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What's the best way of locating an exhaust leak?

I've got blowing coming from under the car and an exhaust smell coming from under the bonnet, and suspect it could well be the rear (ES9J4) exhaust manifold gasket gone but it'll be a hell of a lot of work to get to that so I need to make sure first. I also don't want to go to all the effort only to discover it's the manifold itself or the clamp or something daft...

Any ideas how to pinpoint the leak?



PS. Want to know how much Peugeot want for a new ES9J4 cat? £1129!!!! Still £280 from eurocarparts

Im sure your familiar with the kitchen paper trick....

Can you access the clamps to the manifold from the underside easily? If so then you might not have to remove the whole thing. £280 for a CAT sounds about right. If you're fitting yourself then its a bargain (by irish standards)

eoin27 wrote:Im sure your familiar with the kitchen paper trick....

No? Wet some kitchen roll and wrap it round stuff until the sound goes or a fire starts?

Can you access the clamps to the manifold from the underside easily? If so then you might not have to remove the whole thing.

I'll probably have to drop the subframe (yet again ) to get access to anything, but getting the rear bank exhaust manifold off is a pretty involved job - removing the 2-into-1 manifold, then stripping down the throttle and inlet manifold, removing the inlet manifold (new gasket required on re-fitting), removing the exhaust manifold heat shield, then unbolting the manifold itself with very little access (4 nuts beneath, 6 on top)

mjb wrote:

eoin27 wrote:Im sure your familiar with the kitchen paper trick....

No? Wet some kitchen roll and wrap it round stuff until the sound goes or a fire starts?

Come on Matt, you must have done the old "hold a bit of tissue around a leak area to see when it moves" trick!

Did it happen all of a sudden?

Get someone* to stick their had over the end (via rag) and have a listen. Of course, depending on the seriousness of the leak the engine might stop.


*failing that a potato might do but don't have the rear of the car pointing at anything you care about...

teamster1975 wrote:Come on Matt, you must have done the old "hold a bit of tissue around a leak area to see when it moves" trick!

Nope!

Did it happen all of a sudden?

Nah, it's always been a bit smelly under there, but since driving in Ireland it's gotten embarrassingly noisy...

steve_earwig wrote:Get someone* to stick their had over the end (via rag) and have a listen. Of course, depending on the seriousness of the leak the engine might stop.

Thing is every possible source of the leak is "up there somewhere behind the engine" so I won't be able to tell unaided

You know, I might try my wet paper towel idea, except using a rag or something. That should let me rule out everything up to the manifold

With the car in the air and the undertray off, it was dead easy to find and fix it. Turned out to be one of the clamps on the front bank. Replaced it and tada!

I think it was a combination of the manifold heat shield and the undertray reflecting the sound that made it appear to be coming from the rear, but once underneath, it was dead easy to locate. The black section of pipe just confirmed it


So very glad it wasn't the rear... there's no way to get anywhere near it without taking the subframe off - the rear manifold's about 18" from the closest I can get my hand

Brilliant, well done Matt!

A nice easy fix