Engine Knock or Vacuum Pump? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Dazzo · 08-23-2021, 04:38 PM

This is a 2013 FRS Automatic, 103k miles. My engine is currently making a tapping/knocking sound, the sound is not there when the car is cold; however, when warmed up the sound is heard. My biggest fear was engine knock but after browsing other forum posts I've seen that the automatic transmissions have an issue with vacuum pumps that sounds similar. I have attached videos of the sound below, it is primarily heard on the passenger side of the vehicle. What does this sound like? Engine Knock, Vacuum Pump, or other?

humfrz · 08-23-2021, 05:19 PM

I can't tell anything from the videos.

I suggest get in closer to the vacuum pump and post a listen.

OwlDance · 08-26-2021, 04:22 AM

Sounds like some weird metallic clutter that happens either when you throttle too hard at low RPM or around the 4200 RPM mark. The deeper grunts sound like low RPM lugging to me.

08-23-2021, 04:38 PM	#1
Dazzo Junior Member Join Date: Aug 2021 Drives: 2013 FRS Location: New Orleans Posts: 5 Thanks: 0 Thanked 3 Times in 3 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Engine Knock or Vacuum Pump? This is a 2013 FRS Automatic, 103k miles. My engine is currently making a tapping/knocking sound, the sound is not there when the car is cold; however, when warmed up the sound is heard. My biggest fear was engine knock but after browsing other forum posts I've seen that the automatic transmissions have an issue with vacuum pumps that sounds similar. I have attached videos of the sound below, it is primarily heard on the passenger side of the vehicle. What does this sound like? Engine Knock, Vacuum Pump, or other?

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08-23-2021, 05:19 PM	#2
humfrz Senior Member Join Date: May 2013 Drives: 2013 FR-S, white, MT Location: Puyallup, WA Posts: 30,136 Thanks: 29,273 Thanked 32,291 Times in 16,618 Posts Mentioned: 709 Post(s) Tagged: 2 Thread(s)	I can't tell anything from the videos. I suggest get in closer to the vacuum pump and post a listen.

08-26-2021, 04:22 AM	#3
OwlDance Senior Member Join Date: Sep 2018 Drives: Halo 86, '19 Location: NY Posts: 120 Thanks: 88 Thanked 95 Times in 48 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	Sounds like some weird metallic clutter that happens either when you throttle too hard at low RPM or around the 4200 RPM mark. The deeper grunts sound like low RPM lugging to me.

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