Engine Rattle

[Blueslover]

Hello everyone,
I have a 02 Avalon that I purchased in July that has developed a strange rattle type noise coming from the engine. Car has 95K I just had the timing belt, water pump, drive belts & tensioner replaced at 92K & changed the oil & filter with syn. oil at the same time. No noise prior to the repair, may be unrelated. Anyways, the noise is intermittent, only notice it at 1700-1800 rpm & usually at approx 40 mph. Seems to be more noticeable under slight acceleration, like going up a hill, etc. I have gotten away from ethenol gas & have run Seafoam, Bg, & other carbon/injector cleaners with each tank of gas for the last 6 tanks. Sounds like a spark knock & goes away as soon as you drop or increase the revs from that problem range. Have also noticed a slight tapping noise at idle, cold or warm from the rear vcover that sounds like a lifter or rocker. Haven't pulled the front cover to check for sludge yet. Anybody????

Thanks much!

[TrailDust]

Originally Posted by Blueslover

Hello everyone,
I have a 02 Avalon that I purchased in July that has developed a strange rattle type noise coming from the engine. Car has 95K I just had the timing belt, water pump, drive belts & tensioner replaced at 92K & changed the oil & filter with syn. oil at the same time. No noise prior to the repair, may be unrelated. Anyways, the noise is intermittent, only notice it at 1700-1800 rpm & usually at approx 40 mph. Seems to be more noticeable under slight acceleration, like going up a hill, etc. I have gotten away from ethenol gas & have run Seafoam, Bg, & other carbon/injector cleaners with each tank of gas for the last 6 tanks. Sounds like a spark knock & goes away as soon as you drop or increase the revs from that problem range. Have also noticed a slight tapping noise at idle, cold or warm from the rear vcover that sounds like a lifter or rocker. Haven't pulled the front cover to check for sludge yet. Anybody????

Thanks much!

Does the noise sound exterior or interior to the engine?

TrailDust

[Blueslover]

At idle you can lift the hood & hear something like it's in the rear valve cover. It's constant. The other noise I only hear when I'm driving, & can't tell if it's internal or not. Plus I only hear it on occassion at the 1700-1800 rpm range.

[TrailDust]

That can be a bitch to nail down when it's an RPM-related resonance. I've been there twice before, and both times it turned out to be and exhaust pipe heat shield. Definitely get as many ears on it as possible and hope you can nail it down.

TrailDust

[aaronwt]

May be its just the engine support.

[silverxls]

i've had the same problem. it is pre-ignition, or "knock". our engines have knock sensors which retard the timing when knock is detected, allowing us to run regular gas, but at that low rpm and slight throttle it can be possible the timing can't be compensated enough, that's why with just a little more throttle it goes away. it sounds like you've got everything clean so should be no problems there. i fixed it in 2 ways. first i tried premium and then plus grades of gas and both fixed it. then i changed gas stations and found that i could run thier regular without getting the knock. sometimes the cheapest gas is just that. it's worth an extra buck or so a tank to me to use better gas.