How to diagnose if your exhaust has a leak?

[T3rminator]

As per title, what is the best way to diagnose for a leak in an exhaust, without taking it to a workshop?

When I accelerate under load there is a slight "hiss" sound. It is difficult to isolate whether its from the front or rear, left or right. At idle and free reving the sound is not evident, so its hard to pin point. The noise only comes on when I put the car under load and accelerate say from 1/2 - full throttle.

A couple of mates suggested blocking the tailpipe with wet rags and see if the leak is evident....can this damage the car?

[Jason[98.EL]]

blocking the exhaust is a good way to find a leak but i wouldnt use wet rags in the exhaust though

i would just use a hand or foot to attempt to block it off

that way if there is no leak all it will do is push your hand away from it

hope this helps

jason

[dave351cid]

Originally Posted by heljas

i would just use a hand or foot to attempt to block it off

that way if there is no leak all it will do is push your hand away from it

jason

just be carefull doing this because if it builds up pressure and blows out it can shoot you with rust and carbon schrapnell.
i still have the scars in my legs to prove it.

[dave351cid]

Originally Posted by T3rminator

As per title, what is the best way to diagnose for a leak in an exhaust, without taking it to a workshop?

When I accelerate under load there is a slight "hiss" sound. It is difficult to isolate whether its from the front or rear, left or right. At idle and free reving the sound is not evident, so its hard to pin point. The noise only comes on when I put the car under load and accelerate say from 1/2 - full throttle.

A couple of mates suggested blocking the tailpipe with wet rags and see if the leak is evident....can this damage the car?

if you climb under the car you should be able to hear if there is a leak or feel with your hands around any joints (dont touch the pipe itself if its hot :togo: ) and you will feel the air exscaping.

if its hissing when you are accelerating hard , that sounds more like a blockage like a muffler coming apart inside causing a restriction and not letting the extra gas exscape fast enough.

[Bossxr8]

Start it up and try to crawl underneath and have a listen. My old EB 5.0 had leaks in the mufflers and it sounded very choppy at idle.

[T3rminator]

So blocking the pipes temporarily won't damage the engine?

[T3rminator]

Originally Posted by Bossxr8

Start it up and try to crawl underneath and have a listen. My old EB 5.0 had leaks in the mufflers and it sounded very choppy at idle.

At idle and free reving there is no hissing sound evident. Its only when the car is in motion and I accelerate (put it under load) on half-full throttle that the hissing sound is there. Its very slight but its there.

[ebxr8240]

Originally Posted by T3rminator

So blocking the pipes temporarily won't damage the engine?

Na no way would it cause damage...
Jack car up and fit stands...
As said check, usually on bends and joins around muffler...

[naxh96]

Had this problem myself not long ago. Found it to be a broken gasket between headers and cat converter. Get a mate to hold a few rags blocking the exhaust pipe, slide yourself under a little and listen for a leak or hiss at idle. should work, as I could hear mine escaping from behind the front rear inner wheel well.

Good luck

[BlackLS]

Put a banana into your exhaust :P

[T3rminator]

Did the block test and couldn't hear or see nothing.

So jacked the car up and decided to do a visual inspection. Noticed some orange marks around a particular welding joint just after the cat. The exhaust fitter used these orange coloured sealant at the gaskets so I guessed that some of these had leaked through the hole. Anyhow, it was so small that you can't see the hole, but I was able to verify it with an auto stethescope. Amazing how such a small hole can make such an audible noise under load.