Odd noise when shifting into drive and turning AC on - Toyota 4Runner Forum

Toystory2 · 09-08-2021, 10:29 PM

I’ve noticed a noise whenever I’m idling and in drive with the brakes on like at a traffic light or drive thru. Hard to describe it, but it sounds like metal vibrating against metal coming from underneath. If I shift to neutral it will stop. Doesn’t seem to happen if I’m driving down the road either.

I also noticed that if I turn the ac on while in this situation, it causes the noise. But if I turn the ac on in neutral, there is no noise.

Not sure if it’s ac related or what. Any ideas?

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AuSeeker · 09-08-2021, 10:57 PM

Quote:

Originally Posted by Toystory2

I’ve noticed a noise whenever I’m idling and in drive with the brakes on like at a traffic light or drive thru. Hard to describe it, but it sounds like metal vibrating against metal coming from underneath. If I shift to neutral it will stop. Doesn’t seem to happen if I’m driving down the road either.

I also noticed that if I turn the ac on while in this situation, it causes the noise. But if I turn the ac on in neutral, there is no noise.

Not sure if it’s ac related or what. Any ideas?

Sent from my iPhone using Tapatalk

There are heat shields at some areas of the exhaust, many times the heat shield/s can become loose and rattle, this is more noticeable when the engine is under load, i.e. when in gear, AC is on etc., check your heat shield/s to start.

Toystory2 · 09-09-2021, 09:24 AM

Quote:

Originally Posted by AuSeeker

There are heat shields at some areas of the exhaust, many times the heat shield/s can become loose and rattle, this is more noticeable when the engine is under load, i.e. when in gear, AC is on etc., check your heat shield/s to start.

Yea that’s what it sounds like… sort of like a thin metal piece rattling. I will definitely check that out! Thank you @AuSeeker as always!

SurferUK · 09-09-2021, 09:51 AM

Quote:

Originally Posted by AuSeeker

There are heat shields at some areas of the exhaust, many times the heat shield/s can become loose and rattle, this is more noticeable when the engine is under load, i.e. when in gear, AC is on etc., check your heat shield/s to start.

A friend of mine has just eliminated some noises like OP describes from his old 2002 Toyota RAV4 - it was indeed the exhaust heat shields/clamps, and also one of the disc brake water splash guards.

It makes sense to me that it only happens in D, with the additional load on the engine, and more 'force' being transmitted throughout the driveline than when in N

Toystory2 · 09-09-2021, 01:30 PM

Quote:

Originally Posted by SurferUK

A friend of mine has just eliminated some noises like OP describes from his old 2002 Toyota RAV4 - it was indeed the exhaust heat shields/clamps, and also one of the disc brake water splash guards.

It makes sense to me that it only happens in D, with the additional load on the engine, and more 'force' being transmitted throughout the driveline than when in N

Thanks for the suggestions! I’ll check those. Been driving me crazy lol

Toystory2 · 09-13-2021, 07:00 PM

Quote:

Originally Posted by AuSeeker

There are heat shields at some areas of the exhaust, many times the heat shield/s can become loose and rattle, this is more noticeable when the engine is under load, i.e. when in gear, AC is on etc., check your heat shield/s to start.

Wonder why this seems to happen only in an idling state? I have driven slowly with the windows down and didn’t hear it.

SurferUK · 09-13-2021, 07:05 PM

Quote:

Originally Posted by Toystory2

Wonder why this seems to happen only in an idling state? I have driven slowly with the windows down and didn’t hear it.

Resonance! If it was a manual/stick shift, I bet it would rattle every time you pulled away without perfect technique. I had that exact issue on my Suzuki. No noise except when pulling away and revs dropped too low.

Toystory2 · 09-13-2021, 09:23 PM

Quote:

Originally Posted by SurferUK

Resonance! If it was a manual/stick shift, I bet it would rattle every time you pulled away without perfect technique. I had that exact issue on my Suzuki. No noise except when pulling away and revs dropped too low.

Interesting…thanks for the input. Now to find the source of this noise.

SurferUK · 09-14-2021, 06:50 AM

Quote:

Originally Posted by Toystory2

Interesting…thanks for the input. Now to find the source of this noise.

Hope it's an easy fix, let us know how you get on

Toystory2 · 10-16-2021, 06:45 PM

Quote:

Originally Posted by SurferUK

Hope it's an easy fix, let us know how you get on

Found a loose heat shield going up toward the engine. The shield has broken loose around the bolt so I was gonna put a big washer back on it, but broke the little bolt off! Now not sure what to do?

SurferUK · 10-16-2021, 06:52 PM

Quote:

Originally Posted by Toystory2

Found a loose heat shield going up toward the engine. The shield has broken loose around the bolt so I was gonna put a big washer back on it, but broke the little bolt off! Now not sure what to do?

Glad it was a minor issue. See if you can get some grips on the remaining stub, and unscrew it