1996 Avalon brief, light knocking when starting from cold
From cold start, about 10 seconds after pulling out of my driveway, under very light throttle, I get what sounds like a sticking valve banging/ clicking sound coming from what I believe is the rear bank. Almost like an overly loud spark-knocking sound. I can not duplicate it with car sitting still in neutral. The engine has to be slightly loaded, light throttle - a condition I can only replicate whilst driving. The sound goes away under heavy or no throttle, again, only when driving - engine lightly loaded. This "sweet spot" for noise is very narrow with respect to throttle position. It only lasts about 30 seconds. Once the engine warms up, I get perfect silence. I never hear the sound again during the day. Highway mileage is still 32 MPG at 170,000 miles.
I've had suggestions that it's vacuum related and that a counter-vacuum shunt needs to be added. Another - defective cam-belt tensioner. Another - exhaust manifold leak. Another - defective motor mount.
i know what you're talking about. it's a cold/dry start. most of the oil has dripped into the pan and your valvetrain isn't lubricated enough... i've heard it a couple times, but that when i haven't driven the avalon for about a week...
i know what you're talking about. it's a cold/dry start. most of the oil has dripped into the pan and your valvetrain isn't lubricated enough... i've heard it a couple times, but that when i haven't driven the avalon for about a week...
Yeah, that happened to me along time ago - when I briefly stopped using Toyota Oil filters and tried the M1 filter. After a week of being parked at the airport, it would rattle like crazy on startup. I quickly gave up on M1 filters and wrote them a nasty letter about the problem. They wrote back and said it would not void the warranty to use their filters. My car was long out of warranty and I told them I didn't give a crap about warranty - I wanted it to last well past that period and said further...that I would not be using their trash again.
This problem I now have it a bit different. And it sounds different. The symptoms are different enough that I'm sure this isn't the problem. FWIW I am coming up on an oil change and I might do it early to see if it matters....but I'm really leaning towards an exhaust leak at this time. I've got a rainy weekend ahead of me so I'm not sure I'll be able to work on it much :-(
interesting though, an exhaust leak should not disappear after 10 seconds...
or a vacuum related problem at that, those two things should be a constant if they were problems...
interesting though, an exhaust leak should not disappear after 10 seconds...
or a vacuum related problem at that, those two things should be a constant if they were problems...
keep me posted, i'm curious...
To re-clarify: It takes 10 seconds from cold start to hear it start clicking; then it takes about 30 seconds to quit.
An exhaust leak can seal with heat - which expands the metals.
Because it remains quiet all day once it gets past the first 30/40 seconds, I am prone to suspect the leak is right at the engine/exhaust manifold. Not downstream - as on the connection to the exhaust pipe.
heh. Someone told me today it might be the hydraulic lifters - sadly it does sound very much like that but - the Avalon uses solid lifters...buckets and shims..... :-(
even though the exhaust does expand as it heats, i would suspect you would still here some type of rattling as you're driving, maybe at only a specific rpm.
my heat shield rattles on my exhaust manifold in my mr2, and it only does it at a specific rpm as the exhaust manifold is vibrating at it's harmonic frequency...
The oil/filter combo might be the issue. The oil can drain back from the filter if the check valve is not working or not present. When was the last oil change? A friend just had this happen, changed the oil/filter and the problem disappeared.
The oil/filter combo might be the issue. The oil can drain back from the filter if the check valve is not working or not present. When was the last oil change? A friend just had this happen, changed the oil/filter and the problem disappeared.
Heh. I can't tell you how many times that what you are saying has gone thru my head.......but I currently only use Toyota OEM filters...and REDLINE synthetic 10W30. I am currently at 9000 miles which is about 1000 shy of when I normally change oil. I have used syn since car was new - but this last oil change was the only time I've ever tried 5W30 REDLINE. The local distributor was out of stock on my normally used 10W30. I do spin on a new filter at every 5000 miles - which is when I began to notice this clicking - now that I think back.
Dangit! Now you've really got me wondering! Thanks for making me think it thru.......
This person was using a synthetic oil (name brand-can't remember just what) that should have been within its normal life range. Sounds strange yes, but after the change the noise issues want away. Before the change sounded like very bad valve lifter chatter.
This person was using a synthetic oil (name brand-can't remember just what) that should have been within its normal life range. Sounds strange yes, but after the change the noise issues want away. Before the change sounded like very bad valve lifter chatter.
toyomoho:
You were correct! An oil and filter change reduced the noise dramatically - to the point now where I have to strain to hear it. I'll be listening carefully tomorrow morning to see if it gets totally silent - but I can live with it like it is. Thanks so much for the advice! Heh. From now on I'll be very leery of REDLINE'S 5W30 - I never had this happen with their 10W30. And there is a possibility that the Toyota OEM filter had a bad check valve - because the noise started right after I spun on a fresh filter at my normal 5K interval.
One final thought...thinking back on what all I had done to the car just prior to when the rattling started. Of course, I've already mentioned changing the oil filter just before it happened. But additionally, I just remembered that I added a bottle of Techron to the gas tank - with a bit less fuel in the tank than was recommended. Which is to say the concentration was a stronger than what was called for on the bottle.
Given that the engine has some miles on it (170,000) it's entirely possible that some raw gas blowby got into the oil and reduced it's lubricating properties or killed off its additive package............due to the high concentration of Techron.
<me scratch head>
I still however, have a nagging suspicion that a marginal check valve in the OEM oil filter would have allowed the thinner 5W30 to slip past it and drain back into the pan.
aigochamaloh and toyomoho - thanks to you both for pointing me in the right direction!
I can’t say about Techron, the stuff is a mix of naphtha, alcohol, oil and a few other chemicals. Toyota dealers flush it directly through the injection system to clean the injectors. Might be this plus the age of the oil allowed a build up of gasoline residues, etc that thinned the oil or reduced it operating characters. Or the filter check valve. Many of these valves are made of silicone, might cause problems with aging.
It Sounds Like A Discharged Lifter,or It Could Be Spark Knock Check Your Ignition Timming,keep Me Posted
I am pleased to report that after the oil and filter were changed...it took about 3 days to get back to perfect silence. The first day after was tremendously better, the second was almost there, the third day was a charm - perfect silence.
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