluid. Interesting. I'll hold off on that until I can get a camera down the plug holes, but won't rule it out. As far as I'm aware, 1ZZ-FE's aren't known for this issue, but with nearly 190,000 miles..who knows.
Lexus recommends it for two of their other engines. Worth a shot imo. Also a bottle of Lubegard Red might help per another poster on here. Replace pcv valve, air filter, etc.. Top tier fuel, maybe a higher octane. The 05 I have pings under light throttle. http://carspecmn.com/lexus-is250-and-gs300-top-engine-clean/
 
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Originally Posted By: kschachn
Originally Posted By: nthach
Timing chain rattle is common on these. The Corolla guys suggest replacing the tensioner before the chain and guides. It's also a common Scion/Echo/Prius malady.
So the 1NZ-FE also has the issue?
Yep. I've also been hearing Camry Hybrids with timing chain rattle as well.
 
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Originally Posted By: 91l98z28
Also I did read up on the northstar cold carbon noise issues and the GM fluid. Interesting. I'll hold off on that until I can get a camera down the plug holes, but won't rule it out. As far as I'm aware, 1ZZ-FE's aren't known for this issue, but with nearly 190,000 miles..who knows.
A piston soak wouldn't hurt - Toyota recommends the GM stuff because it's easy to get, a Chevy or Buick/GMC/Cadillac dealership is almost always near a Toyota dealer. Valvtect's Power Head Cleaner for outboard engines is the same as the old-school GM Top Engine Cleaner and the Motorcraft/Mopar relabels, just in a different spray can. Molakule here says Schaeffer's Neutra can be used as a piston soak.
 
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