Intermittent Knocking/ Tapping Sound

[ZM1234]

Hey guys,

I have this intermittent knocking sound that seems to only be heard inside the car, specifically the drivers seat. It is kind of fast, and will come on and off occasionally. It doesn't get louder or fasting when revving, and you can only hear it really when the car is idling. When idling, you will hear it and then 10 seconds later it just stops. It is hard to identify and record due to its low volume, but it does seem to be somewhere in the dash maybe? Very stumped on this one.

Car is a 2007 Man. VE SV6, 340k km, ly7.

Sound: https://drive.google.com/file/d/12fehIQLWLYhvDJ3RXBWsdHDeUrnVEowU/view?usp=sharing

 

[Fu Manchu]

Are you sure it’s not the self test the ABS does. That sounds exactly like you describe.

 

[ZM1234]

Are you sure it’s not the self test the ABS does. That sounds exactly like you describe.

Isn't that only done when the ignition is turned on?

 

[Fu Manchu]

Isn't that only done when the ignition is turned on?

Yes.

 

[Fu Manchu]

Just because you hear that inside doesn’t mean it’s inside. Sound will refer through the body.

Like how you hear a train through the rail waaaay before you hear it normally.

I hear the shackle on the tow hitch through the cab. The chassis carries the sound through.

I’d be under that car inspecting the bushes and the engine mounts.

I’d also take a look at the centre bearing on the drive shaft. Grab the drive shaft and see how much it moves around at the centre bearing.

The other thing to check is if it’s the blower fan. I had a similar sound in a VE that was the blower fan. The motor was loose in the housing. The bearings were rooted.

You’d have to remove the blower and see if the sound is still there. Luckily it takes minutes to do.

 

[ZM1234]

Just because you hear that inside doesn’t mean it’s inside. Sound will refer through the body.

Like how you hear a train through the rail waaaay before you hear it normally.

I hear the shackle on the tow hitch through the cab. The chassis carries the sound through.

I’d be under that car inspecting the bushes and the engine mounts.

I’d also take a look at the centre bearing on the drive shaft. Grab the drive shaft and see how much it moves around at the centre bearing.

The other thing to check is if it’s the blower fan. I had a similar sound in a VE that was the blower fan. The motor was loose in the housing. The bearings were rooted.

You’d have to remove the blower and see if the sound is still there. Luckily it takes minutes to do.

managed to find a video where it is audible if you turn your volume up: https://drive.google.com/file/d/12fehIQLWLYhvDJ3RXBWsdHDeUrnVEowU/view?usp=sharing

 

[Fu Manchu]

The low tone noise?

 

[ZM1234]

The low tone noise?

The low tone is the custom exhaust. But can you hear that rapid tapping/ knocking?

 

[Lex]

The low tone is the custom exhaust. But can you hear that rapid tapping/ knocking?

No.

 

[Fu Manchu]

I’ll have another listen.