Thud Sound On Rear End And Silencer Leak Check

VTEC · November 30, 2010

Hi,

This is my first post hence I must say that the information available on this forum is just great and big thanks to all the contributors who are making us novices knowledgeable on cars through their experience.

Ive got a VIOS recently, which seems to be having a weird thud sound/noise coming form the rear end when the car goes over a pot hole at a speed. If its moving slow and goes over a pothole there s no sound as such.

I gave it for full service, tune up and checkup at a known service station and garage. They checked it out by driving and hoisting it up and said there seems to be no issue with anything. Took it to another garage and the baas after driving said the rear shocks needed replacement.

Replacing the shocks seems to be the logical conclusion but I just wanted some expert opinion on this.

Also the previous owner stated there was a Silencer leak and I need to fix it. The garage did not come up with issue after checking. How do I check if the there is a silencer leak or not?

Thanks in advance for your input.

jdnet · November 30, 2010

Replace the shocks. As for the silencer, Just take it into a shop that specializes in them and they will be able to figure it out. An unusually loud sounding exhaust system is a telltale sign.

SeanD · November 30, 2010

On 11/30/2010 at 7:50 AM, VTEC said:

Hi,

This is my first post hence I must say that the information available on this forum is just great and big thanks to all the contributors who are making us novices knowledgeable on cars through their experience.

Ive got a VIOS recently, which seems to be having a weird thud sound/noise coming form the rear end when the car goes over a pot hole at a speed. If its moving slow and goes over a pothole there s no sound as such.

I gave it for full service, tune up and checkup at a known service station and garage. They checked it out by driving and hoisting it up and said there seems to be no issue with anything. Took it to another garage and the baas after driving said the rear shocks needed replacement.

Replacing the shocks seems to be the logical conclusion but I just wanted some expert opinion on this.

Also the previous owner stated there was a Silencer leak and I need to fix it. The garage did not come up with issue after checking. How do I check if the there is a silencer leak or not?

Thanks in advance for your input.

The thud sound could probably be your suspension bushes failing. You can do a manual check on your suspension using your weight and your ears as well. Park the car on a flat surface and either you or a large friend can try and push down the car with your weight above each wheel. See if you can hear the thud when the car comes back up when you push down the rear. You might even be able to isolate which side this is coming from. Otherwise just have all the bushings checked and see and replace the ones that are failing.

I'm surprised that one lot would say your shocks are fine after hoisting, and the other guys would say they need to be outright replaced. Sounds like they may be trying to take you for a ride, or are trying to make some cash out of the bushing issue. Or on the flip side the guys who put it on the hoist didn't look at it properly. Of course you can change those too for peace of mind if you like. Just make sure to change the pair on the axle and not just one.

And if there's a silencer leak, it's likely you would be able to hear it (roar) . Someone with more knowledge on the subject can advice on that.

Edited November 30, 2010 by SeanD

heavyD · November 30, 2010

I believe the car bouncing up and down quite a lot when driving over potholes is a tell tale sign of a bad shock. You can check it by pushing down on each side of the car as SeanD has said. If the car bounces up and down several times, you might have a worn shock.

As for a leaky silencer; usually the car becomes louder, and the sound might be similar to a flapping noise as opposed to a (normal) smooth rumble. You know, like your car's blowing a raspberry at ya...

jdnet · November 30, 2010

On 11/30/2010 at 2:57 PM, Big_D said:

As for a leaky silencer; usually the car becomes louder, and the sound might be similar to a flapping noise as opposed to a (normal) smooth rumble. You know, like your car's blowing a raspberry at ya...

Or he could do it the stupid way like I did once. Carb cleaner in the air intake and crawled under the car to look for smoke leaking through the pipes. Accidently inhaled the smoke and almost coughed my lungs off. lol. Did find a leak that way though.

VTEC · December 1, 2010

On 11/30/2010 at 3:59 PM, jdnet said:

Or he could do it the stupid way like I did once. Carb cleaner in the air intake and crawled under the car to look for smoke leaking through the pipes. Accidently inhaled the smoke and almost coughed my lungs off. lol. Did find a leak that way though.

Thanks Jdnet, SeanD, and BigD for your input. Helps a lot. I think ill try pushing the car down and see how it responds like you guys mentioned. Ill also get the suspension bushes checked.

RE: Silencer Leak, Im not too sure about experimenting the way jdnet mentioned and filling my lungs up with smoke. Ill keep a close ear while raising it and see. There seems to be a slight noise though.

NPP · December 3, 2010

Ahhh

i got a vios too nad I posted the SAME issue long time back but didnt find anything useful..

took it to many a place, all which said the shocks are good...

bt for me it mostly happens when it falls into a pothole slowly... not so much at speed.

but i feel i have a worn out shock since the rear does not bounce wen it falls.

SeanD · December 4, 2010

On 12/3/2010 at 5:42 PM, NPP said:

Ahhh

i got a vios too nad I posted the SAME issue long time back but didnt find anything useful..

took it to many a place, all which said the shocks are good...

bt for me it mostly happens when it falls into a pothole slowly... not so much at speed.

but i feel i have a worn out shock since the rear does not bounce wen it falls.

As suggested above, check the bushings

NPP · December 6, 2010

On 12/4/2010 at 9:45 AM, SeanD said:

As suggested above, check the bushings

They removed one side of the rear shocks, checked everything and said they cant figure out what the problem was!!

heavyD · December 6, 2010

On 12/6/2010 at 2:24 PM, NPP said:

They removed one side of the rear shocks, checked everything and said they cant figure out what the problem was!!

Btw, I saw a place advertised on Hitad this week that checks your shocks. I think they have some new gadget or something. You might wanna check it out.