Exhaust leak at flexible hose section of manifold (turbo)?

[insession]

Hi all,

96 850 Turbo Wagon, 228k miles.

Recently realized that the some of my motor mounts were bad. Bottom right (passenger) front one was so gone that you could pick up the entire engine by hand on that side by almost 2 inches. Ahem

Got all 5 of them replaced, great result in so many ways.

Now I have an apparent exhaust leak - but only when I start the car from cold and maybe for the first 1000 feet of driving. I can even hear it aspirating heavily during that time, and can smell some exhaust fumes in the cabin - then, the aspirating sound disappears, and so does the exhaust smell in the cabin.

Wondering if this may come from the flex hose section in the manifold, which I believe is designed for some flexibility, but surely not for the engine moving up and down by up to two inches. Ran into this possibility here:

viewtopic.php?t=25350&sid=f3628047c5f86 ... 9e81df7ad0

Any other clues what my strange symptoms could be coming from?

Thanks all,

Peter

[bmdubya1198]

The turbo engines do not have a flex pipe on the manifold, but the down pipe has a flexible section. It is not as common of a failure on them, but it can certainly happen.
It sounds to me though like your problem is with the secondary air injection, if your car is equipped with it. The air pump only runs for maybe 30-60 seconds on a cold start, and the valve on the down pipe is controlled by a solenoid. If the hose on the check valve is cracked or disconnected, that would cause an exhaust leak like you are describing.

See here for a picture of the valve’s location: viewtopic.php?t=69273

[abscate]

I think Bdub called this one perfectly. It sounds like the SAS system protocol, exactly.

[insession]

Thank you both!

Copy on the turbo not having a flex pipe on the manifold, yet, my car does not appear to have an airpump per the linked picture at viewtopic.php?t=69273 - no intake pipe, no SAS valve. See attached pic I just took of my car/engine.

The 'aspirating' sound appears to come from a low point. The flex section I was thinking of is this one: https://kyozoufs.blob.core.windows.net/ ... 454942.jpg, see also pic I just took of it in my car.

Regrettably I don't have a rack or even good jacks, so it's not so easy to be under the car when it starts.

Any other place extensive movement of the engine due to shot mounts could cause an exhaust leak - which miraculously disappears after 1000 feet or so of driving?

Peter

[bmdubya1198]

Hmm, that's strange. This seems to correlate exactly with when the SAS would run... and I think EGR was only for NAs, so you probably don't have that either.
That exhaust manifold picture is from an NA, not a turbo. The flex section you have is on the downpipe. It looks similar to that, just on the pipe rather than the manifold. You can remove the heat shield over the turbo and give it a look.

[insession]

Thanks. Sorry if I'm dense, but what's an NA? You were saying that the linked pic of the manifold isn't the same as the pic I took of the flex section in my car? Preciate your help!

[bmdubya1198]

NA = naturally aspirated (non-turbo). The picture you posted is the downpipe, not the exhaust manifold. The one on the bottom is the stock downpipe, and you can see the flexible section towards the front.
https://images.app.goo.gl/3p4jvSL4T1cCPYih6

[insession]

Ah, righto, thanks for clearing this up for me.

Still so curious what my problem could be...

[bmdubya1198]

The problems that go away after a short time are the biggest pain to diagnose. You might be able to feel around (carefully of course) when you start it up and see if you can feel a leak.

[insession]

Thanks. Have you got any experience with briefly obstructing the tail pipe (rag) to increase pressure in the exhaust system in order to find leaks more easily?