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· Registered
36 Posts
Discussion Starter · #1 ·
I recently bought a 2009 toyota camry le I4 this past winter and it has 155k miles. Now that it's getting hot, i've noticed a strange knocking/loud mechanical thumping noise coming from the engine bay when I have the AC ON and put the car in Drive or Reverse. The noise occurs at any blower motor speed. The noise goes away once i start driving and rpms go over 1500. The noise doesn't occur in Park or Neutral and with the AC OFF I can put the car in drive or reverse and the noise isn't there.
At first I was thinking it could be a issue with the compressor but thought again and it could be the transmission mount since it only happens in gear.
Can someone please help give me some ideas on what this noise is from so KI can fix it please?

· Squirrel Chaser Extraordinaire
'04 Highlander, 3MZ-FE, U151E // '07 Highlander, 2GR-FSE, U151E /// '08 Highlander, 2GR-FE, U151F
323 Posts
If you have a noise similar to that mentioned, when shifting from park to drive, or from drive to reverse, do yourself a favor and check all 5 mounts (assuming a 6 cylinder engine, of course).

I chased down this sort of thing on my Highlander, ignoring all other bizarre and expensive advice (one mechanic listened to it, and very sagely told me that it was the P/S control arm), and tracked the problem down to a bad front mount (the one with the vacuum lines attached) a bad passenger-side (right-side) mount, and a sloppy dog bone on the top rear of the engine.

If you have a single or double-tap, somewhat "hollow-sounding knock" when shifting from park to drive, then into reverse, and back to drive, or even when accelerating; then have somebody cycle gears for you in the driveway while you observe the engine. You'll probably see excessive engine torque simultaneous with the knocking sound.

That pretty-much pins it down to one or more mounts.

If you see fluid leakage in the area of the the left, right, or front mounts, then replace that mount without hesitation.

· 2004 Camry LE
784 Posts
On my 2004 Camry, when I had about 50000 miles, the drain refill of ATF stopped it. Before doing something more serious I would start with this.

Good luck,
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