Rattle @ 4k

[Tom Wilde]

Heat Shield? How can I fix it?

Tom

 

[Tom Wilde]

bump

 

[Bodge!]

bend the thing out the way!

i did mine on sunday, need to do the otherside now!

 

[Just Bob]

Possible causes are the heat shield over the CAT or the downstream oxygen sensor wiring vibrating against the heat shield.
Bend heat shield and secure wiring with a cable tie.

 

[teeCup]

ive got the 4k rattle as well! but only after ive been driving hard or for a long journey, anything to do with heat? really want to solve as its well annoying!

 

[Gus]

It could well be the mid section of the exhaust.

 

[gtruk]

see what bobRTE said. I think he is spot on the money. I get this rattle/ching ching sound at a random 3-4k rpm. Checked the o2 sensor and the wiring was vibrating up against the bottom of the gear lever arm that goes to the gearbox. SO its either that metal wiring thats hitting the heat shield, or its hitting the gear lever arm. Just get it tied up out the way

 

[mr angry]

Mine has done it for ages and its the baffles in the centre section of the exhaust.

 

[NIN-172]

If you are running the factory exhaust on a 172 ph2 then it's likely the middle section baffles that are fooked. It was a common problem a few years ago when 172s were still current.
symptoms: You get the engine warm/hot, rev it up past 4k then when you let off & the revs are dropping back down it vibrates at 4k rpm.

You can try moving heatshields & stuff, but the best bet is to get the middle section taken out & replaced with a straight through piece, which is what I had done. It doesn't make it much louder, just makes the sound a little deeper, but hardly noticable.

 

[davo172]

Baffles on exhaust centre section ! thats what it will be had mine swopped under warranty they collapse inside common 172 problem Gives you the tinny rattleing noise. Std reno dealer answer will be "OH WE HAVE NEVER HAD THIS HAPPEN BEFORE SIR"